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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2010

The Landsat Data Continuity Mission Operational Land Imager (OLI) Radiometric Calibration

The Operational Land Imager (OLI) on the Landsat Data Continuity Mission (LDCM) has a comprehensive radiometric characterization and calibration program beginning with the instrument design, and extending through integration and test, on-orbit operations and science data processing. Key instrument design features for radiometric calibration include dual solar diffusers and multi-lamped on-board calibrators. The radiometric calibration transfer procedure from NIST standards has multiple checks on the radiometric scale throughout the process and uses a heliostat as part of the transfer to orbit of the radiometric calibration. On-orbit lunar imaging will be used to track the instruments stability and side slither maneuvers will be used in addition to the solar diffuser to flat field across the thousands of detectors per band. A Calibration Validation Team is continuously involved in the process from design to operations. This team uses an Image Assessment System (IAS), part of the ground system to characterize and calibrate the on-orbit data.

Markham, Brian L.↗
NASA NTRS2010

Monolithically Integrated, Mechanically Resilient Carbon-Based Probes for Scanning Probe Microscopy

Scanning probe microscopy (SPM) is an important tool for performing measurements at the nanoscale in imaging bacteria or proteins in biology, as well as in the electronics industry. An essential element of SPM is a sharp, stable tip that possesses a small radius of curvature to enhance spatial resolution. Existing techniques for forming such tips are not ideal. High-aspect-ratio, monolithically integrated, as-grown carbon nanofibers (CNFs) have been formed that show promise for SPM applications by overcoming the limitations present in wet chemical and separate substrate etching processes.

Kaul, Anupama B.↗
NASA NTRS2010

Energy Management of the Multi-Mission Space Exploration Vehicle Using a Goal-Oriented Control System

Safe human exploration in space missions requires careful management of limited resources such as breathable air and stored electrical energy. Daily activities for astronauts must be carefully planned with respect to such resources, and usage must be monitored as activities proceed to ensure that they can be completed while maintaining safe resource margins. Such planning and monitoring can be complex because they depend on models of resource usage, the activities being planned, and uncertainties. This paper describes a system - and the technology behind it - for energy management of the NASA-Johnson Space Center's Multi-Mission Space Exploration Vehicles (SEV), that provides, in an onboard advisory mode, situational awareness to astronauts and real-time guidance to mission operators. This new capability was evaluated during this year's Desert RATS (Research and Technology Studies) planetary exploration analog test in Arizona. This software aided ground operators and crew members in modifying the day s activities based on the real-time execution of the plan and on energy data received from the rovers.

Braman, Julia M. B.↗
NASA NTRS2010

Ultra-Wideband Angle-of-Arrival Tracking Systems

Systems that measure the angles of arrival of ultra-wideband (UWB) radio signals and perform triangulation by use of those angles in order to locate the sources of those signals are undergoing development. These systems were originally intended for use in tracking UWB-transmitter-equipped astronauts and mobile robots on the surfaces of remote planets during early stages of exploration, before satellite-based navigation systems become operational. On Earth, these systems could be adapted to such uses as tracking UWB-transmitter-equipped firefighters inside buildings or in outdoor wildfire areas obscured by smoke. The same characteristics that have made UWB radio advantageous for fine resolution ranging, covert communication, and ground-penetrating radar applications in military and law-enforcement settings also contribute to its attractiveness for the present tracking applications. In particular, the waveform shape and the short duration of UWB pulses make it possible to attain the high temporal resolution (of the order of picoseconds) needed to measure angles of arrival with sufficient precision, and the low power spectral density of UWB pulses enables UWB radio communication systems to operate in proximity to other radio communication systems with little or no perceptible mutual interference.

Arndt, G. Dickey↗
NASA NTRS2011

Noble Gas Analysis in the Quest to Find "Regolithic" Howardites

The howardite meteorites consist of approximately 200 polymict breccias of eucrite (basaltic) and diogenite (orthopyroxenitic) material (collectively, the HED group) that originate from the asteroid belt. Infrared reflectance spectroscopy of asteroids and laboratory studies of HEDs have indicated that the asteroid 4-Vesta is the likely parent body, and the partially-demolished south pole may be the source region. Asteroid regolith formation processes may be responsible for a number of observed petrological features including impact melt clasts, reworked clasts and mosaisicm. We have identified such features in a study of 30 howardites and polymict eucrites, and developed a regolith grading scheme based on petrology. However, the true regolithic nature of the howardite suite is not well defined, and previous research has suggested correlations between Ni contents of 300 - 1200 micron / g, a minimal variation in Al2O3 content around 8-9 wt% and the presence of solar wind noble gases are key hallmarks of an ancient regolith on Vesta . Through combined petrological, compositional and noble gas research, we aim to better understand howardite petrological diversity, regolith formation processes on parent asteroids, and to establish what defines a truly "regolithic" howardite. Our research will play an integral part in the interpretation of data gathered by the Dawn mission. Here we report the preliminary results from our noble gas analyses of four howardites: LEW 85313, EET 99408, MET 96500 and PCA 02066. Bulk major element compositional data have been collected, further petrological data for the HED group are reported by our colleagues, whilst trace-element analyses are underway. Our work will investigate the extent of whether previously described Ni, Al2O3 and noble gas characteristics are in fact indicative of a "regolithic" howardite.

Cartwright, Julia A.↗
NASA NTRS2010

GSFC Heliophysics Science Division FY2010 Annual Report

This report is intended to record and communicate to our colleagues, stakeholders, and the public at large about heliophysics scientific and flight program achievements and milestones for 2010, for which NASA Goddard Space Flight Center's Heliophysics Science Division (HSD) made important contributions. HSD comprises approximately 323 scientists, technologists, and administrative personnel dedicated to the goal of advancing our knowledge and understanding of the Sun and the wide variety of domains that its variability influences. Our activities include: Leading science investigations involving flight hardware, theory, and data analysis and modeling that will answer the strategic questions posed in the Heliophysics Roadmap; Leading the development of new solar and space physics mission concepts and support their implementation as Project Scientists; Providing access to measurements from the Heliophysics Great Observatory through our Science Information Systems; and Communicating science results to the public and inspiring the next generation of scientists and explorers.

Gilbert, Holly R.↗
NASA NTRS2011

Ionic Liquids to Replace Hydrazine

A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

Koelfgen, Syri↗
NASA NTRS2011

"Solar-Wind-Rich" Howardite: True Regolith vs. CM-Implanted Components

Howardite, eucrite and diogenite meteorites (collectively HED) likely originate from asteroid 4-Vesta [1], one of two asteroids targeted by NASA s Dawn mission. Many howardites (polymict breccias of E and D material) contain "regolithic" features, including impact-melt clasts, fragmental breccia clasts, and carbonaceous chondrite fragments. True regolithic nature can be determined through noble gas analysis, as Solar Wind (SW) is implanted into the upper-most surfaces of solar system bodies. Whilst previous work [2] suggested that high siderophile element contents (e.g. Ni of 300-1200 g/g) were regolith indicators, we found no obvious correlation between SW and these indicators in our initial howardite noble gas analyses [3]. We observed CM-like fragments in a number of our howardites, whose textures suggest late addition to the breccia assemblage [4]. As typical CMs contain mixtures of SW (in matrix) and planetary (in clasts) components [5], we investigate the dominance of such components in SW-rich howardites. This will help deter-mine the extent of implanted SW in HED grains vs. SW and planetary gases from CM fragments, and allow better understanding of regolith processes

Cartwright, Julia A.↗
NASA NTRS2011

A Multiwavelength Study of Cygnus X-1: The First Mid-Infrared Spectroscopic Detection of Compact Jets

We report on a Spitzer/IRS (mid-infrared), RXTE /PCA+HEXTE (X-ray), and Ryle (radio) simultaneous multi-wavelength study of the micro quasar Cygnus X-I, which aimed at an investigation of the origin of its mid-infrared emission. Compact jets were present in two out of three observations, and we show that they strongly contribute to the mid-infrared continuum. During the first observation, we detect the spectral break - where the transition from the optically thick to the optically thin regime takes place - at about 2.9 x 10(exp 13) Hz. We then show that the jet's optically thin synchrotron emission accounts for the Cygnus X-1's emission beyond 400 keY, although it cannot alone explain its 3-200 keV continuum. A compact jet was also present during the second observation, but we do not detect the break, since it has likely shifted to higher frequencies. In contrast, the compact jet was absent during the last observation, and we show that the 5-30 micron mid-infrared continuum of Cygnus X-I stems from the blue supergiant companion star HD 226868. Indeed, the emission can then be understood as the combination of the photospheric Raleigh-Jeans tail and the bremsstrahlung from the expanding stellar wind. Moreover, the stellar wind is found to be clumpy, with a filling factor f(sub infinity) approx.= 0.09-0.10. Its bremsstrahlung emission is likely anti-correlated to the soft X-ray emission, suggesting an anticorrelation between the mass-loss and mass-accretion rates. Nevertheless, we do not detect any mid-infrared spectroscopic evidence of interaction between the jets and the Cygnus X-1's environment and/or companion star's stellar wind.

Rahoui, Farid↗
NASA NTRS2011

Landing gear noise attenuation

A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

Moe, Jeffrey W.↗
NASA NTRS2010

Twenty-Five Years of Landsat Thermal Band Calibration

Landsat-7 Enhanced Thematic Mapper+ (ETM+), launched in April 1999, and Landsat-5 Thematic Mapper (TM), launched in 1984, both have a single thermal band. Both instruments thermal band calibrations have been updated previously: ETM+ in 2001 for a pre-launch calibration error and TM in 2007 for data acquired since the current era of vicarious calibration has been in place (1999). Vicarious calibration teams at Rochester Institute of Technology (RIT) and NASA/Jet Propulsion Laboratory (JPL) have been working to validate the instrument calibration since 1999. Recent developments in their techniques and sites have expanded the temperature and temporal range of the validation. The new data indicate that the calibration of both instruments had errors: the ETM+ calibration contained a gain error of 5.8% since launch; the TM calibration contained a gain error of 5% and an additional offset error between 1997 and 1999. Both instruments required adjustments in their thermal calibration coefficients in order to correct for the errors. The new coefficients were calculated and added to the Landsat operational processing system in early 2010. With the corrections, both instruments are calibrated to within +/-0.7K.

Barsi, Julia A.↗
NASA NTRS2011

Landsat-7 ETM+: 12 years On-Orbit Reflective-Band Radiometric Performance

The Landsat-7 ETM+ sensor has been operating on orbit for more than 12 years and characterizations of its performance have been ongoing over this period. In general, the radiometric performance of the instrument has been remarkably stable: (1) Noise performance has degraded by 2% or less overall, with a few detectors displaying step changes in noise of 2% or less, (2) Coherent noise frequencies and magnitudes have generally been stable, though the within-scan amplitude variation of the 20kHz noise in bands 1 and 8 disappeared with the failure of the scan line corrector and a new similar frequency noise (now about 18kHz) has appeared in two detectors in band 5 and increased in magnitude with time, (3) Bias stability has been better than 0.25 DN out of a normal value of 15 DN in high gain, (4) Relative gains, the differences in response between the detectors in the band, have generally changed by 0.1% or less over the mission, with the exception of a few detectors with a step response change of 1% or less and (5) Gain stability averaged across all detectors in a band, which is related to the stability of the absolute calibration, has been more stable than the techniques used to measure it. Due to the inability to confirm changes in the gain (beyond a few detectors that have been corrected back to the band average), ETM+ reflective band data continues to be calibrated with the pre-launch measured gains. In the worst case some bands may have changed as much as 2% in uncompensated absolute calibration over the 12 years.

Markham, Brian L.↗
NASA NTRS2011

Towards Autonomous Operation of Robonaut 2

The Robonaut 2 (R2) platform, as shown in Figure 1, was designed through a collaboration between NASA and General Motors to be a capable robotic assistant with the dexterity similar to a suited astronaut [1]. An R2 robot was sent to the International Space Station (ISS) in February 2011 and, in doing so, became the first humanoid robot in space. Its capabilities are presently being tested and expanded to increase its usefulness to the crew. Current work on R2 includes the addition of a mobility platform to allow the robot to complete tasks (such as cleaning, maintenance, or simple construction activities) both inside and outside of the ISS. To support these new activities, R2's software architecture is being developed to provide efficient ways of programming robust and autonomous behavior. In particular, a multi-tiered software architecture is proposed that combines principles of low-level feedback control with higher-level planners that accomplish behavioral goals at the task level given the run-time context, user constraints, the health of the system, and so on. The proposed architecture is shown in Figure 2. At the lowest-level, the resource level, there exists the various sensory and motor signals available to the system. The sensory signals for a robot such as R2 include multiple channels of force/torque data, joint or Cartesian positions calculated through the robot's proprioception, and signals derived from objects observable by its cameras.

Badger, Julia M.↗
NASA NTRS2011

Formal Verification Toolkit for Requirements and Early Design Stages

Efficient flight software development from natural language requirements needs an effective way to test designs earlier in the software design cycle. A method to automatically derive logical safety constraints and the design state space from natural language requirements is described. The constraints can then be checked using a logical consistency checker and also be used in a symbolic model checker to verify the early design of the system. This method was used to verify a hybrid control design for the suit ports on NASA Johnson Space Center's Space Exploration Vehicle against safety requirements.

Badger, Julia M.↗
NASA NTRS2011

Understanding Space Weather: The Sun as a Variable Star

The Sun is a complex system of systems and until recently, less than half of its surface was observable at any given time and then only from afar. New observational techniques and modeling capabilities are giving us a fresh perspective of the solar interior and how our Sun works as a variable star. This revolution in solar observations and modeling provides us with the exciting prospect of being able to use a vastly increased stream of solar data taken simultaneously from several different vantage points to produce more reliable and prompt space weather forecasts. Solar variations that cause identifiable space weather effects do not happen only on solar-cycle timescales from decades to centuries; there are also many shorter-term events that have their own unique space weather effects and a different set of challenges to understand and predict, such as flares, coronal mass ejections, and solar wind variations

Strong, Keith↗
NASA NTRS2012

Advancing Robotic Control for Space Exploration Using Robonaut 2

Robonaut 2, or R2, arrived on the International Space Station (ISS) in February 2011 and is currently being tested in preparation for its role initially as an Intra-Vehicular Activity (IVA) tool and eventually as a robot that performs Extra-Vehicular Activities (EVA). Robonaut 2, is a state of the art dexterous anthropomorphic robotic torso designed for assisting astronauts. R2 features increased force sensing, greater range of motion, higher bandwidth, and improved dexterity over its predecessor. Robonaut 2 is unique in its ability to safely allow humans in its workspace and to perform significant tasks in a workspace designed for humans. The current operational paradigm involves either the crew or the ground control team running semi-autonomous scripts on the robot as both the astronaut and the ground team monitor R2 and the data it produces. While this is appropriate for the check-out phase of operations, the future plans for R2 will stress the current operational framework. The approach described here will outline a suite of operational modes that will be developed for Robonaut 2. These operational modes include teleoperation, shared control, directed autonomy, and supervised autonomy, and they cover a spectrum of human involvement in controlling R2.

Badger, Julia↗
NASA NTRS2012

Ultrawideband asynchronous tracking system and method

A passive tracking system is provided with a plurality of ultrawideband (UWB) receivers that is asynchronous with respect to a UWB transmitter. A geometry of the tracking system may utilize a plurality of clusters with each cluster comprising a plurality of antennas. Time Difference of Arrival (TDOA) may be determined for the antennas in each cluster and utilized to determine Angle of Arrival (AOA) based on a far field assumption regarding the geometry. Parallel software communication sockets may be established with each of the plurality of UWB receivers. Transfer of waveform data may be processed by alternately receiving packets of waveform data from each UWB receiver. Cross Correlation Peak Detection (CCPD) is utilized to estimate TDOA information to reduce errors in a noisy, multipath environment.

Arndt, G. Dickey↗
NASA NTRS2012

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron

Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and their relative temporal relationships. This study focused on sinuous channels located on the south-east part of the Ascraeus rift apron (Fig. 1). Observations of possible analogous features on Hawaii are used to provide insights into the processes of formation of the Mars features.

Signorella, Julia D.↗