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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 NTRS1979

Shuttle orbiter KU-band radar/communications system design evaluation

An expanded introduction is presented which addresses the in-depth nature of the tasks and indicates continuity of the reported effort and results with previous work and related contracts, and the two major modes of operation which exist in the Ku-band system, namely, the radar mode and the communication mode, are described. The Ku-band radar system is designed to search for a target in a designated or undesignated mode, then track the detected target, which might be cooperative (active) or passive, providing accurate, estimates of the target range, range rate, angle and angle rate to enable the orbiter to rendezvous with this target. The radar mode is described along with a summary of its predicted performance. The principal sub-unit that implements the radar function is the electronics assembly 2(EA-2). The relationship of EA-2 to the remainder of the Ku-band system is shown. A block diagram of EA-2 is presented including the main command and status signals between EA-2 and the other Ku-band units.

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NASA NTRS1976

Study to investigate and evaluate means of optimizing the radar function for the space shuttle

A detailed analysis of the spiral scan was performed for antenna sizes ranging from 20 inches to 36 inches in diameter and for search angles characteristic of both the radar and the communication acquisition modes. The power budgets for passive target radar detection were calculated for antenna diameters ranging from 20 to 36 inches. Dwell times commensurate with spiral scan were used for these budget calculations. The signal design for the candidate pulse Doppler system is summarized. Ground return analysis carried out for the passive target radar mode is examined, and the details are presented. A concluding description of the proposed candidate radar/communication system configuration is given.

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NASA NTRS2003

Airborne Radar Study of Mars Analogs in the Southwestern United States

The search for surface and near-surface liquid water on Mars is a central part of current and planned future exploration, which include radar sounders on Mars Express and MRO and proposed synthetic aperture radar (SAR) imagers. In order to penetrate sand and dust cover, these systems are proposed for longer wavelengths (e.g, from [2]: 24 cm / L-band and 74 cm / P-band) than those considered optimal for the detection of soil moisture (6 cm / C-band). However, there has been some success in detecting soil moisture at longer wavelengths. Given the size and mass constraints for Mars missions, the optimization of radar instrument parameters for meeting science objectives, such as searching for liquid water, is essential. In this on-going study, we are using repeat coverage of Mars analog sites with multifrequency (C, L and P band) airborne radar and ground truth soil sample data to assess the detectability of soil moisture.

Greeley, R.↗

NASA NTRS2017

Searching for Water Ice at the Lunar North Pole Using High-Resolution Images and Radar

Permanently shadowed regions (PSRs) at the lunar poles are potential reservoirs of frozen volatiles, and are therefore high-priority exploration targets. PSRs trap water and other volatiles because their annual maximum temperatures (40-100K) are lower than the sublimation temperatures of these species (i.e. H2O approx.104K). Previous studies using various remote sensing techniques have not been able to definitively characterize the distribution or abundance of ice in lunar PSRs. The purpose of this study is to search for signs of ice in PSRs using two complimentary remote sensing techniques: radar and visible images.

Mitchell, J. L.↗

NASA NTRS1977

Distress detection, location, and communications using advanced space technology

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

Sivertson, W. E., Jr.↗

NASA NTRS1977

Distress detection, location, and communications using advanced space technology

Sivertson, W. E., Jr.↗

NASA NTRS2004

Remote Sensing Capabilities to Detect Maritime Vessels in Distress

The National Aeronautics and Space Administration (NASA) has the responsibility for conducting research and development for search and rescue as charged under the National Search and Rescue Plan. For over two decades this task has been undertaken by the Search and Rescue Mission Office at the NASA Goddard Space Flight Center (GSFC). The technology used by the highly successful beacon locating satellite system, Cospas-Sarsat, was conceived and developed at GSFC and is managed by the National Oceanographic and Atmospheric Administration (NOAA). Using beacon-less remote sensing to find people and vessels in distress complements the demonstrated life saving capabilities of this satellite system. The Search and Rescue Mission Office has been investigating the use of fully polarimetric synthetic aperture radar to locate crashed aircraft. An overview of this effort and potential maritime applications of Search and Rescue Synthetic Aperture Radar (SAR) will be presented. The Mission Office has also developed a Laser search and rescue system called L-SAR. The prototype instrument was designed and built by SenSyTech Inc. It specifically targets the location of novel retro-reflective material easily applied to rescue equipment and vessels in distress. An overview of this effort will also be presented.

Larsen, Rudolph K.↗

NASA NTRS1995

Wind-Related Features and Processes on Venus Summary of Magellan Results

A search of Magellan synthetic aperture radar images covering about 98% of the venusian surface shows that aeolian features occur at all longitudes and latitudes. A global data base for wind streaks, the most common type of aeolian feature, was developed. For each of the 5970 streaks in the data base, information was compiled on location, streak type, radar backscatter, dimensions, azimuth, orientation with respect to local slope, and type of landform with which it is associated. In addition, streaks occurring in association with parabolic ejecta deposits were designated type P streaks, which constitute about 31% of the data base. Wind streak azimuths were analyzed to assess wind patterns at the time of their formation. Both hemispheres show strong westward and equatorward trends in azimuths, consistent with Hadley circulation and inferred upper atmospheric westward zonal winds. When type P streaks (those considered to result from transient impact events) were removed, the westward component was greatly reduced, suggesting that the upper zonal winds do not extend to the surface. The presence of equator-oriented streaks at high latitudes suggests that Hadley circulation extends to the poles. A field of possible yardangs found southwest of Mead Crater strikes NE-SW and occupies plains situated in a shallow topographic depression. Analysis of non-type P streaks in the area suggests that equatorward winds are funneled through the depression and are responsible for the erosion of the terrain to form the yardangs. Dune deposits are limited on Venus. Two dune fields were identified (Aglonice and Fortuna-Meshkenet) which total in area about 18,300 square km. Microdunes are proposed for some southern hemisphere areas which show distinctive radar reflectivities. Bragg scattering and/or subpixel reflections from the leeward faces of microdune bedforms could account for the unusual radar backscatter cross sections.

Greeley, Ronald↗

NASA NTRS1995

Wind-Related Features and Processes on Venus: Summary of Magellan Results

A search of Magellan synthetic aperture radar images covering approximately 98% of the venusian surface shows that aeolian features occur at all longitudes and latitudes. A global data base for wind streaks, the most common type of aeolian feature, was developed. For each of the 5970 streaks in the data base, information was compiled on location, streak type, radar backscatter, dimensions, azimuth, orientation with respect to local slope, and type of landform with which it is associated. In addition, streaks occurring in association with parabolic ejecta deposits were designated type P streaks, which constitute about 31% of the data base. Wind streak azimuths were analyzed to assess wind patterns at the time of their formation. Both hemispheres show strong westward and equatorward trends in azimuths, consistent with Hadley circulation and inferred upper atmospheric westward zonal winds. When type P streaks (those considered to result from transient impact events) were removed, the westward component was greatly reduced, suggesting that the upper zonal winds do not extend to the surface. The presence of equator-oriented streaks at high latitudes suggests that Hadley circulation extends to the poles. A field of possible yardangs found southwest of Mead Crater strikes NE-SW and occupies plains situated in a shallow topographic depression. Analysis of non-type P streaks in the area suggests that equatorward winds are funneled through the depression and are responsible for the erosion of the terrain to form the yardangs. Dune deposits are limited on Venus. Two dune fields were identified (Aglonice and Fortuna-Meshkenet) which total in area about 18,300 sq km. Microdunes are proposed for some southern hemisphere areas which show distinctive radar reflectivities. Bragg scattering and/or subpixel reflections from the leeward faces of microdune bedforms could account for the unusual radar backscatter cross sections.

Greeley, Ronald↗

NASA NTRS1993

Finding the Lost City

Nicholas Clapp, a filmmaker and archeology enthusiast, had accumulated extensive information concerning Ubar, the fabled lost city of ancient Arabia. When he was unable to identify its exact location, however, he turned to the Jet Propulsion Laboratory (JPL) for assistance in applying orbital remote sensing techniques. JPL scientists searched NASA's shuttle imaging radar, as well as Landsat and SPOT images and discovered ancient caravan tracks. This enabled them to prepare a map of the trails, which converged at a place known as Ash Shisr. An expedition was formed, which found structures and artifacts from a city that predates previous area civilization by a thousand years. Although it will take time to validate the city as Ubar, the discovery is a monumental archeological triumph.

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NASA NTRS1984

Ku-Band rendezvous radar performance computer simulation model

All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total software package developed on this program; and (3) development of radar cross section (RCS) computation models for three additional satellites. All changes in the tracking model involved improvements in the automatic gain control (AGC) and the radar signal strength (RSS) computer models. Although the search and acquisition computer models were developed under the auspices of the Hughes Aircraft Company Ku-Band Integrated Radar and Communications Subsystem program office, they have been supplied to NASA as part of the Ku-band radar performance comuter model package. Their purpose is to predict Ku-band acquisition performance for specific satellite targets on specific missions. The RCS models were developed for three satellites: the Long Duration Exposure Facility (LDEF) spacecraft, the Solar Maximum Mission (SMM) spacecraft, and the Space Telescopes.

Magnusson, H. G.↗

NASA NTRS1991

The Telecommunications and Data Acquisition Report

Posner, Edward C.↗

NASA NTRS1972

Project Cyclops: a Design Study of a System for Detecting Extraterrestrial Intelligent Life

The requirements in hardware, manpower, time and funding to conduct a realistic effort aimed at detecting the existence of extraterrestrial intelligent life are examined. The methods used are limited to present or near term future state-of-the-art techniques. Subjects discussed include: (1) possible methods of contact, (2) communication by electromagnetic waves, (3) antenna array and system facilities, (4) antenna elements, (5) signal processing, (6) search strategy, and (7) radio and radar astronomy.

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NASA NTRS1986

International Halley Watch: Discipline specialists for radio science

Some 34 radio observatories in 18 countries are participating in the Radio Science Net of the International Halley Watch. Approximately 100 radio astronomers are contributing to this effort, which has included observations of comets P/Crommelin and P/Giacobini-Zinner as well as P/Halley. It is clear that the record of data for the 18 cm OH ground state lambda doublet, which provides fundamental information on the gas production rate, kinematics, and potentially the magnetic field in the coma, will be vastly more complete and of higher accuracy than has even been obtained on any previous comet. The coverage by a number of radio observatories will enable short period variations to be studied and correlated with simultaneous data obtained at other wavelengths. Likewise, the first definitive detection of the important parent molecule hydrogen cyanide in a comet was obtained and is being studied by groups in the United States, Sweden, and France. The first detection of the comet with the Very Large Array telescope operated by NRAO was achieved and has produced exciting results for the distribution of emission at high angular resolution from the OH radical. At this writing data are still being obtained and being processed, and there are still strong indications that exciting information will be obtained from radar studies of P/Halley and from searches for additional parent molecules.

Irvine, W. M.↗

NASA NTRS1993

The Telecommunications and Data Acquisition Report

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC). The TDA Office also performs work funded by another NASA program office through and with the cooperation of OSC. This is the Orbital Debris Radar Program with tile Office of Space Systems Development. The TDA Office is directly involved in several tasks that directly support the Office of Space Science (OSS), with OSC funding DSN operational support. In radio science, The TDA Progress Report describes the spacecraft radio science program conducted using tile DSN. For the High-Resolution Microwave Survey (HRMS), the report covers implementation and operations for searching the microwave spectrum. In solar system radar, it reports on the uses of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets. In radio astronomy, the areas off support include spectroscopy, very long baseline interferometry, and astrometry.

Edward C Posner↗

NASA NTRS1975

A wide angle search technique for a 10.6 micron ladar

A ladar (laser radar) sensor designed around a pulsed passively Q-switched CO2 laser, capable of a efficient and rapid scans with a narrow beam over a wide field of view, is considered for surveillance and tracking applications in space. The output is a train of narrow pulses with a controllable pulse repetition rate. A resonant vibrating mirror in back of a classical Gregorian telescope, and a plane pointing mirror in front for beam steering, are used in scanning. Scan pulse sequences are described and illustrated. The 10.6 micron ladar set is under consideration as baseline sensor for various space rendezvous and docking applications.

Levinson, S.↗

NASA NTRS1992

The Telecommunications and Data Acquisition Report

Archival reports on developments in programs managed by the Jet Propulsion Laboratory's (JPL's) Office of Telecommunications and Data Acquisition (TDA) are published in the TDA Progress Report. In the search for extraterrestrial intelligence (SETI), the TDA Progress Report reports on implementation and operations for searching the microwave spectrum. In solar system radar, it reports on the uses of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets. In radio astronomy, the areas of support include spectroscopy, very long baseline interferometry, and astrometry. These three programs are performed for NASA's Office of Space Science and Applications (OSSA), with the Office of Space Operations funding DSN operational support.

Posner, Edward C.↗

NASA NTRS2003

On the Determination of Local Sites for Shallow Ground Water Prospection Using Low Frequency Sounding Radars on Mars

Low frequency sounding radars should be able to probe the Martian subsurface layers down to varying depths, depending on the geo-electrical properties of the sounded sites. We present in this work four frequency dependent geo-electrical models of the Martian subsurface in the 1-20 MHz frequency band, based on laboratory electromagnetic characterization of Martian soil analogues. Those models correspond to local Martian sites, where we considered particular interest for the search of water using mainly the Ground Penetrating Radar (GPR) instrument of the Netlander mission. Results and discussion are also valid for both sounding experiments MARSIS and SHARAD. The four models of the Martian subsurface are designed to represent terrains where recent fluvial like features suggest the presence of near subsurface ground ice and probably liquid water. We performed measurements on volcanic and sedimentary materials that may be present on these sites under the appropriate geophysical conditions that may exist in those terrains. We then simulated the backscattered radar echo arising from each site in the 2 MHz frequency band, using the Finite Difference Time Domain (FDTD) algorithm, in order to evaluate the instrument performances to probe the subsurface stratigraphy of each site. Our results confirm that the near subsurface rich iron oxide mineralogy controls the instrument performances in terms of penetration depth and signal to noise ratio in the 2 MHz frequency band. We also discuss the geophysical and geo-electrical sounding conditions that could lead to an ambiguous detection of shallow subsurface water on Mars for the Netlander GPR. Finally we hope to present by the conference time a terrestrial test analogue site selected according to those creteria where deep sub-surface water have been detected 600 m deep using a prototype of the 2 MHz Netlander GPR in a field survey performed last febrary in the eastern part of the Egyptian desert.

Heggy, E.↗