Search NASA⌕ Search

SEARCH · Search NASA

Results for “In-Flight Icing”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

161 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

In-Flight Thermal Performance of the OCO-2 Instrument

The Orbiting Carbon Observatory-2 (OCO-2), launched on July 2, 2014, continues to operate nominally after successfully completing its primary mission of two years in space. It is hoped that, following a Senior Review and proposal phase, NASA will fund a two year extended mission, which would start in June 2017. The thermal design provides three temperature zones required by the instrument, specifically at 120 K, 267 K and 297 K. A single-stage pulse tube cryocooler provides refrigeration to three focal plane arrays to 120 K, via a high conductance flexible thermal strap. A variable conductance heat pipe (VCHP) based heat rejection system transports waste heat from the instrument, located inside the spacecraft, to the space-viewing radiators, providing tight temperature control of the spectrometer optics to 267 K, and maintains the electronics and cryocooler at 297 K. Soon after entering the A-Train on August 3, 2014, the optics and focal planes were cooled to their operating temperatures. Ice contamination of the cryogenic surfaces led to increased cryocooler loads and drove the need for two focal plane decontamination cycles between September 2014 and October 2014. A decrease in the radiometric gain of the O2 A-Band channel led to five additional focal plane decontamination cycles, between January 2015 and February 2017, and is now the primary driver of decontamination cycles. This paper provides a general overview of the thermal and cryogenic system design and reviews the inflight thermal performance for the mission.

Na-Nakornpanom, Arthur↗
DOE OSTI2020

Physics Division Strategic Plan Fiscal Years 2020-2024

The vision of the Physics Division (PHY) at Argonne National Laboratory is to continue enhancing its role as a world-leading institution in basic nuclear physics research and its applications. Key to this vision is for PHY to continue to safely and effectively operate and evolve the capabilities of the Argonne Tandem Linac Accelerator System (ATLAS) facility to best serve its users. ATLAS is the Department of Energy (DOE) accelerator facility for low-energy nuclear physics research. The research carried out by PHY covers many themes in contemporary science but can be distilled into five areas of focus. These themes are interconnected, with continuously evolving synergies between the various groups and facilities in PHY and the broader Laboratory. This five-year strategic plan serves to illustrate our current capabilities and new directions related to these five areas of focus (ATLAS also develops an independent strategic plan): Accelerator research and design. The goal of this theme is to design, fabricate, test, and implement novel accelerator systems, with a focus on high-intensity ion and electron systems. These R&D activities have led to enhancements in the ATLAS accelerator system. Among others, the division’s accelerator systems are in use or planned for use at Fermilab, the Advanced Photon Source, and in a broad variety of applications at the Facility for Rare Isotope Beams (FRIB). Atom trapping and fundamental symmetries. The goal of this theme is to explore and exploit the uses of advanced laser cooling and trapping techniques to manipulate atoms. There are three main areas of focus. First is in the application of the atom trap trace analysis (ATTA) technique for age determination of groundwater and ice by using radio-krypton dating. The next two trapping-based programs involve tests of fundamental symmetries in nature: the cooling and trapping of radium-225 with the aim of determining limits on an observation of its electric dipole moment and precision measurements of the beta decay properties of helium-6 to set limits on the tensor coupling constant. This is complemented by measurements of similar properties in lithium-8 and boron-8. Nuclear astrophysics. The goal of this theme is to enhance our understanding of how elements are created in the universe via explosive nucleosynthesis and how stars evolve. To meet the challenges of this theme, many of the capabilities of ATLAS are being enhanced, including the development of new beams through a new in-flight separator (RAISOR) and the anticipated neutron-generator upgrade of the Californium Rare Isotope Breeder Upgrade facility (nuCARIBU). These are coupled to state-of-the-art instruments such as the Canadian Penning Trap, Helical Orbit Spectrometer, Gammasphere, GRETINA, Multi-Sampling Ionization Chamber, the Fragment Mass Analyzer, and Argonne Gas-filled Fragment Analyzer, and a new low-background experimental area for decay studies. Nuclear structure. The goal of this theme is to understand the structure of nuclei, both stable and radioactive, in terms of single-particle properties, their shapes, and the dynamics governing reactions between them. These include questions such as what are the limits of nuclear stability and what are the properties of super heavy nuclei. As with the nuclear astrophysics theme, the capabilities of ATLAS, guided by the ATLAS user community, are continuously being enhanced to this end. The Division has strategic initiatives to play a leading role in the development of instrumentation and research programs at the FRIB. Quantum chromodynamics (QCD) and hadron physics. The goal of this theme is to lead major research programs focused on revealing the quark and gluon structure of protons, neutrons, nuclei, and short-lived mesons and baryons. These involve major programs at Jefferson Lab, Fermilab, and smaller facilities. They are complemented by theoretical endeavors centered on the question of how hadrons and their properties emerge from QCD. Out of these activities arise strategic initiatives to play a major role in the forthcoming Electron-Ion Collider (EIC).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2022

Night Sky Testing of the Lunar Flashlight Star Tracker

Lunar Flashlight (LF) is a 6U, 14 kg spacecraft being built by the NASA Jet Propulsion Laboratory (JPL). The mission will use IR laser technology to search for volatiles and surface water ice deposits in the permanently shadowed regions (PSR) of the moon in preparation for future human lunar exploration. The fine pointing provided by the Guidance, Navigation and Control (GNC) system is crucial for the spacecraft to successfully reach the moon, enter a lunar orbit, and acquire scientific data. At the center of the GNC system’s ability to determine the spacecraft’s attitude is a star tracker. The LF star tracker is a commercial-off-the-shelf (COTS) unit built into the integrated GNC system provided by Blue Canyon Technologies. Blue Canyon tested the star tracker in a lab environment for basic functionality and attitude estimation capabilities; upon delivery of the hardware to JPL, further testing with a real night sky was desired to determine expected in-flight operational characteristics. JPL maintains the Table Mountain Facility with its suite of ground telescopes, including a 0.6m telescope with an equatorial mount. This stable platform provided a highly accurate method of providing slews and attitude holds akin to what the spacecraft will perform in flight. Therefore, by analyzing the data from these representative night-sky ground tests performed in March, 2021, it is possible to acquire expected flight performance of the star tracker, particularly in regard to the ability of the star tracker to maintain lock on the starfield during planned maneuver types. This paper presents the various tests that have been performed to ensure that the LF star tracker will function as part of the overall GNC system and integrated spacecraft once launched. Test data is included for several key tests, and a path forward towards future integration and testing at the spacecraft level is described.

Baker, John↗
NASA NTRS1999

Investigating the Martian Environment with the Mars Global Surveyor Thermal Emission Spectrometer

The Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor (MGS) is being used to investigate the surface and atmosphere of Mars and the martian moons Phobos and Deimos. As such, it builds upon infrared observations obtained by previous spacecraft, e.g.. Mariner 9 and Viking Orbiters. The objectives of the TES experiment are: (1) determine and map surface minerals. rocks. and ices; (2) study the atmospheric dust composition. particle size, and spatial and temporal distribution; (3) investigate condensate clouds, CO2 and H2O, location. temperature, and height; (4) investigate polar cap deposits, e.g., growth, retreat, and energy balance; (5) measure the thermo-physical properties of surface materials; and (6) characterize the atmospheric structure and dynamics. The TES instrument is based upon a Michelson interferometer and collects data in the 1700-200 per cm region (about 6-50 micron at 5 or 10 per cm resolution. There are also broad-band bolometric (4.5100 microns and solar reflectance (0.3-2.7 microns) channels. The TES was designed to have a noise equivalent spectral radiance of 1.2 x l0(exp -8) per W per square cm per sr per cm corresponding to a signal-to-noise ratio of 490 at 1000 per cm (10 mm) for a 270 K scene and preflight data suggest a radiometric accuracy of about 1.2 x 10(exp -8) per W per square cm per sr per cm. In-flight observations indicate a small systematic calibration offset of about 1.2 x 10(exp -7) per W per square cm per sr per cm is present in the TES data. MGS achieved Mars orbital insertion September 11, 1997, and entered the initial aerobraking phase. MGS should have reached a circular orbit by early 1998. However, structural damage to one solar panel occurred during its deployment in the cruise phase and ultimately required an assessment of the extent of the damage and a much slower aerobraking period. This has delayed reaching the final circular orbit until March 1999. TES and the other MGS science instruments began operating just after orbital insertion and continued to obtain data until November 1998 when the TES was turned off to reduce power consumption on the spacecraft. TES data obtained during orbits 2 to 53 have previously been published and clearly illustrate the variety of scientific questions that can be addressed with them.

Roush, T. L.↗
NASA NTRS2019

Laboratory-Based Thermal Shock Investigation of Heat Flux Sensors for the Mars 2020 Backshell

In 2012 during the entry, descent, and landing of the Mars Science Laboratory (MSL), the MSL Entry, Descent, and Landing Instrumentation (MEDLI) sensor suite was collecting in-flight heatshield pressure and temperature data. The data collected by the MEDLI instruments has since been used for reconstruction of vehicle aerodynamics, atmospheric conditions, aerothermal heating, and Thermal Protection System (TPS) performance as well as material response model validation and refinement. The Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite for the Mars 2020 heatshield and backshell is being designed to expand on the measurements and knowledge gained from MEDLI. Similar to MEDLI, MEDLI2 will measure the pressure and temperature of the heatshield. MEDLI2 will additionally measure the temperature, pressure, total heat flux, and radiative heat flux on the backshell.Since the backshell instrumentation is new to MEDLI2, Do No Harm (DNH) testing was conducted on instrumented backshell TPS (SLA-561V) panels. The panels consisted of four pressure port holes, one Mars Entry Atmospheric Data System (MEADS) pressure port plug, one MEDLI2 Integrated Sensor Plug (MISP) thermal plug, and one heat flux sensor. DNH testing was conducted to ensure the performance of the TPS was not degraded due to sensor integration and to characterize any TPS performance changes. The testing consisted of environmental testing— vibration, shock, thermal vacuum (TVAC) cycling— and bounding aerothermal (arc jet) testing. During arc jet testing, the heat flux sensors embedded in the SLA-561V panels exhibited an unexpected temporary reduction in the heat flux sensor temperature and response. After review of the test results, it was determined that this unexpected response was confined to the two heat flux sensors that experienced the greatest thermal shock condition. This condition consisted of a liquid nitrogen (LN2) bath that induced temperatures of approximately -190°C, and then a transition (thermal shock) to an arc jet test at a heat rate of approximately 21 W/cm2. Both heat flux sensors that were exposed to this thermal shock experienced a blister in the thermal coating during the arc jet test.Two heat flux sensor thermal shock test series were performed to investigate the cause of the blistering and subsequent energy release. In these tests, the heat flux sensor was first cold soaked in either a dry ice or LN2 bath to induce temperatures of approximately -78°C or -190°C, respectively. Then the sensors were thermally shocked using two propane torches with a heat rate of either approximately 8 W/cm2 or 21 W/cm2. The key findings indicated that there is a correlation between thermal shock and the blistering observed in the DNH test series, and that the cause appeared to be rooted in the heat flux sensor epoxy that encapsulates the sensor thermopile.Since the heat flux sensors are required to measure heat fluxes up to 15 W/cm2 during the Mars 2020 entry, a third test series was designed to determine if blistering is an issue at this maximum expected flight heat flux. Results from all three thermal shock test series and a discussion about whether or not blistering of the heat flux sensor thermal coating could be an issue for the Mars 2020 mission will be presented.

Miller, R. A.↗
NASA NTRS1983

MIZEX-WEST NASA CV-990 flight report

As part of the Bering Sea marginal ice zone winter experiment (MIZEX-WEST), the CV-990 airborne laboratory was flown to assess the potential of using an extended range of wavelengths for improving passive microwave sea ice observations from spacecraft and second to provide an overview of the MIZ for large-scale processes studies. The aircraft was equipped with both imaging and fixed-beam, dual-polarized passive microwave radiometers ranging from 1.5 millimeter to 3 centimeter wavelengths. Visual, photographic, and thermal (10.7 micron) infrared surface observations were also made from the aircraft to complement the microwave measurements. The flight operations and in-flight observations are discussed and each flight is summarized including flight objective and instrument status. Preliminary mosaic images obtained with the ESMR imager, Nimbus-7 orbits over the Bering Sea, ice observations obtained by an ice observer on board, and composite maps of the general ice conditions for the month of February are also presented.

Cavalieri, D. J.↗
NASA NTRS1990

Debris/Ice/TPS Assessment and Photographic Analysis of Shuttle Mission STS-32R

A Debris Ice Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-32R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the external tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-32R, and their overall effect on the Space Shuttle program are documented.

Stevenson, Charles G.↗
NASA NTRS2003

Recent GSFC Space Power Systems Flight Experience

This viewgraph presentation provides information on the power supplies on scientific satellites, including batteries, and power supply anomalies during in-flight operations. The recent Goddard Space Flight Center (GSFC) missions profiled include the Tropical Rainfall Measuring Mission (TRMM), Landsat 7, Terra-EOS AM, Earth Observing Mission (EO1), Microwave Anistropy Probe (MAP), AQUA-EOS PM, and the Ice, Cloud and Land Elevation Satellite (ICESAT).

Enciso, Marlon L.↗
NASA NTRS2003

In-Flight Thermal Performance of the Geoscience Laser Altimeter System (GLAS) Instrument

The Geoscience Laser Altimeter System (GLAS) instrument is NASA Goddard Space Flight Center's first application of Loop Heat Pipe technology that provides selectable/stable temperature levels for the lasers and other electronics over a widely varying mission environment. GLAS was successfully launched as the sole science instrument aboard the Ice, Clouds, and Land Elevation Satellite (ICESat) from Vandenberg AFB at 4:45pm PST on January 12, 2003. After SC commissioning, the LHPs started easily and have provided selectable and stable temperatures for the lasers and other electronics. This paper discusses the thermal development background and testing, along with details of early flight thermal performance data.

Grob, Eric↗
NASA NTRS2005

Characterization of the Space Shuttle Ascent Debris using CFD Methods

After video analysis of space shuttle flight STS-107's ascent showed that an object shed from the bipod-ramp region impacted the left wing, a transport analysis was initiated to determine a credible flight path and impact velocity for the piece of debris. This debris transport analysis was performed both during orbit, and after the subsequent re-entry accident. The analysis provided an accurate prediction of the velocity a large piece of foam bipod ramp would have as it impacted the wing leading edge. This prediction was corroborated by video analysis and fully-coupled CFD/six degree of freedom (DOF) simulations. While the prediction of impact velocity was accurate enough to predict critical damage in this case, one of the recommendations of the Columbia Accident Investigation Board (CAIB) for return-to-flight (RTF) was to analyze the complete debris environment experienced by the shuttle stack on ascent. This includes categorizing all possible debris sources, their probable geometric and aerodynamic characteristics, and their potential for damage. This paper is chiefly concerned with predicting the aerodynamic characteristics of a variety of potential debris sources (insulating foam and cork, nose-cone ablator, ice, ...) for the shuttle ascent configuration using CFD methods. These aerodynamic characteristics are used in the debris transport analysis to predict flight path, impact velocity and angle, and provide statistical variation to perform risk analyses where appropriate. The debris aerodynamic characteristics are difficult to determine using traditional methods, such as static or dynamic test data, due to the scaling requirements of simulating a typical debris event. The use of CFD methods has been a critical element for building confidence in the accuracy of the debris transport code by bridging the gap between existing aerodynamic data and the dynamics of full-scale, in-flight events.

Murman, Scott M.↗
NASA NTRS2008

Marshall Space Flight Center's Impact Testing Facility Capabilities

Marshall Space Flight Center's (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960% then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California. The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility's unique capabilities were deemed a "National Asset" by the DoD. The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Relocated test equipment was dated and in need of upgrade. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. Future ITF improvements will be focused on continued instrumentation and performance enhancements. These enhancements will allow further, more in-depth, characterization of rain drop demise characterization and evaluation of ice crystal impact. Performance enhancements also include increasing the upper velocity limit of the current environmental guns to allow direct environmental simulation for missile components. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas grins, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Evans, Steve↗
NASA NTRS2008

Marshall Space Flight Center's Impact Testing Facility Capabilities

Marshall Space Flight Center's (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960s, then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California, The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility's unique capabilities were deemed a 'National Asset' by the DoD, The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Relocated test equipment was dated and in need of upgrade. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. Future ITF improvements will be focused on continued instrumentation and performance enhancements. These enhancements will allow further, more in-depth, characterization of rain drop demise characterization and evaluation of ice crystal impact. Performance enhancements also include increasing the upper velocity limit of the current environmental guns to allow direct environmental simulation for missile components. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas guns, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Evans, Steve↗
NASA NTRS2008

Marshall Space Flight Center's Impact Testing Facility Capabilities

Marshall Space Flight Center s (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960s, then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California. The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility s unique capabilities were deemed a "National Asset" by the DoD. The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas guns, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Finchum, Andy↗
NASA NTRS2012

Simulation Modeling Requirements for Loss-of-Control Accident Prevention of Turboprop Transport Aircraft

In-flight loss of control remains the leading contributor to aviation accident fatalities, with stall upsets being the leading causal factor. The February 12, 2009. Colgan Air, Inc., Continental Express flight 3407 accident outside Buffalo, New York, brought this issue to the forefront of public consciousness and resulted in recommendations from the National Transportation Safety Board to conduct training that incorporates stalls that are fully developed and develop simulator standards to support such training. In 2010, Congress responded to this accident with Public Law 11-216 (Section 208), which mandates full stall training for Part 121 flight operations. Efforts are currently in progress to develop recommendations on implementation of stall training for airline pilots. The International Committee on Aviation Training in Extended Envelopes (ICATEE) is currently defining simulator fidelity standards that will be necessary for effective stall training. These recommendations will apply to all civil transport aircraft including straight-wing turboprop aircraft. Government-funded research over the previous decade provides a strong foundation for stall/post-stall simulation for swept-wing, conventional tail jets to respond to this mandate, but turboprops present additional and unique modeling challenges. First among these challenges is the effect of power, which can provide enhanced flow attachment behind the propellers. Furthermore, turboprops tend to operate for longer periods in an environment more susceptible to ice. As a result, there have been a significant number of turboprop accidents as a result of the early (lower angle of attack) stalls in icing. The vulnerability of turboprop configurations to icing has led to studies on ice accumulation and the resulting effects on flight behavior. Piloted simulations of these effects have highlighted the important training needs for recognition and mitigation of icing effects, including the reduction of stall margins. This paper addresses simulation modeling requirements that are unique to turboprop transport aircraft and highlights the growing need for aerodynamic models suitable for stall training for these configurations. A review of prominent accidents that involved aerodynamic stall is used to illustrate various modeling features unique to turboprop configurations and the impact of stall behavior on susceptibility to loss of control that has led to new training requirements. This is followed by an overview of stability and control behavior of straight-wing turboprops, the related aerodynamic characteristics, and a summary of recent experimental studies on icing effects. In addition, differences in flight dynamics behavior between swept-wing jets and straight-wing turboprop configurations are discussed to compare and contrast modeling requirements. Specific recommendations for aerodynamic models along with further research needs and data measurements are also provided. 1

Crider, Dennis↗
NASA NTRS2011

Digital Calibration of TR Modules for Real-time Digital Beamforming SweepSAR Architectures

Real-time digital beamforming, combined with lightweight, large aperture reflectors, enable SweepSAR architectures such as that of the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI). These new instrument concepts require new methods for calibrating the multiple channels, which must be combined on-board, in real-time. The calibration of current state-of-the-art Electronically Steered Arrays typically involves pre-flight TR (Transmit/Receive) module characterization over temperature, and in-flight correction based on temperature, which ignores the effects of element aging and drifts unrelated to temperature. We are developing new methods for digitally calibrating digital beamforming arrays to reduce development time, risk and cost of precision calibrated TR modules for array architectures by accurately tracking modules' characteristics through closed-loop Digital Calibration, thus tracking systematic changes regardless of temperature. The benefit of this effort is that it would enable a new class of lightweight radar architecture, Digital Beamforming with SweepSAR, providing significantly larger swath coverage than conventional SAR architectures for solid earth and biomass remote sensing, while reducing mission mass and cost. This new instrument concept requires new methods for calibrating the multiple channels, which must be combined on-board, in real-time.

Real-time digital beamforming↗
NASA NTRS2012

Digital Calibration of TR Modules for Real-Tme Digital Beamforming SweepSAR Architectures

Real-time digital beamforming, combined with lightweight, large aperture reflectors, enable a new architecture, which is the baseline for the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI). This new instrument concept requires new methods for calibrating multiple simultaneous channels. The calibration of current state-of-the-art Electronically Steered Arrays typically involves pre-flight TR (Transmit/Receive) module characterization over temperature, and in-flight correction based on measured temperatures. This method ignores the effects of element aging and any drifts unrelated to temperature. We are developing new digital calibration of digital beamforming arrays, which helps to reduce development time, risk and cost. Precision calibrated TR modules enable real-time beamforming architectures by accurately tracking modules' characteristics through closed-loop digital calibration, which tracks systematic changes regardless of temperature. The benefit of this effort is that it would enable a new, lightweight radar architecture, with on-board digital beamforming. This provides significantly larger swath coverage than conventional SAR architectures

Hoffman, James Patrick↗
NASA NTRS2022

Controlling Triboelectrification Effects on Spacecraft Ethernet Cabling

Triboelectric charging of a spacecraft and launch vehicles on ascent may occur due to the process of contact and separation between the vehicle skin and aerosols, dust, ice, water droplets, smoke, and other particulates encountered in the flight path. Depending on characteristics at the atomic and molecular levels of the vehicle skin’s surface and the substances and particulates encountered, electrical charge will transfer between the vehicle and the encountered substances, resulting in an accumulation of electrical charge on the vehicle skin. If the vehicle skin is conductive and electrically bonded such that in its entirety it presents an equipotential surface, then the accumulated electrical charge will spread in a nearly uniform manner leaving all regions with a nearly equal potential with respect to each other and the surrounding environment. Regions that are not electrically bonded as described, or surfaces that have resistivity values, can reach different potentials than the surrounding surfaces. When this happens, the differing potentials may grow to very large magnitudes, leading to electrostatic discharge events between the regions. As the vehicle rises in altitude, the breakdown potential between these regions of differing potential decreases commensurate with decreases in atmospheric density and pressure. If the potential differences between surfaces of the vehicle become equal to or exceed the breakdown potential, one or more discharge events may occur, each of them generating voltage and current transients that can easily damage or interfere with the designed operation of on-board electrical, avionic, and communications and navigation systems. This lesson learned discusses an in-flight anomaly caused by triboelectric discharge events and exacerbated by the lack of adequate cable shielding that affected flight computer communication links. Also discussed are mitigations to prevent this occurrence.

Ethernet↗