U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

AFRL/RV Kirtland Air Force Base, New Mexico

SF.30.04.B7769: Millimeter-Wave Radio Frequency Propagation Modeling and Validation

Lane, S

(505) 846 9944

The 71-76 GHz and 81-86 GHz bands have the potential to provide ultrahigh bandwidth (gigabit per second [Gbps] data rates) point-to-point communications between a satellite and a ground station. However, one of the most crucial problems in achieving this communication link is the uncertainty of signal attenuation, phase distortion, and depolarization resulting from atmospheric absorption, scintillation, and meteorological effects (e.g., rain fade). High fidelity propagation models must be developed, statistically validated, and correlated to meteorological parameters and climatic regions as was done for the Ka-band in the 1990s to enable the Air Force to accomplish feasibility studies, systems engineering, and availability modeling to support future military satellite system architectures.

The objective of this research is to develop improved models to predict path attenuation, phase distortion, and depolarization, particularly at 71-76 GHz and 81-86 GHz. Key parameters affecting channel propagation must be identified and the functional relationship modeled.

Some of the goals of this research are (1) a model development of key communication channel properties (attenuation, phase distortion, depolarization); (2) identification of key parameters affecting channel properties (absorption, scattering, scintillation, humidity, moisture, hydrometers, rain-rate); and (3) simulations, comparison to current models

We seek applicants with backgrounds in communications theory, EM theory, or physics with understanding of radio wave propagation phenomena.

References:

Lucente M, et al: Proceedings of the IEEE: 2011

Cianca E, et al: Proceedings of the IEEE (99)11: 2011

Keywords:

Millimeter-wave; Propagation; Physics-based modeling; Communication channel properties; Atmospheric absorption; Depolarization; Scattering; Scintillation; E-band;

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B0159: Applications of Infrared Sensor Technology

LeVan, P.D.

(505) 846-9959

Opportunities exist to develop sensors based on new technology infrared (IR) focal plane arrays. The array types include those which image simultaneously in two IR wavebands, those with cut-off wavelengths approaching 14 microns with optimization for very low levels of dark current, and very large format arrays for wide fields of view with small pixel angular subtense. This research includes the identification of unique venues for economical ground- and space-based demonstrations of focal plane array technology, including the formulation of innovative concepts for fore-optics (e.g., spectroscopic, multi-waveband imaging) that exploit the latest IR focal plane array technology advancements. Related endeavors include the calculation of the signal and background photon rates corresponding to the application and to the backgrounds to which the application applies (e.g., ground-based viewing space, space-based viewing space). Emphasis is also placed on the use of commercial off-the-shelf subsystems (e.g., IR focal plane array drive and data acquisition electronics)appropriately tailored to the application, for reduced cost and risk. Finally, demonstration concepts that allow for the collection of target or background phenomenology data in support of customer requirements provide additional relevancy.

Eligibility: Open to U.S. citizens Only

SF.40.01.B5111: Data Fusion, Reasoning, Decision-Making, and Verification/Validation Approaches for Autonomous Spacecraft

Erwin, R.S.

(505) 846-9816

The ability of spacecraft to implement high-level reasoning and decision-making approaches is key to achieving several Air Force capability goals for future space systems. Benefits of on-board autonomy for spacecraft include reduced manpower requirements for mission operations, allows greater span of control for human operators and decision makers, and enables spacecraft to accomplish missions and respond to changing conditions that are un-achievable under ground-control due to communication link un-availability or latency. There are a number of technical hurdles that must be overcome before on-board algorithms will be allowed to control flight- and safety-critical functions on operational spacecraft, including analytic guarantees for the embedded control and reasoning systems used in flight software, and the ability to use systematic and rigorous verification and validation techniques that reduce the probability of undesired system behavior due to emergent behavior or implementation errors beyond what can be achieved using brute-force simulation approaches (e.g., Monte-Carlo testing). This topic seeks to develop new approaches for provably correct reasoning and decision-making algorithms (suitable for direct software implementation), the development and application of rigorous approaches for error detection and/or constraint-violating behavior of non-proven algorithms and software, as well as the application of these methodologies to spacecraft autonomy applications of interest. The project will involve cross-disciplinary research in mathematics, systems and control theory, computer science, and software engineering.

Keywords:

space; autonomy; decision; estimation; data fusion; reasoning; verification; validation; uncertainty; correctness;

References:

1. Chien, S., et. al. “Using Autonomy Flight Software to Improve Science Return on Earth Observing One,” AIAA J. Aerospace Computing, Information, and Communication, Vol. 2, pp. 196 – 216, 2005.

2. Brat, G., et. al. “Experimental Evaluation of Verification and Validation Tools on Martian Rover Software,” Formal Methods in System Design, Vol. 25, pp. 167–198, 2004.

3. Wongpiromsarn, T., Topcu, U., and Murray, R. M., “Automatic Synthesis of Robust Embedded Control Software,” AAAI Spring Symposium on Embedded Reasoning (22-24 Mar 2010, Stanford), http://www.cds.caltech.edu/~murray/preprints/wtm10-aaai.pdf (11 August 2010).

Eligibility: Open to U.S. citizens Only

SF.40.01.B5112:Control- and Game-Theoretic Approaches for Resilient Satellite Radio Communications

Pham, K.D.

(505) 846-4823

Satellite communications (SATCOM) with enhancements of radio interference mitigation, low probability of interception (LPI), and low probability of detection (LPD) can improve multi-user access, bit-error-rate performance, and throughput efficiency during congested and contested radio environments. Research opportunities exist to explore the use of control- and game-theoretic approaches to the problem of the control of the physical-layer and protocol-structures of satellite terminals and system controllers that are desired to be radio interference resistance, LPI, LPD, and low cost in anti-access and area-denial radio environments.

Specifically, related endeavors include the development of satellite system controllers and terminal modem corresponding to dynamic resource and link margin assignments to which dynamic multi-agent interactions among satellite terminals, system controllers, and adversarial actors are optimized for burst carrier frequencies, bandwidths, durations, and repetition intervals. Emphasis is also placed on the use of network topologies, consensus dynamics, game-theoretic optimization, etc. appropriately tailored to the applications of open-loop forward link time synchronization, closed-loop return link time synchronization, and wireless network time synchronization; for potential elimination of GPS and/or master-slave assistance to achieve consensus of all timing errors and global clock pulse timing in presence of adversarial spoofing and signaling. In addition, demonstration concepts that allow for radio link performance evaluation, online learning, and numerical solutions provide the support of add-on modular development of cost effective SATCOM terminal modems.

Keywords:

satellite communications, satellite terminals, system controllers, low probability of interception, low probability of detection, radio interference mitigation, dynamic resource allocation, link margin assignment, multi-agent interactions, online learning, adversarial spoofing, network synchronization, network topology, consensus dynamics, global clock pulse timing, distributed power control, game theory, add-on modular, anti-access and area-denial radio environments

References:

1. X. Tian, Z. Tian, K. Pham, E. Blasch and D. Shen, Jamming/Anti-jamming Game with a Cognitive Jammer in Space Communication, Proceedings of SPIE 8385, Sensors and Systems for Space Applications V, 2012

2. C.-G. Yang, J.-D. Li, and Z. Tian, “Optimal Power Control for Cognitive Radio Networks with Coupled Interference Constraints: A Cooperative Game-Theoretic Perspective,” IEEE Transactions on Vehicular Technology, Special Issue on Cognitive Radio, Vol. 59 (4): 1696 – 1706, 2010.

 

3. Y. Su, M. Van der Schaar, “A New Perspective on Multi-user Power Control Games in Interference Channels,” IEEE Transactions on Wireless Communications, Vol. 8 (6): 2910 – 2919, 2009

Eligibility: Open to U.S. citizens Only

SF.40.01.B5113: Advanced Spacecraft Guidance, Navigation, & Control

Erwin, R.S.

(505) 846-9816

This project seeks to develop new methods, techniques, and algorithms for challenging spacecraft guidance, navigation, and control (GNC) problems. Specifically, new approaches are being developed for (a) autonomous spacecraft relative-motion guidance and navigation approaches for rendezvous & proximity operations missions, (b) advanced attitude estimation & control algorithms for control-moment gyro, reaction wheel, and thruster-actuated spacecraft systems, (c) analysis and development of techniques for networked autonomous spacecraft performing collaborative missions such as geolocation of terrestrial search and rescue beacons or coordinated inspection of proximity spacecraft, and (d) image-based relative navigation and pose/feature extraction algorithms enabling rendezvous and proximity operations missions. Research proposals that address one or more of these topics from a theoretical or experimental point of view are of interest. This research can make use of the experimental facilities at AFRL, including a spherical air bearing attitude control and determination testbed, image-based spacecraft navigation facilities, rendezvous & proximity operations simulation capabilities, and autonomous multi-spacecraft testbeds.

Keywords:

estimation; navigation; guidance; control; spacecraft; satellites; robotics; image processing; networked control; coordinated control; autonomous systems;

References:

Baldwin, M., Erwin, R. S., and Kolmanovsky, I. V., “Robust Controller for Constrained Relative Motion Maneuvering with Disturbance Rejection,” Proc. AIAA Guid., Nav., & Contr. Conf., AIAA 2013-4721, Boston, MA, August 2013.

Hussein, I. I., Sorrentino, F., and Erwin, R. S., “Bayesian Hybrid Estimation of LTI Networked Systems using Finite Set Statistics” Proc. Amer. Contr. Conf., pp. 396 – 401, Washington, D.C., June 2013.

Weiss, A., Baldwin, M., Petersen, C., Erwin, R. S., and Kolmanovsky, I. V. “Spacecraft Constrained Maneuver Planning for Moving Debris Avoidance Using Positively Invariant Constraint Admissible Sets,” Proc. Amer. Contr. Conf., pp. 4809 – 4814, Washington, D.C., June 2013.

Luna, J. M., Abdallah, C. T., and Erwin, R. S., “Delay-dependent Stabilization of a Class of Nonlinear Time-delay Systems with Time-varying State and Input Delays,” Proc. Amer. Contr. Conf., pp. 3925 – 3931, Montreal, Canada, June 2012.

Allgeier, S. E., Erwin, R. S., and Fitz-Coy, N. G., “Velocity Extrema in Spacecraft Formation Flight,” Proc. 22nd AAS/AIAA Space Flight Mechanics Meeting, AAS 12 – 152,pp. 763 – 781,Charleston, SC, January 2012.

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B5409 : Multiscale Modeling Applied to Chalcogenide Alloys in Reconfigurable Electronics

Edwards, A.H.

(505) 853-6042

We have long recognized that chalcogenide materials such as GeTe, Sb2Te3, and As2Te3 undergo very rapid crystalline-amorphous phase transitions when subjected to either laser light or to electrical current. These materials have recently been incorporated into practical commercial products such as the re-writable DVD. There is no cogent explanation for the time scale of this transition (~tens of nanoseconds). We are also interested in the interaction of these materials with materials used in silicon technology. Our research has combined both experimental and theoretical approaches to study them. Opportunities are available to work on the simulation of the phase transitions (both directions), and on inter-diffusion and the concomitant changes in material properties using a hierarchy of techniques that includes density functional theory, classical molecular dynamics, tight-binding molecular dynamics, classical Monte Carlo, and classical continuum methods. There are also opportunities to influence the direction of our work and develop new hybrid algorithms that would couple two or more techniques. Applicants will be able to interact with a strong in-house experimental effort that includes XAFS, SIMS, SEM, TEM, Hall, Seebeck, and thermal diffusivity measurements. Local computational resources include a 46-node Beowulf cluster and access to shared DOD resources.

Eligibility: Open to U.S. citizens Only

SF.40.01.B5453: Electronic Transport in Crystalline and Amorphous Chalcogenide

Edwards, A.H.

(505) 853-6042

We have long recognized that chalcogenide materials such as GeTe, Sb2Te3, and As2Te3 undergo very rapid crystalline-amorphous phase transitions when subjected to either laser light or to electrical current. These materials have recently been incorporated into practical commercial products such as the re-writable DVD. There is no cogent explanation for the time scale of this transition (~tens of nanoseconds). We are also interested in the interaction of these materials with materials used in silicon technology. Our research has combined both experimental and theoretical approaches. Opportunities are available to perform experimental studies of electronic transport in these materials. The applicant will be expected to conduct a wide variety of experiments, including measurements of the Seebeck and Hall coefficients, and of thermal diffusivity; design and set up experiments; and collaborate with other, in-house groups working on modeling and theory of the phase transition.

Eligibility: Open to U.S. citizens Only

SF.40.01.B6640: Theoretical Studies of Optical Excitation, Quantum Transport, and Ultrafast Carrier-Scattering Dynamics

Huang, D.

(505) 846-5788

Research involves theoretical studies and numerical calculations of optical excitation, quantum transport, strong interaction of light with matters, and ultrafast dynamics of carrier scattering in low-dimensional semiconductor systems such as quantum well, quantum wire, and quantum dots. For optical excitations, the research will focus on many-body effects on absorption, photoluminescence and inelastic-scattering spectra. For quantum transports, the research will center on effects of elastic scattering, inelastic phonon scattering, and electron-electron scattering on conductances and thermo-electric powers of electrons. For strong interaction of light with matters, the research will emphasize the effects of electronic quantum interference and photonic-crystal cavity on nonlinear optics. For ultrafast dynamics of carrier scattering, the research will focus on quantum kinetics, time-resolved optical spectra, and laser damage.

Eligibility: Open to U.S. citizens Only

References:

Huang DH, et al: Physical Review B71: 195205, 2005; Huang DH, et al: Physical Review B71: 045204, 2005

SF.40.01.B6879: Advanced Structures and Materials for Space Power Generation

Wilt, D.

(505) 846 2462

On-orbit performance of power generation systems is critical to mission success. Coupled with the demands for increased power generation, it is important to develop and investigate advanced technologies capable of meeting these mission requirements. Advances in single crystal multi-junction, thin-film, and nanotechnology based photovoltaics are important to achieving improved on-orbit performance. The current state-of-the-art photovoltaic cells used for space applications are based on the III-V material systems (e.g., GaAs, GaInP). However, innovative and novel material systems and new approaches for photovoltaic materials that are capable of more effectively utilizing the solar spectrum (in terms of required mass, volume, or area per unit power generated) could provide tremendous advantages for space missions. As an example, thin-film a-Si and CIGS solar cells are being developed by multiple organizations to provide power generation for spacecraft. When thin-film solar cells are coupled with innovative solar array structures, revolutionary space power capabilities can be achieved. To effectively use thin-film solar cells in space, accurate on-orbit performance modeling is required. Accurate performance modeling of thin-film solar cells is very challenging because of poorly understood synergistic dependence on various space environmental factors (energetic protons/electrons, thermal, photons, and atomic oxygen). Since only limited synergistic ground testing is feasible, approaches must be developed that maximize ground testing results coupled with limited on-orbit data. Other forms of photovoltaic structures and materials beyond thin-film approaches are also candidates for space application and will be considered under this research topic. We expect to expand the understanding and advance solar technology through innovative research endeavors, as well as to develop an over-arching modeling strategy and to begin model development with the goal of an accurate, comprehensive, on-orbit performance model for solar cells of a variety of materials and structures.

Keywords:Photovoltaics; Materials; Space; Solar energy; Modeling; Power systems; Semiconductors;

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B7278: Advanced Estimation Concepts for Astrodynamics-Based Space Situational Awareness

Weisman, R

(505) 846-5058

This topic area focuses on Space Situational Awareness (specifically space object detection, tracking, identification, and characterization [DTIC]).

Proposed approaches in this area must deal with a number of challenges including: sensor detections that are not associated to known space objects; each space object is unique (different) and the differences in object behavior are all due to non-conservative forces and torques which depend on object characteristics (size, shape, materials, orientation).

Effective assessment of object behavior requires characterization. Moreover, sensor tasking is not optimized for data collection based upon object behavior nor data information content. Simply attempting to maximize the number of observations will not lead to successful space situational awareness.

Typically, object detection, tracking, and classification is performed in mutual exclusivity. Interdependencies amongst these are not exploited in a unified framework (e.g. Finite Set Statistics [FISST]). The proposed research must, with emphasis on inference and prediction:

1. Investigate new data/track association/correlation methods for orbit-regime-agnostic multi-sensor/multi-object DTIC for both known and newly-detected objects

2. Develop a framework to better characterize sensor level errors including biases to improve the input to the trajectory and model parameter estimation process

3. Improve nonlinear estimation and the representation of uncertainty to ensure realism in describing space object ambiguity (e.g. physically realistic/representative probability density functions)

Methods that use information theory as a framework/foundation are favored. More specifically (and what follows is of utmost importance), it is desired to receive proposals which cast the trajectory and parameter estimation process as one analogous to communication theory where the space object is considered to be transmitting a message where the message is the minimal set of states/parameters (channels), corrupted by noises and biases, that fully describe and predict observed behavior and support unique object identification and classification. Determining this basis of channels is desired as well as how to maximize the information content of those channels given available multi-sensor data, taking into account the presence of clutter and the fact that the probability of detection is often times less than unity.

References:

• Hussein, I. I., Früh, C., Erwin, R. S., and Jah, M. K. “An AEGIS-FISST Algorithm for Joint Detection, Classification and Tracking,” Proc. AAS Space Flight Mechanics Conference, Kuai, HI, February 2013 (submitted).

• Hussein, I. I., Jah, M. K., and Erwin, R. S., “An AEGIS-FISST Sensor Management Approach for Joint Detection and Tracking in SSA,” Proc. AAS Space Flight Mechanics Conference, Kauai, HI,

• Früh, C. Kelecy T. and Jah, M., (2013). Coupled Orbit-Attitude Dynamics of High Area-to-Mass Ratio (HAMR) Objects: Influence of Solar Radiation Pressure, Shadow Paths and the Visibility in Light Curves. Celestial Mechanics and Dynamical Astronomy (CELE), Accepted (8/20/2013).

• Wetterer, C., Linares, R., Crassidis, J., Kelecy, T., Ziebart, M., Jah, M., P. Cefola., (2013). Refining Space Object Radiation Pressure Modeling with Bidirectional Reflectance Distribution Functions, AIAA Journal of Guidance, Control, and Dynamics, Accepted (6/10/2013).

• Linares, R., Jah, M., Crassidis, J., Leve, F., Kelecy, T., (2012). Astrometric and Photometric Data Fusion for Inactive Space Object Feature Estimation, Journal of the International Academy of Astronautics: Acta Astronautica, Accepted (08/01/12)

• DeMars, K., Jah, M., Schumacher, P., Jr., (2012) Initial Orbit Determination Using Short-arc Angle and Angle-rate Data. IEEE Transactions on Aerospace and Electronic Systems, 48(3):2628–2637, July.

• Kelecy, T., Jah, M., DeMars, K., (2012). Application of a Multiple Hypothesis Filter to Near GEO High Area-to-Mass Ratio Space Objects State Estimation. Journal of the International Academy of Astronautics: Acta Astronautica, Accepted (07/01/12)

• DeMars, K., Bishop, R., Jah, M., (2012). An Entropy-based Approach for Uncertainty Propagation of Non-linear Dynamical Systems. AIAA Journal of Guidance, Control, and Dynamics, Accepted (11/08/12).

• DeMars, K., Jah, M., (2012). A Probabilistic Approach to Initial Orbit Determination via Gaussian Mixture Models. AIAA Journal of Guidance, Control, and Dynamics, Submitted (September).

• “Continuing Kepler’s Quest”; National Research Council (2012).

Keywords:

Data fusion; Kalman filter; Orbit determination; Attitude determination; Space object identification; Multiple hypothesis; Navigation; Guidance and control; Finite Set Statistics; multi-sensor/multi-target tracking

Eligibility:

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B7343: Space Structures

Footdale, J.N.

(505) 846-9969

Getting to and operating in space presents unique structural challenges. Structural mass efficiency, thermal response, precision, dimensional stability, packaging, and deployment all play critical roles in determining the performance of spacecraft sensor systems and addressing these needs leads to methods and architectures that are dramatically different from terrestrial systems. Work focuses on research related to structural aspects of spacecraft systems and should be traceable to improvements in systems of interest to the Department of Defense. Traditional applications include radio frequency reflectors, optical mirrors, phased array antennas, solar arrays, solar sails, and instrument booms. Structural aspects of new and emerging architecture are also highly encouraged.

*Keywords:

Space structure; Deployable structure; Space antenna; Mirror; solar array; Solar sail; Dimensional stability; Space sensor; Reflector;

*Eligibility:

Citizenship: Open to U.S. citizens only.

Level: Open to Regular and Senior applicants

SF.40.01.B7488: Satellite Guidance, Navigation, and Control Applied to Close-Proximity Missions

Lovell, T.A.

(505) 853-4132

The Air Force has a pressing need to better understand and utilize the dynamics of relative satellite motion (i.e., the motion of one satellite with respect to one or more other satellites) for close-proximity missions. These missions include both cluster/formation missions and rendezvous/proximity operations missions. The former missions typically involve multiple satellites with maneuvering capability and communication links (both with the ground and one another) performing some cooperative task (e.g., remote sensing), whereas the latter missions typically involve a lesser degree of maneuverability, connectivity, and cooperation among the satellites. Areas of relevant research include:

(1) Modeling of Relative Orbit Dynamics. The relative motion between two or more satellites in close proximity can be modeled in unique ways. The governing equations for such motion can account for a variety of physical phenomena and maybe either linear or nonlinear, time-varying, or time-invariant. We are particularly interested in the formulation of relative dynamics in such a way that it can be characterized geometrically (as opposed to using Cartesian coordinates), as well as in ways that lend themselves to the applications below. A separate area involves the analysis of natural revisit opportunities for proximity operations between satellites, using concepts such as synodic period.

(2) Relative Navigation for Satellite Systems. Satellites flying in close proximity have tight navigation requirements that may exceed the state-of-the-art in relative and autonomous navigation. These requirements include accurate estimation of both the position/velocity and attitude of the satellites. Sensing schemes include differential GPS and intersatellite ranging, using vision sensors such as radar and LIDAR. In addition to sensing, the navigation task requires accurate estimation techniques. We are particularly interested in improved filter design that may involve maximum on-board autonomy (i.e., minimum interaction from the ground), faster computation methods, use of new or unique propagation models, the ability to handle a wide variety of observation types from multiple satellites, and/or applicability over a wide range of orbital regimes.

(3) Guidance/Control Algorithms for Relative Satellite Motion. Satellites flying in close proximity have unique control requirements. Guidance algorithms must be designed taking into account both mission requirements/constraints and the natural orbital dynamics of the system. In addition, control of the satellites must often be accomplished in an optimal fashion, where trajectory time and/or fuel expenditure are of concern. The versatility of satellite cluster missions allows for reconfiguration of the satellites to perform different missions or to account for the addition or deletion of members to the cluster. Such reconfiguration will require sophisticated guidance and control algorithms. Ware particularly interested in the development of open- and/or closed-loop control algorithms for relative satellite trajectories and optimization of these trajectories. The former area may involve both centralized and decentralized control, as well as hierarchical control; while the latter area may involve both conventional (e.g., LQR, gradient-based) and modern (e.g., genetic algorithm) optimization schemes. In addition to the close-proximity maneuvering described above, we would also like to study orbit transfer techniques to achieve rendezvous, whether based on conventional methods (e.g., Lambert transfer) or lesser known methods (e.g., hodograph theory).

Keywords:

Orbital mechanics; Astrodynamics; Satellite; Guidance; Navigation; Control

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B7620: Electromagnetic (EM) Wave Radiative Transfer through Cloudy Atmospheres and Hyper-Temporal Detection of Forward/Multiply-Scattered Light

Roadcap, J.R.

(505) 853-3711

The Associate will have the opportunity to perform fundamental investigations of EM wave radiative transfer through hazy, cloudy, and precipitating atmospheres and hyper-temporal detection of forward and multiply-scattered light sources through these media. Phenomena include incident EM wave scatter, absorption, and emission by polydisperse particles with non-uniform shapes and complex permittivities, phase function, and polarized wave intensity as functions of scattering angle, molecular spectroscopic absorption, and molecular scatter. Wavelengths of interest span the ultraviolet through infrared and microwave spectral regions and can involve monochromatic or broadband sources. The novel development of hyper-temporal time series analysis methods using advanced digital signal processing and remote-sensing techniques to detect forward, multiply-scattered point source intensities will also be considered. The Associate will be expected to document, interpret, and explain their findings associated with these phenomena.

 

References

Balanis CA: Advanced Engineering Electromagnetics. New York: John Wiley & Sons, 1018: 2012

Norquist DC, Roadcap JR, et al: Journal of Applied Meteorology and Climatology 47: 1322, 2008

 

Keywords:

Electromagnetic wave; Radiative transfer; Scattering; Absorption; Emission; Polarization; Refraction; Fourier transform; Digital signal processing; Remote sensing;

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.01.B7633: Ionosphere/Magnetosphere Modeling of Wave Propagation or Wave-Particle Interaction

Su, Y-J.C.

(505) 846-7845

This opportunity encourages applicants to develop new methods or adopt existing models to study wave propagation or wave-particle interaction in the ionosphere-magnetosphere system. Research topics range from electromagnetic signals interrupted by ionospheric density irregularities (i.e., scintillation) to wave-particle interaction scattering energetic particles in the inner magnetosphere. Associates will be encouraged to develop their own research efforts making progress toward improved space weather predictions. We anticipate results from this numerical work will be directly driven by, compared to, and/or validated by ground or satellite measurements.

Keywords:

Ionosphere; Magnetosphere; Space weather; Wave propagation; Wave-particle interaction; Model

Eligibility: Open to U.S. citizens Only

13.40.01.B7961: Reactive Optimal and Robust Actuator Parameter Identification Control Allocation for Fault Tolerant Spacecraft Control

Leve, F

505.853.7476

Description: 

As a result of the unconstrained nature of space, spacecraft have the ability for unconstrained motion about all 6 degree of freedom.  For many spacecraft missions this motion must be predictable, precise, and in some instances agile.  Since spacecraft missions typically last for very long periods of time (typically on the order of 10-15 years), thanks to their high cost and long development schedules (also 10-15 years), the actuators hosted on-board spacecraft must maintain performance reliably over the same long time scale.  Some high fidelity models of spacecraft actuators do exist, but unpredictable changes resulting from faults and/or anomalies still occur because of unknown reasons (e.g., mismodeled or stochastic space environment dynamics such as radiation effects and other factors such as a change in material properties due to temperature gradients or the initial vibration profile during spacecraft launch).  Most spacecraft systems contain a substantial amount of software, actuator, and sensor redundancy to account for these changes due to faults and/or anomalies but cannot foresee or adapt for all combinations of them in the software and do not react to these changes but rather put the spacecraft in safe mode and await a solution to the problem.  Safe mode is not only a waste of mission time but also may be unsafe when changes have occurred to the spacecraft because of faults or anomalies. 

Therefore, true autonomy in guidance, navigation, and control (GN&C) is required for spacecraft missions that have complex GN&C objectives. With the recent use of code generation techniques in a slew of systems, software is produced in a more timely fashion but verification of the generated software still takes a significant portion of the assembly, integration, and testing (AI&T) of the 10-15 spacecraft development life. In addition, the software is typically only verified for foreseen faults and does not have the ability to rewrite or verify itself autonomously online when unforeseen changes resulting from faults and/or anomalies have occurred. We would like to have a GN&C system that has the ability to detect and isolate faults and/or anomalies, and react with a change to the navigation and control algorithms to optimize performance and verify that the software with the algorithm changes is safe and efficient. All of these things should be done autonomously due to the risk of uploading flight code from the ground and the amount of time the spacecraft is nonfunctional after changes have occurred.

References:

1. Robertson B, Stoneking E: Advances in the Astronautical Sciences 113: 531, 2003

2. Dennehy C: "The NASA Engineering & Safety Center (NESC) GN&C Technical

Discipline Team (TDT)": Technical Memorandum NASA/TM 2008-215128, National

Aeronautics and Space Agency, 2008

Keywords:

Spacecraft, Actuator, Control, Allocation, Fault, Anomaly, Optimal, Tolerant, Identification

Eligibility: Open to U.S. citizens Only

SF.40.01.B8159: Comprehensive Experimental and Theoretical Investigation of Electron and Hole Transport Properties through Narrow Constricted Paths with Strained, Lattice Mismatched, Semiconductor Interfaces for Ultrahigh-Frequency Optoelectronic/Electronic Device Applications

Sharma, A.K.

505.846.0165

In the nanoscale-regime, the electrons and other quasi-particles, such as holes and excitons, start to behave more like waves than particles. This transition into the quantum mechanical regime does not come about abruptly. Rather, there is a transition region in which bulk properties begin to slowly weaken while the quantum mechanical effects begin to strengthen. However, the effects of quantum confinement on carrier transport properties have been primarily investigated in ternary and quaternary material heterostructures and superlattices, in which scattering is seen to enhance some modes of electron-lattice interaction while suppressing others, thereby changing the relative value of the carrier’s effective masses of electrons and holes, as compared to bulk semiconductors. Studies of quantum confinement and transport in Si and GexSi(1-x) have been very limited. However, as Si based and GexSi(1-x) based active regions of the microelectronic devices are scaled down in all three dimensions to a few nanometers, understanding of the physics, especially electron-hole transport properties, including the role of biaxial strain, in the transition region is of great importance, particularly as it affects the overall band structure. Therefore, carrier-lattice interactions (i.e., strain effects), which includes the reversal splitting of light- and heavy-hole bands, as well as the decrease of conduction-band effective mass by reduced semiconductor bandgap energy to the extent of splitting the valence-band’s relative positions of heavy holes and light holes, as compared to bulk Si and GexSi(1-x), in turn has a direct effect on both electron and hole mobilities, thus the speed and high frequency response of the devices.

References:Ghatak BKP: Effective Electron Mass in Low-Dimensional Semiconductors. New York: Springer, 2013: 978-3-642-31247-2/0933-033X
Ohta H, Watanabe T, Ohdomari I: Japanese Journal of Applied Physics 46(5B): 3277-3282, 2007

Keywords: Semiconductor growth; Semiconductor junctions; Lattice mismatch; Interfacial strain; Nanowires; Nanoscaled devices; Nanoelectronics; Semiconductor physics; Semiconductor fabrication;

Eligibility: Open to U.S. citizens Only

SF.40.02.B0180 : Solar-Terrestrial Physics

Kahler, S.

(505) 853-3517

We conduct research on the characterization, understanding, and prediction of the key elements of space environmental disturbances. These include coronal mass ejections, high-speed solar wind streams, solar energetic particle events, and geomagnetic storms. Current research emphasizes particle acceleration and propagation from the Sun to 1 AU, solar and interplanetary sources of transient and recurrent geomagnetic storms, and periodicities (e.g., semiannual, 22 year) in geomagnetic activity. This work is based on various kinds of ground- and space-based data. We welcome proposals on interdisciplinary efforts that cross boundaries of the Sun, solar wind, and magnetosphere.

Keywords:

Solar corona; Solar wind; Solar energetic particle events; Solar storms;

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.02.B0183: Plasma Spacecraft Interactions

Cooke, D.L.

(505) 846-6150

We conduct numerous studies of spacecraft-space plasma interactions that include theory, experiment, data analysis, and computer modeling. This opportunity will emphasize computer modeling in conjunction with ongoing space and laboratory experiments. Possible research topics include critical velocity ionization phenomenon; ionization and discharge processes; optical remote sensing; neutral and ionized gas interactions with ambient medium, high-voltage systems; and natural and induced spacecraft charging. We maintain facilities for computing and scientific visualization, as well as a convenient supercomputer access.

Eligibility: Open to U.S. citizens Only

SF.40.03.B6818: Solar Physics, Space Weather. Optical Astronomy, Instrumentation

Balasubramaniam, K.S.

(505) 846-5374

Research areas include solar activity, its magnetism and evolution, and its impact on space weather using ground- and space-based measurements. We develop data driven models of eruptive solar activity, use intelligent systems to forecast solar activity, and use space situational awareness to mitigate the impact on DOD systems. Our goals are to (1) design, develop, construct, test, and deploy instrumentation for ground- and space-based measurements of solar activity using high-resolution optical imaging, spectroscopy, and spectropolarimetry; (2) develop spectroscopic radiative transfer; and (3) develop and test physics and numerical-based models of solar activity.

**References

Balasubramaniam KS, Pevtsov AA, Neidig DF: The Astrophysical Journal 658(2): 1372, 2007

Robinson BM, Balasubramaniam KS, Gilmer A: Optical Engineering 45: 3001R, 2006

**Keywords:

Space weather; Solar physics; Optics and instrumentation; Magnetohydrodynamics; Imaging; Spectroscopy; Radiative transfer; Observations; Artificial intelligence;

**Eligibility

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.04.B0205: Infrared and Visible Detectors

Huang, D.

505-846-5788

We perform theoretical and experimental research on infrared detectors made of HgCdTe, and superlattice (SL) IR detectors made of II-VI and III-V material systems, such as HgTe/CdTe and InAs/InGaSb. We investigate the band structure, absorption coefficient, quantum efficiency, dark current etc of these materials and detectors.We are currently studying the following topics: p-type doping in HgCdTe, alternate substrates for HgCdTe and SL detectors, methods to decrease dark current and increase uniformity, increase operating temperature etc. There is also interest in Si hybrid visible detectors. Available laboratory equipment include Fourier-transform IR spectroscopy, and all the equipment necessary to fully characterize detector performance from room temperature to cryogenic temperatures. We collaborate with the University of Illinois, North Western University, and Army Research Laboratory.

References:

Yong Chang, Christoph H. Grein, Sivalingam Sivananthan, M.E. Flatte, V. Nathan, and S. Guha, "Narrow Gap HgCdTe Absorption behavior near the Band Edge including Nonparabolicity and the Urbach Tail," Appl. Phys. Lett. 89, 062109 (2006);

Binh-Minh Nguyen, Darin Hoffman, Pierre-Yves Delaunay, Manijeh Razeghi, and Vaidya Nathan, "Polarity inversion of type II InAs/GaSb superlattice photodiodes," App. Phys. Lett. 91, 103503(2007);

Andrew Hood, Pierre-Yves Delaunay, Darin Hoffman, Binh-Minh Nguyen, Yajun Wei, Manijeh Razeghi and Vaidya Nathan, "Near bulk-limited R0A of long-wavelength infrared type-II InAs/GaSb superlattice photodiodes with polyimide surface passivation," Appl. Phys. Lett. 90, 233513 (2007).

Eligibility: Open to U.S. citizens Only

SF.40.04.B0205: Electron Dynamics and Performance Issues in Infrared and Visible Detectors

Huang, D.

505.846.5788

We perform both theoretical and experimental researches on III-V and II-VI semiconductor-based quantum-well (QW) and superlattice (SL) infrared (IR) detectors, such as HgTe/CdTe, InAs/InGaSb, and GaAs/AlGaAs QWs and SLs. We investigate the band structure, optical absorption, quantum efficiency, dark, and photo-current of these materials and detectors, as well as new designs of surface-plasmon enhanced, frequency tunable and polarization-sensitive IR detectors. We are also interested in silicon visible detector arrays hybridized with CMOS readout circuits. Available laboratory equipment includes Fourier-transform infrared spectroscopy, time-resolved photo-luminescence spectroscopy for carrier lifetime measurement, and all the equipment necessary to fully characterize detector performance from room temperature to cryogenic temperatures. Very recently, we are expanding our research interest to theoretical and experimental studies on proton radiation degradation of electronic and optoelectronic devices.

References
Huang DH, et al: Optics Express 22: 27576, 2014
Cardimona DA, et al: Infrared Physics and Technology 54: 283, 2011
Chang CC, et al: Nano Letters 10: 1704, 2010
Huang DH, et al: Transactions of Nanotechnology 7: 151-164, 2008
Kossyrev PA, et al: Nano Letters 5: 1978, 2005

Keywords: Infrared detectors; Quantum wells; Superlattices; Proton radiation degradation; Frequency-tunable detector; Polarization-sensitive detector; Surface-plasmon enhancement;

Eligibility: Open to U.S. citizens Only

SF.40.04.B0207: Research and Development in Passive Sensors

Cardimona, D.A.

(505) 846-5807

Research opportunities in the Advanced Detectors Research Group of the Space Vehicles Directorate are extremely varied. Experimental and theoretical research focuses on new detector development in the ultraviolet to mm-wave wavelength range (currently specializing in infrared [IR] and longer); new detector capabilities such as wavelength tunability and polarization discrimination; and detector interactions with external electric, magnetic, and electromagnetic fields. We are currently concentrating on III-V semiconductor multiple quantum well, superlattice, quantum wire, and quantum dot heterostructures. We have begun investigating the possibilities of organic polymers and nanotubes for IR detection. Our main emphasis is on space-based applications of these new detector designs, so we will always be concerned with radiation hardness and high sensitivity in our studies. We mainly investigate single detector pixels, but we are also interested in full focal plane arrays. Our current research interests include (1) optical-spectroscopy studies such as absorption, photoluminescence, light scattering, and ultra-fast pump/probe transient spectra; and (2) quantum-transport studies such as tunneling, drift, diffusion, and field domains. Available characterization equipment include Fourier-transform IR spectroscopy, magneto-transport and magneto-optical, deep level transient spectroscopy, femtosecond laser pump/probe, and all the equipment necessary to fully characterize detector dynamics and performance at cryogenic temperatures. We have extensive collaborations with universities around the country, especially the University of New Mexico, where we can obtain access to MBE machines, clean rooms, SEMs, and AFMs.

Eligibility: Open to U.S. citizens Only

SF.40.04.B8143: Nonlinear Plasma Processes in the Subauroral Geospace Weather

Mishin, E.V.

505.846.7227

The subauroral ionosphere lays just equatorward of the auroral boundary. It maps along magnetic field lines into the inner magnetosphere, which includes the ring current (RC), innermost part of the outer radiation belt (RB), and plasmasphere adjacent to the electron plasma sheet (PS) boundary. For brevity, we call this ionosphere-magnetosphere region the subauroral geospace. The quiet time convection in the subauroral geospace is virtually featureless. During (sub)storms, latitudinally narrow jets of subauroral westward convection, subauroral ion drifts (SAID), emerge in the pre-midnight sector, while broad westward flows, subauroral polarization streams (SAPS), appear in the duskside. Just after the substorm onset, SAPS are highly structured and termed SAPSWS (wave structures). SAPSWS co-locate with RB and RC particle precipitation, radar clutter, and UHF/GPS scintillations. Though the development of SAID/SAPS and related space weather effects have been under investigation for decades, the understanding of the underlying physics, especially rapidly developing intense features near substorm onsets, is still lacking.

It is generally implied that poleward electric fields Es driving SAID and SAPS develop due to similar, if not the same, mechanisms, known as voltage and current generators. The former places SAID/SAPS between the inner boundaries of ≥1-keV ion and electron convection defined by the E×B and gradient-curvature drifts. The latter explores closure of the Region 2 field-aligned currents (FACs) through a low-conductive ionosphere, resulting in locally enhanced poleward electric field. The generator concept is based on the test (single) particle approach and has come to be called the SAID/SAPS paradigm. However, recent studies show that the paradigm is in serious error. One of the most striking discrepancies is that the paradigm predicts the timescale of a few hours, while substorm subauroral events appear in ~10 min or less.

The fast timescale and SAID’s MLT sector are characteristic of the propagation of substorm injections (hot plasma jets). Therefore, we develop a concept of the SAID channel as an integral part of a turbulent plasmaspheric boundary layer (TPBL). TPBL forms in the evening sector where the plasmasphere short-circuits reconnection-injected plasma jets. However, we still know little about the underlying mechanism of SAPS, particularly SAPS wave structures (SAPSWS), except that nonlinear plasma effects are critical. Transient SAPS enhancements also appear at times well separated from substorm onsets and correlate with auroral streamers, the footprint of mesoscale plasma jets in the magnetotail. These observations hint at a common process underlying the SAPS/SAPSWS generation and the over-arching problem of transport of reconnection-created jets toward the Earth. The required level of understanding of basic plasma processes that control the spatiotemporal development of the perturbed subauroral geospace can only be achieved using a multidisciplinary effort utilizing experimental, theoretical, and numerical investigations.

Reference: Basu S, et al: Journal of Geophysical Research 113: A00A06, doi:10.1029/2008JA013076, 2008
Makarevich R, et al: A. Kellerman, Journal of Geophysical Research 116: A11311, 2011
Mishin E, Puhl-Quinn P, Santolik O: Geophysical Research Letters 37: L07106, doi:10.1029/2010GL042929, 2010
Mishin E, Albert J, Santolik O: Geophysical Research Letters 38: L21101, doi:10.1029/2011GL049613, 2011
Mishin E: Journal of Geophysical Research 118: 5782, doi:10.1002/jgra.50548, 2013

Keywords: Space weather; Subauroral geospace; SAPS/SAID; Plasmaspheric boundary layer; Substorm injection; Ring current injection; Radiation belt boundary;

Eligibility: Open to U.S. citizens Only

SF.40.06.B0170: Plasma Chemistry for Space Applications

Viggiano, A.A.

(505) 853-3399

We study a broad range of plasma chemistry including electron attachment, ion-molecule reactions, dissociative recombination, and mutual neutralization. We specialize in studying difficult species, radicals, and extended temperature ranges. Several fast flow plasma reaction apparatuses are used. The ion-molecule temperature range is 90-1800 K, while for the other plasma processes temperatures up to 1400 K can be studied. Recent successes include measuring the only product distributions for mutual neutralization, electron attachment to fluorocarbon radicals, and the discovery that electrons catalyze mutual neutralization. A recent upgrade has allowed for studies of radicals with electrosprayed ions, which is important for solar fuels research.

The data support a wide variety of AF/DoD applications including the natural ionosphere, hypersonic vehicles, plasmas assisted combustion, high power lasers, conversion of gaseous to liquid fuels, trace gas detection, high energy density materials, and other catalytic processes.

Eligibility: Open to U.S. citizens Only

SF.40.07.B0179: Advanced Space-Based Imaging

Lipson, S.J.

(505) 853-3531

We develop and exploit multiple technologies for space-based optical and infrared detection and identification, with an emphasis on advanced imaging sensor payloads. Possible research topics include imagery data analysis, object identification algorithms, signal processing, satellite on-board processing, data compression, time-series analysis, sensor calibration, modeling of atmospheric transmission and compensation, and other topics related to space-based remote sensing, object identification, and payload design. We have facilities for algorithm development, modeling and simulation, and an in-house sensor calibration facility.

Eligibility: Open to U.S. citizens Only

SF.40.07.B5812: Optical Sensing of Ionospheric and Upper Atmospheric Structure and Dynamics

Pedersen, T.R.

(505) 853-3792

Detection of optical emissions from the upper atmosphere is one of the few means of determining ionospheric and upper atmospheric structure and conditions over large regions. We seek to find improved ways to utilize optical emissions as a diagnostic for conditions in the natural and modified ionosphere. Efforts include development of image processing algorithms, optical filtering techniques, instruments and detectors, and techniques for assimilation of optical data into models. Techniques for automated recognition, detection, and tracking of disturbances such as polar cap patches, auroral arcs, or equatorial depletions will improve specification and forecast of ionospheric conditions and effects on systems. Accurate determination of motion, reaction rates, species densities, or energy or current fluxes can provide input and constraints over large regions for assimilative or theoretical models otherwise dependent on small numbers of measurement points. Interest areas include the natural ionosphere at high, middle, and low latitudes, and artificial effects induced by chemical releases, spacecraft maneuvers, particle beams, or radio waves. Data sets may include measurements from either or both ground- and space-based systems, operating at night, or during daylight. We are also interested in data quality control strategies including cloud detection and background light removal, as well as advanced techniques such as tomography or multispectral imaging. Our group maintains a large data base of optical images from locations around the world as well as a large suite of low-light imaging equipment, and also participates in ionospheric modification experiments.

Reference

Ashrafi, M, M. J. Kosch, and F. Honary, Comparison of the characteristic energy of precipitating electrons derived from ground-based and DMSP satellite data, Annales Geophysicae, 23, 135-145SRef-ID: 1432-0576/ag/2005-23-135, 2005; Gustavsson, B.; Sergienko, T.; Kosch, M. J.; Rietveld, M. T.; Br ndstr m, B. U. E.; Leyser, T. B.; Isham, B.; Gallop, P.; Aso, T.; Ejiri, M.; Grydeland, T.; Steen, .; Lahoz, C.; Kaila, K.; Jussila, J.; Holma, H., The electron energy distribution during HF pumping, a picture painted with all colors, Annales Geophysicae, Volume 23, Issue 5, 2005, pp.1747-1754, 2005; Martinis,C., J.V. Eccles,J. Baumgardner,J. Manzano,and M. Mendillo, Latitude dependence of zonal plasma drifts obtained from dual-site airglow observations, Journal of Geophysical Research (Space Physics), Volume 108, Issue A3, pp. SIA 8-1, CiteID 1129, DOI 10.1029/2002JA009462, 2003

Eligibility: Open to U.S. citizens Only

SF.40.07.B5822: Seismic and Infrasound Research for Monitoring Nuclear Explosions

Xie, J.

(505) 846-6051

Underground nuclear explosions generate seismic and infrasound waves. Monitoring underground explosions encompasses a wide range of seismic and acoustic disciplines. The source mechanics must be understood in terms of the amount and type of seismic and infrasound radiation produced-not only by underground nuclear explosions, but also by other sources such as small shallow earthquakes and industrial explosions. The effects of propagation (including attenuation) through the solid Earth or atmospheric medium control the travel time, amplitude, and other characteristics of waves measured at a seismometer or microbarograph. These basic problems control the ability to perform the practical procedures of detection and location of an event, identification of the event as a nuclear explosion or some other type of source, and estimation of the yield if it is an explosion. Methods of tackling the research problem include theoretical investigation of source physics, modeling and simulation of seismograms and microbarograms to better understand both source and propagation processes, and observational studies of seismic and acoustic wave characteristics and Earth/atmosphere models. We are particularly interested in studies of relatively small (magnitude <4) shallow seismic sources and propagation at local (<200 km) and regional (<3,000 km) distances.

 

Keywords:

Seismic; Seismic sources; Seismic wave propagation; Infrasound; Infrasound sources; Infrasound propagation; Underground nuclear explosions; Nuclear explosion monitoring; Earth models

Eligibility: Open to U.S. citizens Only

SFFP.40.09.B7485: Laser Spectroscopy of Next-Generation Propellants

Stearns, Jaime A

505 846 6998

Our research centers on the chemistry of space vehicles: the reactions involved in hypergolic ignition and the subsequent interactions between the thruster plume and the near-space environment. We are currently interested in the spectroscopy, structure, and reactivity of novel ionic liquid propellants, which are being pursued as a next-generation, “green” alternative to the toxic hydrazine-based systems currently in use. Ultraviolet spectroscopy of gas-phase ionic liquid ion pairs in a supersonic jet provides optical signatures of these new compounds. Infrared spectroscopy identifies distinctive molecular vibrations, which are compared to vibrational frequencies calculated using standard computational chemistry methods. This comparison allows us to determine the ion pair structures present in the experiment, as well as to rigorously test the methods of theory employed. We are also developing an instrument which will use electrospray to transfer clusters of ionic liquids into the gas phase, where they will be stored in a cold ion trap for studies of their spectroscopy and hypergolic reactions.

Keywords: Lasers; Spectroscopy; Mass spectrometry; Propulsion; Computational chemistry; Spacecraft;

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.10.B8178: Embedded Systems Cyber Resiliency

Naudeau, M.L.

505.853.7107

The United States Department of Defense (DOD) continually designs, acquires, and deploys best in class, highly complex and capable embedded systems. Due to their often high cost, low density, long development timelines, and the mission criticality of the services they may provide, DOD embedded systems present highly attractive targets to our adversaries. As we have embraced enhanced embedded system capabilities, in some aspects we have become increasingly vulnerable to certain types of cyber-attack. Across the wide array of adversary capabilities that may be employed against a modern embedded system, cyber-attack is often the most poorly understood, the hardest to quantify, has few to often no observable symptoms, indications, or warnings, and in some cases has the lowest cost to entry. For these and other reasons, cyber-attack has become a growing but misunderstood area of concern for the DOD. Meanwhile, Stuxnet and other custom cyber exploits have demonstrated to the embedded systems community that nations can, have, and will continue to use cyber techniques to achieve their national security objectives, to include delivering combat effects against the highest value embedded systems.

This is a broad research topic to explore technologies intended to enhance the mission assurance properties of embedded system architectures in cyber-contested environments. Specific topic areas of interest include but are not limited to (1) researching cyber vulnerability metrics and developing formal tools and techniques for evaluating architectural, specification, and implementation weaknesses and vulnerabilities in embedded system components and architectures; (2) developing application and risk-level tailorable sets of embedded system cyber-security design guides/requirements; (3) researching and developing techniques and methods to analyze cyber-behavioral observables within an embedded computing system in order to identify indications and warnings of an advanced persistent threat, intrusion, or other anomalous cyber behavior; and (4) other active defense and root of trust techniques, including developing binary/runtime assurance toolsets, boottime and runtime verification modules, and whitelisting, access control, and trust scoring/figure of merit techniques.

Keywords: Cyber; Software assurance; Embedded system cyber security; Cyber resiliency; Root of trust; Cyber vulnerability mitigation; Runtime security; Active cyber defense; Software engineering;

Eligibility: Open to U.S. citizens Only

SF.40.12.B8174: Passive Optical Remote Sensing and Imaging of Manmade Objects in Geosynchronous Earth Orbit

Crabtree, P.N.

505.846.0437

Our research centers on techniques for passive optical remote sensing and imaging of manmade objects in geosynchronous Earth orbit (GEO). Resolved imaging of GEO satellites continues to be a challenging problem due their great distance from both ground-based locations and low Earth orbit (LEO). We are currently interested in (1) both data processing techniques and optical designs to maximize the imaging performance of space-borne cameras and (2) more exotic synthetic aperture techniques, such as shadow imaging based on measurements of the Fresnel diffraction pattern of the object silhouette during stellar occultation. Interferometry techniques are also of interest, but since they face immense technical and engineering challenges, the simpler measurement process of shadow imaging is currently of greater interest. Image processing codes and techniques developed may be applied to data captured by AFRL space experiments. Synthetic aperture techniques are studied by analysis and simulation; results will guide future imaging architectures and experiments aimed at improved characterization of space objects.

Keywords: Remote sensing; Synthetic aperture; Shadow imaging; Multiframe image enhancement; Image registration; Optical flow; Stellar occultation; Super-resolution; High dynamic range;

Eligibility: Open to U.S. citizens Only

SF.40.12.B8192: SSA Characterization

Milster, S.P.

505.846.7752

We seek an Associate for a position in Space Situational Awareness (SSA) Characterization. The work will involve merging photometric (visible and near IR) observations with novel approaches at detector and orbital dynamics characterizations. Experience has shown that the photometric state of a Resident Space Object (RSO) is directly related to its physical state. Advances in SSA characterization will likely come from pushing the algorithms that measure raw data, extract orbital motion information, and extract information about the photometric state. The successful candidate would have expertise and/or interests in observational photometry, calibrations, faint object detection, orbital mechanics, and algorithm development.

References
Ferguson DC, et al: Journal of Spacecraft and Rockets 51(6): 1907-1913, 2014
Skinner M, et al: Commercial Space Situational Awareness–An investigation of ground-based SSA concepts to support commercial GEO satellite operators, in Advanced Maui Optical and Space Surveillance Technologies Conference (Volume 1, page 9) September 2013
Skinner MA, et al: Acta Astronautica 105(1): 1-10, 2014

Keywords: SSA; Space; Situational awareness; Photometry; Characterization; Satellite; Visible; near IR;

Eligibility: Open to U.S. citizens Only

SF.40.14.B1112: Game-Theoretic Based Decision Support Tools for Persistent Space Threat Interdiction

Pham, K.

(505) 846-4823

Today the US has a tremendous investment in space, especially in military, intelligence, scientific, and commercial sectors. However, one of the most important space vulnerabilities is the lack of persistent situation awareness of the space operational environment to ensure freedom of action. Space can be an important battlefield in modern warfare because intelligence information from space has become extremely vital for strategic decisions. In addition to real-time and hidden information constraints, the presence of adversaries greatly complicates the decision making process. It becomes necessary to perform space defense analysis and mission trade studies. Although pursuit-evasion game theory is relevant to this problem, most results in the existing literature are from the pursuers’ perspective and not applicable. Innovative solutions are sought for (1) proper game models and constructive game training for a generic space defending scenario where multiple denying assets, defending assets, and pursuing assets with either equal or unequal capabilities are assumed with imperfect, sporadic observations and jamming confrontations; (2) possible constructive methods and approximate solution techniques on distributed learning under sparse communications and adverse environments; (3) efficient computational algorithms to determine real-time cooperative strategies for the space assets, neutral objects, and threats in persistent area denial; and (4) assess the performance under technical failure inaccurate measurements and loss of communications. Proposed advances--together with potential deliverables including novel mathematical developments, interaction modeling, performance metrics, advanced engagement concepts, and design principles--set the foundations to enable assured operations of teams of autonomous defense systems to adapt to hostile, nontraditional environments, which capitalize on effective utilization of modeling and analysis of uncertain systems, as well as multilevel, multi group, multi-agent, control and decision analysis.

References:

Shen D, Pham KD, et al: “Pursuit Evasion Orbital Game for Satellite Interception and Collision Avoidance,” SPIE Defense and Security 2011: Sensors and Systems for Space Applications IV, Proceedings of SPIE 8044: Orlando, FL, 2011

Pham KD: “Risk-Averse Based Paradigms for Uncertainty Forecast and Management in Differential Games of Persistent Disruptions and Denials,” Proceedings of American Control Conference: 842, Baltimore, MD, 2010

Keywords:

Active and distributed learning; Modeling of complex systems; Competitive decision making; Adversarial systems; Distributed computation; Multilevel command and control in hostile environment

Eligibility: Open to U.S. citizens Only

SF.40.14.B1115: Blind and Beacon-Less TDMA Scheduling for Ad-Hoc LEO Satellite Communications

Pham, K.

(505) 846-4823

Future satellite missions require radio frequency (RF) subsystem architectures with low size, weight, and power (SWAP) that can support remotely piloted aircraft (RPA)’s high data rates at the order of Gbps for both uplinks and downlinks. To meet the ever increasing demands of high data rates, the most commonly used technology in RPA communications is often to be dual polarization in conjunction with time division multiple access (TDMA) and a constellation of Low-Earth-Orbiting (LEO) satellites. Currently, the TDMA technique for LEO satellites requires satellite radio beacons (or pilot tones) to perform TDMA scheduling. Any satellite payloads, which require space radio beacon systems, will increase the SWAP requirements. In this opportunity the Air Force is soliciting innovative R&D advances to enable future technology capabilities in the following aspects: (1) revolutionary design principles using TDMA scheduling without space or satellite radio beacons, (2) robust analysis on satellite fingerprints to search for satellite identification and availability, (3) on/off-board TDMA scheduling to efficiently disseminate schedules to RPA platforms, and (4) TDMA scheduling techniques with and without requiring a priori knowledge of satellite locations. The introduction of this emerging capability onto satellite platforms should have minimal impacts on SWAP requirements and require no a-priori knowledge of satellite locations.

References:

Nguyen TM: Plenary Paper, SPIE Defense and Security 2013: Sensors and Systems for Space Applications VI, Proceedings of SPIE, Vol. 8385: Baltimore, MD, 2013

Kwan WC, Sieteng S, Chen M: A Novel Spatial TDMA Scheduler for Concurrent Transmit/Receive Wireless Mesh Networks, 24th IEEE International Conference on Advanced Information Networking and Applications: 2010

Keywords:

Satellite radio beacons; Feature extraction and inference; Satellite fingerprints; Spoofing and jamming; TDMA scheduling; Sparse observations; SWAP

Eligibility: Open to U.S. citizens Only

SF.40.14.B1116:Resilient System Controllers and Terminals for Wideband Global SATCOM

Pham, K.

(505) 846-4823

The satellite communications industry expects the US reliance on beyond-line-of-sight, in-transit communications, and a range of communications from narrow to broadband to drive an ever-increasing demand for secure and resilient communications that will render the current Wideband Global SATCOM (WGS) systems unable to full fill this unprecedented quest. To respond to this new demand, new add-on modular capability concepts are being sought for future development of resilient system controllers, airborne and/or ground terminals via WGS satellite transponders, which will therefore provide jamming resistance, low probability of interception, low probability of detection, etc.

In particular, modeling, simulation and analysis associated with system controllers, airborne and/or ground terminals include (but not are limited to): (i) wideband spectrum surveillance that can responsively interconnect multiple spectrum monitoring units together for spectrum comparison either at radio or intermediate frequencies and thus, automatically assess whether any interference being experienced is being caused on the satellite uplinks or downlinks; (ii) dynamic resource allocation (DRA) enabled by competitive decision-making frameworks for radio resource and link margin assignments that can best respond for airborne and/or ground terminals in presence of radio interferences and in accordance of channel state information; and (iii) forward and return link multiple accesses supported by universal modulation and demodulation techniques together with frequency-time burst approaches to transport existing WGS waveforms through contested environments. Promising outcomes as mentioned in (i) through (iii) should include signal processing for spectrum monitoring, DRA decision processing for satellite system controllers, integration considerations describing commercial satellite antenna and signal re-uses as well as open control interface assessments with minimal impacts on commercial satellite hubs and terminals.

References:

1. M. Glaser, K. Greiner, et. al., “Protected MILSATCOM Design for Affordability Risk Reduction (DFARR),” IEEE MILCOM Conference, 2013

2. E. Hall, et. al., “Fractionated, Cognitive Approach to Anti-Jam SATCOM Using Commercial Satellites”, IEEE MILCOM Conference, 2012

3. K. L. B. Cook, “Current wideband MILSATCOM Infrastructure and the Future of Bandwidth Availability,” IEEE Aerospace and Electronics Systems Magazine, pp. 23-28, 2008

Keywords:

 

WGS SATCOM, dynamic resource allocation, system controllers, airborne and/or ground terminals, add-on modules, low probability of interception, low probability of detection, radio interferences, spectrum monitoring, DRA decision processing, link margin assignment, forward and return multiple access, frequency-time burst, WGS waveforms, antenna and signal sharing, open interfaces.

Eligibility: Open to U.S. citizens Only

SF.40.12.B7987: Cold-Atom Precision Timing and Inhertial Navigation

Olson, S.

(505) 846-4799

The subject of our research is precision timing and inertial sensing enabled by laser-cooling, trapping, and advances in photonics. One of our major efforts pursues the development of robust, miniaturized optical clocks and associated frequency combs in order to develop a cost-effective replacement for the atomic clocks aboard the global positioning satellite constellation. Another major effort uses atom-chip devices to develop confined atom interferometry. Confined interferometry offers the possibility to dramatically increase interrogation time of atom-based inertial sensing devices. We use a rapid prototyping technique for atom chips that allows us to quickly customize and live-test atom chip structures. We are also exploring techniques for developing compact atomic-devices, including large-diameter hollow-core fiber guiding and integrated atom-chip transport. More recently, we have begun investigating the development of atom-chip-based continuously replenished (CR) Bose-Einstein condensate (BEC). A CR BEC will be the leading steps into achieving a truly continuous-wave atom laser.

Keywords:

Quantum enhanced scattering; Atomic clock; Ultracold atoms; Bose-Einstein condensate; Frequency comb; Atom laser; Hollow-core fiber atom guiding; Atom chips; Atom interferometry

Eligibility: Open to U.S. citizens Only

Level:  Open to Regular and Senior applicants

SF.40.12.B8020: Development of Methods for Local and Near Regional Seismic Event Discrimination and Characterization

Baker, G.

(505) 846-6070

There is a need for improved methods for discriminating nuclear explosions from earthquakes and other natural and man-made seismic sources, and characterizing suspicious seismic sources. The technical challenges are driven by the need to monitor smaller events.  Recordings of smaller events are generally sparser, made at closer distances (local and near regional), have lower signal-to-noise ratios, and have maximum signal amplitudes at higher frequencies than recordings of larger events. These differences all present challenges. Of the two most effective discriminants, phase ratio discriminants can fail at local distances and in areas with high attenuation, while the Ms:mb discriminant may not work for small shallow events (Stevens and Day, 1985). In addition, monitoring requirements evolve in response to geopolitical events, which drives a need to monitor in new regions that are often poorly calibrated both empirically and with respect to the resolution of available Earth models. The need to use higher frequency and lower signal-to-noise ratio waveforms for smaller events exacerbates the problems that arise from insufficient Earth model resolution. This drives a need for discriminants that are robust to high attenuation and limited means for removing propagation effects from seismic waveforms.

These requirements drive a need for extensions of existing discriminants to make them more effective for the challenging monitoring conditions described above, and for new discriminants that are effective for small events recorded sparsely at local and near regional distances. New methods will require a firm physical basis to support their application in new areas.  Inversion for regional moment tensors is currently an effective automated means (e.g. Ekström et al., 2012) of identifying earthquake focal mechanisms and for separating populations of different events types (Ford et al., 2009) at regional distances. Statistically rigorous uncertainty estimates however are needed, as are methods to improve resolution for smaller events, for which propagation effects are more difficult to predict and remove for the higher frequency waveforms. Methods such as the inclusion of specific parametric measurements as a priori constraints to moment tensor inversion (Ford et al., 2012) and phase matched filtering to enhance signal-to-noise (unpublished work at AFRL) have been effective approaches that merit further development and application. Further development and application of such methods are sought.

References

>Stevens J.L. and S. Day (1985), “The physical basis of mb:Ms and variable frequency magnitude methods for earthquake/explosion discrimination”, Jour. Geophys. Res, 90, B4, DOI: 10.1029/JB090iB04p03009

>Ekström, G., M. Nettles, and A. M. Dziewonski (2012), “The global CMT project 2004-2010: Centroid-moment tensors for 13,017 earthquakes”, Phys. Earth Planet. Inter., 200-201, 1-9, 2012. doi:10.1016/j.pepi.2012.04.002

>Ford., S. R., W. R. Walter and D. S. Dreger (2012),  “Evendiscrimination using regional moment tensors with teleseismic-P constraints”, Bull. Seism. Soc Am., 102, 867-872, doi:10.1785/0120110227, 2012

>Ford, S.R., D.S. Dreger, and W.R. Walter (2009),  “Identifying isotropic events using a regional moment tensor inversion”, J. Geophys. Res., B01306, doi:10.1029/2008JB005743, 2009

Keywords: Seismology; Explosion; Earthquake; Moment Tensor   ; Phase Matched Filter; Discrimination

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.12.B8031: Energetic Particle Dtection, Data Analysis, and Modeling for Radiation Belt Studies

Selensnick, R.

(505) 846-5358

There is a need for improved methods for discriminating nuclear explosions from earthquakes and other natural and man-made seismic sources, and characterizing suspicious seismic sources. The technical challenges are driven by the need to monitor smaller events. Recordings of smaller events are generally sparser, made at closer distances (local and near regional), have lower signal-to-noise ratios, and have maximum signal amplitudes at higher frequencies than recordings of larger events. These differences all present challenges. Of the two most effective discriminants, phase ratio discriminants can fail at local distances and in areas with high attenuation, while the Ms:mb discriminant may not work for small shallow events (Stevens and Day, 1985). In addition, monitoring requirements evolve in response to geopolitical events, which drives a need to monitor in new regions that are often poorly calibrated both empirically and with respect to the resolution of available Earth models. The need to use higher frequency and lower signal-to-noise ratio waveforms for smaller events exacerbates the problems that arise from insufficient Earth model resolution. This drives a need for discriminants that are robust to high attenuation and limited means for removing propagation effects from seismic waveforms.

These requirements drive a need for extensions of existing discriminants to make them more effective for the challenging monitoring conditions described above, and for new discriminants that are effective for small events recorded sparsely at local and near regional distances. New methods will require a firm physical basis to support their application in new areas.  Inversion for regional moment tensors is currently an effective automated means (e.g. Ekström et al., 2012) of identifying earthquake focal mechanisms and for separating populations of different events types (Ford et al., 2009) at regional distances. Statistically rigorous uncertainty estimates however are needed, as are methods to improve resolution for smaller events, for which propagation effects are more difficult to predict and remove for the higher frequency waveforms. Methods such as the inclusion of specific parametric measurements as a priori constraints to moment tensor inversion (Ford et al., 2012) and phase matched filtering to enhance signal-to-noise (unpublished work at AFRL) have been effective approaches that merit further development and application. Further development and application of such methods are sought.

References:

Stevens J.L. and S. Day (1985), “The physical basis of mb:Ms and variable frequency magnitude methods for earthquake/explosion discrimination”, Jour. Geophys. Res, 90, B4, DOI: 10.1029/JB090iB04p03009

Ekström, G., M. Nettles, and A. M. Dziewonski (2012), “The global CMT project 2004-2010: Centroid-moment tensors for 13,017 earthquakes”, Phys. Earth Planet. Inter., 200-201, 1-9, 2012. doi:10.1016/j.pepi.2012.04.002

Ford., S. R., W. R. Walter and D. S. Dreger (2012),  “Event discrimination using regional moment tensors with teleseismic-P constraints”, Bull. Seism. Soc Am., 102, 867-872, doi:10.1785/0120110227, 2012

Ford, S.R., D.S. Dreger, and W.R. Walter (2009),  “Identifying isotropic events using a regional moment tensor inversion”, J. Geophys. Res., B01306, doi:10.1029/2008JB005743, 2009

Keywords:

Seismology; Explosion; Earthquake; Moment Tensor   ; Phase Matched Filter; Discrimination

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.12.B8021:Investigations into the vertical structure of Traveling Ionospheric Disturbance, their assimilation into ionospheric models, and their impacts on RF Propagation

Colman, J.

(505) 846-3172

The specification of ionospheric characteristics has a major impact on the operation of many important remote sensing and communication systems. The utility of climatological models in capturing the large scale features of the ionosphere, such as bulk seasonal or diurnal variations, is clear. More recently assimilative models of the ionosphere have been used extensively in this context and provide better real time or hindcast capabilities. It is now well known that beyond the large scale features of the ionosphere there exists a hierarchy of transient perturbations, some of which appear as coherent wave structures. The advent of high spatial density networks of GPS receivers, from which the total electron content (TEC) between the satellite and receiver can be determined, has made the observation such structures in TEC maps almost routine. Such wave structures have also been observed in many other ionospheric observational platforms such as all sky optical imager, Ionosonde, Incoherent Scatter Radar (ISR), and HF Doppler sounders. While there have been a few studies comparing the phenomenology of the different observational systems an integrated understanding of these features is still lacking.

Historically such coherent wave structures have been deemed Traveling Ionospheric Disturbances (TID). Such ionospheric disturbances are thought to originate from similar disturbances in the neutral atmosphere often called Traveling Atmospheric Disturbances (TAD). TIDs have typically been categorized into large scale (LSTID) and medium scale (MSTID). In general LSTIDs propagate quasi-horizontally with phase velocities in the 400-600 m/s range and wavelengths of 1000 km or more. They are associated with step changes to Joule heating in the auroral zone and have a strong correlation to the AE index. MSTIDs may have a vertical component to their propagation with phase velocities of 100-200 m/s and wavelengths of a few hundred kilometers. Their origins are typically described as stratospheric or below, e.g. orographic wind, convective systems, earthquakes, tsunamis. Their occurrence rates are still under investigation and range from a few percent to ubiquitous. Some of this disagreement stems from the different definitions and observational systems used to construct the climatologies. There are even smaller irregularities, traveling and otherwise and all of these structures coexist creating complex structures. Interpretation of such measurement prior to assimilation into a model requires some knowledge or assumptions about ionospheric structures, e.g. conversion of slant TEC into vertical TEC or performing an Abel transform on Radio Occultation data. Such interpretation can be complicated by the presence of TIDs and depends in part on the spatial or temporal characteristics of the measurement.

At AFRL we have recently executed, and have planned, a number of field experiments where multiple ionospheric measurement devices have been fielded together including: multiple Digisondes, all-sky imagers, a Fabre Perot Interferometer, Radio Beacon Receivers, HF spectrum analyzers, and GPS receivers. The Digisondes were often run at relatively high cadence and in oblique, or otherwise coordinated, modes. The proper multi-phenomenological interpretation of these data sets in terms of TIDs and TADs is of great interest for an improved understanding of their sources, vertical structure, and propagation characteristics as well as developing methods to understand their impact on assimilative models (or to assimilate them directly as coherent structures) and thereby their impact on RF propagation.

References

M. A. Cervera and T. J. Harris (2014) Modeling ionospheric disturbance features in quasi-vertically incident ionograms using 3-D magnetoionic ray tracing and atmospheric gravity waves, J. Geophys. Res., 119, 431-440, doi:10.1002/2013JA019247

R. Leitinger and M. Rieger (2005) The TID model for modulation of large scale electron density models, Ann. Geopys., 48, 3, 515-523

D. J. Livneh, I. Seker, F. T. Djuth, and J. D. Mathews, Omnipresent vertically coherent fluctuations in the ionosphere with a possible worldwide-midlatitude extent (2009), J. Geophys, Res., 114, doi:10.1029/2008JA013999

McNamara, L. F., C. R. Baker, and W. S. Borer (2009), Real-time specification of HF propagation support based on

a global assimilative model of the ionosphere, Radio Sci., 44, RS0A15, doi:10.1029/2008RS004004

McNamara, L. F., M. J. Angling, S. Elvidge, S. V. Fridman, M. A. Hausman, L. J. Nickisch, and L.-A.

McKinnell (2013), Assimilation procedures for updating ionospheric profiles below the F2 peak, Radio Sci., 48,

doi:10.1002/rds.20020

T. Ogawa, N. Balan, Y. Otsuka, K. Shiokawa, C. Ihara, T. Shimomai, and A. Saito (2002), Observations and modeling of 630 nm airglow and total electron content associated with traveling ionospheric disturbances over Shigaraki, Japan, Earth Planets Space, 54, 45-56

T. Tsugawa, Y. Otsuka, A. J. Coster, and A. Saito (2007), Medium-scale traveling ionospheric disturbances detected with dense and wide TEC maps over North America, Geophys. Res. Lett., 34, doi:10.1029/2007GL031663

>Keywords

Ionosphere; HF Propagation    ; Traveling Ionospheric Disturbance; Digisonde; GPS; Assimilative Modeling; TEC; Vertical Structures; System Impacts

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.12.B7961:Reactive Optimal and Robust Actuator Parameter Identification Control Allocation for Fault Tolerant Spacecraft Control

Weisman, R

(505) 846-5058

Due to the unconstrained nature of space, spacecraft have the ability for unconstrained motion about all 6 degree of freedom. This motion for many spacecraft missions must be predictable, precise, and in some instances agile.  Since spacecraft missions typically last for very long periods of time (i.e., typically on the order of 10-15 years), due to their high cost and long development schedules (i.e., also 10-15 years), the actuators hosted on-board spacecraft must maintain performance reliably over the same long time scale.  Some high fidelity models of spacecraft actuators due exist but unpredictable changes due to faults and/or anomalies still occur due to unknown reasons (e.g., mismodeled or stochastic space environment dynamics such as radiation effects and other factors such as a change in material properties due to temperature gradients or the initial vibration profile during spacecraft launch).  Most spacecraft systems contain a substantial amount of software, actuator, and sensor redundancy to account for these changes due to faults and/or anomalies but cannot foresee or adapt for all combinations of them in the software and do not react to these changes but rather put the spacecraft in safe mode and await a solution to the problem. Safe mode is not only a waste of mission time but also may be unsafe when changes have occurred to the spacecraft due to faults or anomalies. 

Therefore, true autonomy in guidance, navigation, and control (GN&C) is required for spacecraft missions that have complex GN&C objectives. With the recent use of code generation techniques in a slew of systems, software is produced in a more timely fashion but verification of the generated software still takes a significant portion of the assembly, integration, and testing (AI&T) of the 10-15 spacecraft development life. In addition, the software is typically only verified for foreseen faults and does not have the ability to rewrite or verify itself autonomously online when unforeseen changes due to faults and/or anomalies have occurred.  It is desired to have a GN&C system that has the ability to detect and isolate faults and/or anomalies, and react with a change to the navigation and control algorithms to optimize performance and verify that the software with the algorithm changes is safe and efficient.  All of these things should be done autonomously due to the risk of uploading flight code from the ground and the amount of time the spacecraft is nonfunctional after changes have occurred.

References

Robertson, Brent, and Eric Stoneking. "Satellite GN & C anomaly trends." Advances in the Astronautical Sciences 113 (2003): 531-542.

Dennehy, C., “The NASA Engineering & Safety Center (NESC) GN&C Technical Discipline Team (TDT):,” Technical Memorandum NASA/TM 2008-215128, National Aeronautics and Space Agency, 2008.

Keywords:

Spacecraft; Actuator; Control; Allocation; Fault; Anomaly; Optimal; Tolerant; Identification

Eligibility: Open to U.S. citizens Only

Level: Open to Regular and Senior applicants

SF.40.16.B0001: Baseband Diversity Product Approaches for Protected Wideband Satellite Communications

Pham, K

(505)-846-4823

Opportunities exist to explore Baseband Diversity Products (BDP) with flexibility options to operate in contested environments to maintain connectivity, improve link availability, reliability, and resilience, while at the same time confounding adversarial attempts to intercept and/or detect communications signals in wideband satellite communications. The implication of the diversity via satellite transponders, non-contiguous bandwidths, coverage beams, antenna polarizations, and multiple media, is that baseband traffics such as video, voice, and data could be disintegrated and integrated according to dedicated and/or opportunistic network path flows for optimal end-to-end latency, transmission reliability, information security, and bandwidth utilization. This topic seeks to develop new approaches for innovative data stream splitter supervised by link information feedback (e.g., data rates, latency, modulation, channel coding, etc.) and quality of services per applications; adaptive load balancing for multi-path routing and flow control with best efficiency and reliability; and agile code/frequency/time-hopping transmission patterns for satellite communications with low probability of detection and interception as well as multiple link flow security.

If successful, the BDP technologies anticipated for future terminal communications, which will be inserted in between routers and satellite modems, should be capable of i) supporting multiple network topologies for high speed data, voice, and video communications over terrestrial and satellite networks and ii) processing multiple streams simultaneously and interfacing with multiple commercial and military modems to support anti-jamming enhancement and ease of integration.

References:
1. X. Zhang, G. Wang, X. Tian, D. Shen, K. Pham, E. Blasch, and G. Chen.” Game-Theoretic Power Allocation and Waveform Selection for Satellite Communications”, SPIE Defense and Security, 2015
2. W. Yu, S. Wei, G. Xu, G. Chen, K. Pham, E. P. Blasch, and C. Lu, “On Effectiveness of Routing Algorithms for Satellite Communication Networks”, SPIE Defense, Security, and Sensing Symposium, 2013
3. W. Yu, X. Fu, E. Blasch, K. Pham, D. Shen, G. Chen, and C. Lu, “On Effectiveness of Hopping-Based Spread Spectrum Techniques for Network Forensic Traceback,” International Journal of Networked and Distributed Computing – Atlantis Press, 1(3), 2013

Keywords: Baseband Diversity Product, SATCOM, Terminal Communications, Data Fragmentation, Anti-Jamming, Flow Control, Link Information Feedback, Stream Splitter, Load Balancing, Data Rate, Latency, Jitter, Stream Status, Delay, Multi-path Routing, Quality of Services, Protection, Connectivity, Availability, Link Security

Eligibility: Open to U.S. citizens Only

SF.40.16.B0002: Cooperative Spectrum Sensing with Multi-Dimension Directions for Protected Tactical Satellite Communications

Pham, K

(505)-846-4823

As future satellite communications (SATCOM) networks will have access to an increasing amount of data, protected tactical services in contested environments will be enabled by cooperative spectrum sensing among distant user terminals, satellite control hubs, and other SATCOM networks. Sensing information exchange and fusion of throughput, data queue sizes, spectrum maps, signal-to-noise ratio information should be obtained with less overhead and more bandwidth efficiency. Uncertainty of sensing results and channel conditions also have large impacts on spectrum management for potential resolutions on miss-configurations and spectrum command and control.

Work focuses on this research topic related to necessary scientific foundations and design principles for affordability, within which cooperative spectrum sensing with multi-dimension directions; e.g., dynamic signal measurements, modulation classifications, and spectrum masks, must deal with a number of technical challenges in both network and physical layers for satellite carrier monitoring and reporting as well as radio interference and spectrum situational awareness. Given a concept of operations pertaining to multiple SATCOM terminals and ground hubs, opportunities are available to investigate, including but not limited to: (i) Cooperative spectrum sensing with information exchange and adaptive channel allocation schemes for efficient and effective estimations of carrier, noise, center frequency, bandwidth and other parameters; (ii) Machine learning with carrier-under-carrier case studies to determine elusive radio threats blending with intended signals; (iii) Alternatives with reduction of sensing overhead and energy cost for spectrum time-domain analysis such as max hold, min hold, and average power in channel; and (iv) Uncertainty analysis of sensing results in various channel conditions and interference types.

References:
1. R. A. Poisel, Modern Communications Jamming Principles and Techniques. Second edition, Artech House, 2011
2. H. Sun, A. Nallanathan, C. Wang, and Y. Chen, “Wideband Spectrum Sensing for Cognitive Radio Networks: A Survey,” IEEE Wireless Communications, Vol. 20, No. 2, pp. 74-81, 2013.
3. K. P. Murphy, “Machine Learning: A Probabilistic Perspective,” The MIT Press, 2012
4. X. Tian, Z. Tian, E. Blasch, et.al, “Sliding Window Energy Detection for Spectrum Sensing under Low SNR Conditions”, Wiley's Journal on Wireless Communications and Mobile Computing, 2015

Keywords: Satellite communications, protected tactical services, spectrum situational awareness, cooperative spectrum sensing, carrier, noise, modulation classification, spectrum mask, radio interferences, link layer, physical layer, signal measurement, spectrum efficiency, max hold, min hold, average power, energy efficiency, sensing efficiency, sensing accuracy, game theory, machine learning, uncertainty analysis

Eligibility: Open to U.S. citizens Only

SF.40.16.B0003: Communication Signaling and Signal Transmission in Low Probability of Interception Communications

Pham, K

(505)-846-4823

At the center of covertness and survivability issues of Low-Probability-Interception (LPI) communications is the development of communication signaling techniques and signal transmission schemes that are changing courses due to primarily to uncertain channel quality measurements, multi-access interferences, frequency-selective fading, partial band noise jamming, feedback delays, etc. Quantitatively speaking, it is important to investigate error performance analyses and related interpretations for M-ary-frequency-shift-keying systems employing L-hops per bit frequency hopping spread spectrum waveforms, transmitted over thermal noise plus partial-band Gaussian noise jamming channels. Performance measures should be computing processor dependent and further subject to different types of receiver processing techniques, e.g., square-law combining receiver, adaptively gain controlled square-law combining receiver, partially-jammed-hop elimination receiver, and clipped square-law combining receiver. A further concern involves hopping keystreams, which come from an end cryptographic unit at a user terminal. These frequency hopping patterns are more likely independent of channel conditions. In light of current practices, it becomes clear that the central question is then to ask whether or not L-hops per bit frequency hopping M-ary frequency-shift-keying spread spectrum systems with adaptive frequency hopping patterns ensure LPI communications more effectively; i.e., yielding of lower bit error rates, frame error rates against partial-band noise jamming under all possible operating situations? If yes, relevant technical challenges of developing adaptive frequency hopping patterns based on imperfect channel state information (CSI), jamming state information (JSI) in both time and frequency domains should be of interests. On another front, yet not too far removed from covert communications, possibly lies research and development of interest bearing on the scope of properly designing waveforms for LPI applications with two set of requirements: i) an unauthorized interceptor must not be able to detect the presence of the waveforms with probability greater than some specified small number – detection aspect; and ii) an authorized receiver can extract the information content with an acceptably low error probability – communication aspect.

References:
1. L. Schiavone and D. Hendry, “EHF Options for Contested SATCOM,” IEEE Military Communications Conference, MILCOM, 2011.
2. Y. Kawamoto, et.al., “Prospects and Challenges of Context-Aware Multimedia Content Delivery in Cooperative Satellite and Terrestrial Networks,” IEEE Communication Magazine, 2014.
3. S. Lambotharan and A. Panoui, “Game-Theoretic Framework for Radar Waveform Design,” 2014.
4. G. Wang, K. Pham, E. Blasch, T. M. Nguyen, G. Chen, et. al., “Optimum design for robustness of frequency hopping system,” IEEE Military Communications Conference, 2014.

Eligibility: Open to U.S. citizens Only

SF.40.17.B0001: Spacecraft Materials Properties for Spacecraft Charging

Ferguson, Dale C

(505)-846-1566

This opportunity consists of measuring, analyzing, and evaluating spacecraft materials properties that have a direct bearing on spacecraft charging (i.e., bulk and surface resistivities, dielectric constants, secondary electron emission, and photoemission). Measurements of materials properties and/or charging of materials under electron beam irradiation will be made using laboratory facilities at the Kirtland Air Force Base in Albuquerque, New Mexico. Special attention will be paid to changes of materials properties and spacecraft charging with temperature, contamination, radiation dose, and/or vacuum aging.

Keywords: Spacecraft charging; Materials properties; Space environment;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.17.B0002: Advanced Space-based Imaging Field Campaigns, Data Analyses and Cloud Characterization

Pereira, Wellesley E.

(505)-853-3624

This effort focuses on planning, conducting, and analyzing data collection events from an extended space-based imaging campaign using an advanced remote-sensing methodology developed at the AFRL Space Vehicles Directorate. This data collection campaign (which leverages space-based imagery of ground events, with ground-based truth sensors) is intended to help validate unique methods in advanced infrared sensing, and as such must take place under carefully-monitored conditions, at specific locations in the world. The field campaign will consist of coordinated data collection events using exquisite sensing assets to observe high-radiance, short-duration events, which necessitates careful advance planning. Coordination of practical details, including timing of events, coordination of assets, collaboration with domestic and international partners, and management of data collection requirements, is important to this effort.

Furthermore, uncertainties associated with the presence of clouds when imaging from space have to be taken into consideration. To accomplish this goal, a diverse network of retrieved measurements must be statistically data mined from both up- and down-looking sensors. These include the following:

  1. AERONET (Aerosol Robotic Network), a network of globally distributed instruments which operate in a cloud-mode acquisition and measure a variety of atmospheric and cloud parameters, including cloud optical depths between 10 and 90.
  2. Micro Pulse Lidar Network (MPLNET) which measures aerosol cloud vertical structure continuously, day and night.
  3. Ceilometers at major airports which provide cloud base heights.
  4. MODIS Cloud Product, a global product that provides cloud particle-phase, effective cloud particle radius, and cloud optical thickness.
  5. Other global satellite cloud datasets as needed.

The various datasets are needed to resolve the point source measurements (AERONET, MIPLNET and ceilometers) to the satellite kilometer-scale footprints. Researching and resolving the highlighted issues requires a solid background in programming and atmospheric physics to perform data mining techniques and develop algorithms appropriate for effective cloud optical depth retrievals. Additionally, skills in data analysis, including implementing advanced analysis routines and conducting comparative analyses, are important, as is an ability to communicate technical material in writing or orally. Key technical background areas include electro-optical sensors, infrared imaging, cloud physics and/or atmospheric transmission, as well as hands-on experience. Additionally, an ability to travel to field locations is desirable.

Keywords: Advanced imaging; Space-based imaging; Cloud statistics; Cloud optical depth; Atmospheric transmission;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.17.B0003: Characterization of Hyperspectral Imagers

Schieffer, Stephanie L

(505)-853-3959

Our research group conducts studies of innovative techniques for calibrating and characterizing the radiometric performance of hyperspectral imaging (HSI) sensors flown on airborne platforms and satellites. HSI have numerous applications in part because the data takes the form of a hypercube containing two spatial and one spectral dimension, thereby providing significantly more information than a panchromatic image. Our interest in HSI sensors is motivated by the need to exploit high fidelity HSI data. Thus, the research we conduct centers around developing rapid, mobile, and accurate (less than 3% uncertainty) radiometric, spectral, and spatial characterization methods utilizing state-of-the-art instrumentation, including supercontinuum fiber lasers and optical parametric oscillators (OPOs). We are currently applying experimental methods and theoretical ideas to develop methods for measuring spectral scattering in both the spectral and spatial dimension for HSI sensors. In addition, we calibrate deployable sensors using both standard techniques and our newly developed methods to generate correction matrices and tensors. We are also interested in developing hyperspectral calibration techniques for the long wave infrared (LWIR). This work provides important data for the validation of optical scatter models that inform the design and development of next-generation sensors.

References

Zong Y, et al: Applied Optics 45: 1111-1119, 2006

McCorkel J, Thome K, Lockwood RB: IEEE Transactions on Geoscience and Remote Sensing 5: 1309-1318, 2013

Keywords: Photonics; Lasers; Optics; Ground calibration; On-orbit calibration; Sensors;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.17.B0004: Development of Ultrahigh Temperature Chemistry Models for Hypersonic Flow

Bemish, Raymond J

(505)-853-2776

Atmospheric reentry vehicles produce large amounts of heat and plasma due to the high Mach number. This process is primarily driven by the non-equilibrium high-temperature chemistry that is present in the bow-shock and the gas surface interactions. Due to the high temperature, in excess of 20,000K, it is difficult to experimentally derive meaningful values. A combination of theory and flight/ground test data is used to validate these models. For this reason, it is necessary to develop physics based models for all of the drivers in hypersonic flight and use the combined effects to produce a high fidelity simulation of the flight. This allows for optimization and validation of the chemical models. This effort supports development of all the constituent physics and chemistry for a high fidelity hypersonic flight solution.

Keywords: Spacecraft; Actuator; Control; Allocation; Fault; Anomaly; Optimal; Tolerant; Identification;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.17.B0005: Fundamental Investigation of Plasma Chemistry Kinetics and Dynamics towards Improved Communications Abilities

Shuman, Nicholas A

(505)-853-3966

The propagation, refraction, or reflection of radio waves through weakly ionized plasma (e.g., the natural ionosphere) is most succinctly understood by comparison of the frequency of the radio wave to the critical frequency of the plasma, a function of the electron density. The electron density in turn is determined by the chemistry of charged species present in the plasma. Decades of research into the ion chemistry of the ambient ionosphere have provided a solid foundation for modeling and prediction of radio wave propagation under a range of conditions. More recent interest has been focused on “artificial” ionospheric conditions, either those produced incidentally by effects of hypersonic objects (e.g., re-entry vehicles) or those produced intentionally via ionospheric modification. Much of the basic chemistry under the temperature and pressure conditions required to model these environments is unstudied. This includes ion-molecule, electron attachment, mutual neutralization, and dissociative recombination processes at elevated temperatures, a range of pressures, and over non-thermal conditions.

We are particularly interested in reactions resulting in spontaneous ionization, offering a means to increase the local electron density over a region of the lower ionosphere. A number of the lanthanide rare earth metals along with a handful of transition metals possess energetics where chemi-ionization (e.g., A + B → AB+ + e) is exothermic with either atomic oxygen or oxygen-containing species. Release of these metals in the E-region of the ionosphere, where atomic oxygen is a dominant neutral species, provides an avenue to creating a cloud of enhanced electron density. However, the kinetics of these processes has been only minimally explored and the energy dependences generally unexplored. Additionally, the related ion chemistry is in nearly all cases unknown. Vaporization of these metals in an oven source coupled to a flow tube reactor provides a route to studying the chemi-ionization kinetics and products. Electrospray ionization of solutions of these metals allows for production of the ionized metal and metal oxides in the gas phase, and determination of the kinetics of those species through standard techniques. The results of these measurements can be directly transitioned to models of chemical releases in the ionosphere, aiming to account for both the associated physics and chemistry, to interpret results of prior chemical release experiments and to determine the relative efficacy of different species under consideration for future experiments.

References

Shuman NS, Hunton DE, Viggiano A: Ambient and modified atmospheric ion chemistry: From top to bottom. Chemical Reviews 115: 4542-4570, 2015 Cox RM, et al: Evaluation of the exothermicity of the chemi-ionization reaction Sm + O → SmO+ + e-. The Journal of Chemical Physics 142: 134307, 2015

Keywords: Plasma chemistry; Ionosphere; Electron attachment; Chemical physics; Radicals; Ion-molecule; Flow tube; Kinetics; Dissociative recombination;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.17.B0006: Ionosphere-Thermosphere Coupling-Data Analysis and Numerical Simulations

Huang, Cheryl Y

(505)-846-7218

Understanding the Ionosphere-Thermosphere (IT) system is crucial for accurate forecasting of the impact of space weather. We solicit proposals to investigate high-latitude IT coupling via a combination of data analysis and numerical simulations during conditions of solar wind forcing. Data analysis should include sources from ground and space to be as comprehensive as possible. We encourage innovative physics-based model solutions aimed at improving forecast ability in real time. Model results should be validated by comparison with data.

References

Huang CY, et al: Ionosphere-thermosphere (IT) response to solar wind forcing during magnetic storms. Journal of Space Weather and Space Climate 6 A4: 2015, doi: 10.1051/swsc/2015041 Huang CY, et al: Energy coupling during the August 2011 magnetic storm. Journal of Geophysical Research: 1219-1232, 2014, doi: 10.1002/2014JA019297 Huang Y, Huang CY, et al: Ionization due to electron and proton precipitation during the August 2011 storm. Journal of Geophysical Research, doi:10.1002/2013JA019671 2014

Keywords: Ionosphere; Thermosphere; Solar wind forcing; Space weather; Physics-based models; High-latitude IT coupling;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

SF.40.01.B0007: AFRL Spacecraft Performance Analytics and Computing Environment Research

Mee, Jesse K

(505)-846-3749

The current methods for the identification of future technological capabilities required to support next-generation DOD systems lack the quantitative sophistication and detail needed to compare system gains resulting from Size, Weight and Power (SWaP) and performance improvements at the device/component level. Furthermore, owing to the increasing complexity of modern computing architectures, there is no longer a trivial approach toward selection of onboard hardware resources necessary to meet future Air Force mission needs. To address these concerns, the Air Force Research Laboratory (AFRL) has recently established a dedicated architecture test-bed under the Spacecraft Performance Analytics and Computing Environment Research (SPACER) project. This test-bed allows researchers to address the increasing challenge of mapping mission requirements to hardware and software implementations for space computing applications. This multifaceted project provides multiple challenging research opportunities for an enthusiastic applicant. In particular, we are seeking support with identification and design of the optimized heterogeneous computing architecture for a specialized mission application code. This effort will require decomposition of the application code into a sum of its low level computational pieces (e.g., FFT, Matrix-Matrix multiply), benchmarking of those computational pieces on the test-bed hardware resources, and design of an optimized hardware platform for the mission. In another effort, we seek to develop a satellite system level model that enables creation of a performance trade-space characterizing top-level mission impacts as a function of modifications at the individual component level. This model allows the user to capture the satellite component hierarchy, define the complex time-varying power characteristics, and propagate the model through an orbital simulation to study the on-orbit energy utilization of the candidate architecture. If executed properly, this effort will provide a valuable capability to the Air Force, enabling a more quantitative approach to justification of future research investments, in addition to a better understanding of computational requirements for next generation mission applications

References

Pineda AC, Mee JK, et al: Benchmarking Image Processing for Space: Introducing the SPACER Architecture Laboratory. IEEE Aerospace, Accepted (2016) Mee JK, et al: Energy Accounting Model for Hardware Impact Analysis. IEEE Aerospace, Accepted (2016)

Keywords: Spacecraft; Embedded system; Computer; Architecture; Model; Simulation; Efficiency; Performance; Optimization;

Eligibility: Open to U.S. citizens Only

Level: Open to Postdoctoral and Senior applicants

AFRL/Space Vehicles

Dr. Greg Spanjers, Chief Scientist
AFRL/RV
3550 Aberdeen Avenue SE
Kirtland Air Force Base, New Mexico 87117
Telephone: (505) 846-9330
E-mail: gregory.spanjers@us.af.mil
Mr. Eugene Fosness
AFRL/RV
3550 Aberdeen Avenue SE
Kirtland Air Force Base, New Mexico 87117
Telephone: (505) 846-1790
E-mail: eugene.fosness@us.af.mil