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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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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Wireless Acoustic Measurement System

A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in "Predicting Rocket or Jet Noise in Real Time" (SSC-00215-1), which appears elsewhere in this issue of NASA Tech Briefs. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro-ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that provides an intuitive graphical user interface through which an operator at the control server can control the operations of the field stations for calibration and for recording of measurement data. A test engineer positions and activates the WAMS. The WAMS automatically establishes the wireless network. Next, the engineer performs pretest calibrations. Then the engineer executes the test and measurement procedures. After the test, the raw measurement files are copied and transferred, through the wireless network, to a hard disk in the control server. Subsequently, the data are processed into 1/3-octave spectrograms.

Anderson, Paul D.↗
NASA NTRS2004

Lightweight, Flexible, Thin, Integrated Solar-Power Packs

Lightweight, flexible, thin, one-piece, solar-power packs are undergoing development. Each power pack of this type is a complete, modular, integrated power-supply system comprising three power subsystems that, in conventional practice, have been constructed as separate units and connected to each other by wires. These power packs are amenable to a variety of uses: For example, they could be laminated to the tops of tents and other shelters to provide or augment power for portable electronic equipment in the field, and they could be used as power sources for such small portable electronic systems as radio transceivers (including data relays and cellular telephones), laptop computers, video camcorders, and Global Positioning System receivers.

Hanson, Robert R.↗
NASA NTRS2020

SMARt-STEReO: Preliminary Model Description

Wildfires have increasingly become major threat to US towns and cities, with California alone having its most destructive wildfire seasons to date in 2017 and 2018 and 2020 already becoming one of the worst fire years on record, causing the large-scale evacuations, the destruction of towns and property, and a significant release of hazardous smoke over the entire west coast. Thus, the U.S. Forest Service recently spent over 50% of its budget on wildfire management – funds which could otherwise be directed to science that could support fire prevention. Aerial support plays a major role in fighting wildfires. Airtankers, helicopters, and other aerial assets support the construction of fire-lines, gather data, and transport crews and equipment. However, presently, aerial firefighting operations rely on relatively unsophisticated technologies for communications, such as over-the-air radios, which limit the ability of pilots and management to relay fire data and coordinate operations. Aerial operations in and around fires are additionally high-risk activities due to the variable, dangerous conditions and complex, technically difficult maneuvers which must be performed to, for example, conduct a retardant drop. Thus, between 2000 and 2013, of the 298 wildland firefighter fatalities, 26% were related to aerial operations. As a result, there is significant potential to both improve the performance and resiliency of wildfire response while reducing risk to human operators.

Daniel E Hulse↗
NASA NTRS2018

Radio Science System Design and Measurement Results for the NASA Deep Space Network (DSN)

Radio science measurements have been performed using the NASA Deep Space Network (DSN) with many different spacecraft over several decades. Radio science has been used for the study of planetary atmospheres, the solar corona and the search for gravity waves, among other things. The majority of these measurements are made using the X and Ka-band deep space bands. Although the primary mission for the DSN is tracking, telemetry and command (TT&C) for NASA’s many deep-space spacecraft, radio science measurements continue to be an important secondary mission. The science requirements for these measurements have resulted in stringent performance requirements for both the spacecraft and ground system equipment. In particular, the requirements for amplitude stability, phase stability (Allen deviation) and phase noise are very demanding. The system Allen deviation requirement at Ka-band is < 2.4 E-15 over 1000 seconds, while the phase noise requirement is < -50 dBc/Hz for a 1 Hz offset. Various design techniques have been used for the DSN radio frequency (RF) electronics, high power transmitters and antenna structures to meet the stringent requirements for all 3 of these parameters. Some details for the design techniques will be described in the paper. Another important consideration for a radio science system is the verification approach for components, as well as for individual subsystems and then the overall system. Phase-locked oscillators (PLOs) are one of the key component types that determine overall phase noise and Allen deviation system performance. Measurement techniques used for PLOs, as well as for the overall ground system, will be discussed. Measurement results for the 2 new DSN antennas, recently built under the DSN Aperture Enhancement Project (DAEP) will also be shown. In addition, some recent radio science measurements from the Cassini and JUNO missions, using the new antennas, will be presented.

LaBelle, Remi C.↗
NASA NTRS1980

Hectometer and kilometer solar observations

Three dimensional 'snapshots' of the large scale solar magnetic field topology as well as the solar wind electron density distribution from about 0.1 to 1 AU are obtained by tracking traveling solar radio bursts at the hectometer and kilometer wavelengths with instruments aboard the ISEE-3 satellite and the HELIOS-2 solar probe. Both instruments observe in the frequency range from 30 kHz to a 1 MHz and both are equipped with dipole antennas located in the vehicle spin plane. ISEE-3 also has a dipole along the spin axis and the signals from the two ISEE-3 antennas are combined to give the aximuth and elevation angles of the radio source. Triangulation between HELIOS-2 and ISEE-3 provides the additional observation necessary to determine uniquely the position of the radio source in space at each observing frequency.

Stone, R. G.↗
NASA NTRS1996

Standardized, Low Cost Communications for Planetary Mission

For Deep Space Missions, the Radio-Frequency (RF) communications link provides both communications and navigation services. In this article we discuss the increased efficiency and reduced cost that can result from the potential consolidation of the two services into one suite of equipment, and the utilization of guaranteed delivery standard protocols to improve the communications service.

Deep↗
NASA NTRS1974

Radio-controlled, sound-operated switch

Switch presently provides remote control switching, by radio signals, or pollution sampling devices. Can be used for remote weather station interrogation, firing of pyrotechnics, control of dangerous equipment, or control of device in location where it is impractical to run metallic conductors because of time limitations, distance, or terrain.

Bryant, T. D.↗
NASA NTRS1977

CCIR papers on telecommunications for deep space research

A brief description is given of United States participation in the process of developing the technical basis for international allocation and regulation of the radio frequency spectrum. The telecommunication requirements for deep space research are considered. Topics include functional requirements, methods and techniques, and equipment characteristics.

Degroot, N. F.↗
NASA NTRS2020

On-Orbit Validation of a Framework for Spacecraft-Initiated Communication Service Requests with NASA's SCaN Testbed

We design, analyze, and experimentally validate a framework for demand-based allocation of high-performance space communication service in which the user spacecraft itself initiates a request for service. Leveraging machine-to-machine communications, the automated process has potential to improve the responsiveness and efficiency of space network operations. We propose an augmented ground station architecture in which a hemispherical-pattern antenna allows for reception of service requests sent from any user spacecraft within view. A suite of ground-based automation software acts upon these direct-to-Earth requests and allocates access to high-performance service through a ground station or relay satellite in response to immediate user demand. A software-defined radio transceiver, optimized for reception of weak signals from the helical antenna, is presented. Design and testing of signal processing equipment and a software framework to handle service requests is discussed. Preliminary results from on-orbit demonstrations with a testbed onboard the International Space Station are presented to verify feasibility of the concept.

Adam M Gannon↗
DOE OSTI2023

Distributed Power Allocation for 6-GHz Unlicensed Spectrum Sharing via Multi-agent Deep Reinforcement Learning

We consider the problem of power allocation over the 6 GHz Unlicensed National Information Infrastructure (UNII)- 5 spectrum. We propose a novel deep Reinforcement Learning (DRL)-based distributed power allocation scheme which utilizes the multi-agent Deep Deterministic Policy Gradient (MADDPG) algorithm. In particular, we model the base stations (BSs) as DRL agents that simultaneously determine the transmit powers to their scheduled user equipment (UE) in a synchronized manner. The power decision of each BS is based on its own observation of the radio environment, which consists of several local interference measurements and a limited amount of information obtained from other BSs. One advantage of the proposed scheme is that it addresses the single-agent non-stationarity problem of RL in the multi-agent scenario by incorporating the actions and observations of other BSs into each BS’s own critic which helps it to gain a more accurate perception of the overall radio environment. A centralized-training-distributed execution framework is used to train the policies where the critics are trained over the joint actions and observations of all BSs while the actor of each BS only takes the local observation as input in order to produce the transmit power. Simulation shows that the proposed power allocation scheme can achieve better throughput performance than several state-of-the-art approaches.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1978

DSN radio science system, Mark III-78

Mark III-78, is one of eight DSN Data Systems which provide major data types and functional capabilities to flight projects. It includes the equipment, software, personnel, documentation, procedures, and resources necessary to deliver the required data to flight projects. A system definition is given along with key characteristics, functional description, system configuration, testing, implementation status, and system schedule.

Berman, A. L.↗
NASA NTRS1981

Possibility of a new approach to processing space pulse radio signals

A approach to the processing of space pulse radio signals, which makes it possible to achieve a high level of time resolution is proposed. The approach is based on the utilization of the Fourier transform of a radio pulse envelope in the interstellar medium effect. The conditions of applicability of the proposed method and the requirements for recording equipment are substantiated. Also indicated is the possibility of obtaining superresolution with the utilization of the given method of signal processing.

Bocharov, A. A.↗
NASA NTRS1995

STS-64 Space Shuttle mission report

The STS-64 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Redesigned Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the sixty-fourth flight of the Space Shuttle Program and the nineteenth flight of the Orbiter vehicle Discovery (OV-103). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-66; three SSMEs that were designated as serial numbers 2031, 2109, and 2029 in positions 1, 2, and 3, respectively; and two SRB's that were designated Bl-068. The RSRM's that were installed in each SRB were designated as 360L041 A for the left SRB, and 360L041 B for the right SRB. The primary objective of this flight was to successfully perform the planned operations of the Lidar In-Space Technology Experiment (LITE), and to deploy the Shuttle Pointed Autonomous Research Tool for Astronomy (SPARTAN) -201 payload. The secondary objectives were to perform the planned activities of the Robot Operated Materials Processing System (ROMPS), the Shuttle Amateur Radio Experiment - 2 (SAREX-2), the Solid Surface Combustion Experiment (SSCE), the Biological Research in Canisters (BRIC) experiment, the Radiation Monitoring Equipment-3 (RME-3) payload, the Military Application of Ship Tracks (MAST) experiment, and the Air Force Maui Optical Site Calibration Test (AMOS) payload.

Fricke, Robert W., Jr.↗
NASA NTRS1998

STS-88 Day 08 Highlights

On this eighth day of the STS-88 mission, the flight crew, Commander Robert D. Cabana, Pilot Frederick W. Sturckow, and Mission Specialists Nancy J. Currie, James H. Newman, Jerry L. Ross, and Sergei Krikalev enter the International Space Station where Krikalev and Currie install a new battery charging unit. Sturckow and Currie remove launch restraint bolts from some of the panels inside Zarya. Cabana, Ross, and Newman check the communications system's videoconferencing capability. Then Ross, Newman, and Krikalev transfer equipment and supplies from Endeavour for future inhabitants of the Space Station. The crew then participates in an interview with KNX Radio in Los Angeles and KARE-TV in Minneapolis, Minnesota.

Source record↗
NASA NTRS2007

A New Source of Space Weather Data

The twin STEREO spacecraft were launched on October 26,2006 and, after spending several weeks in alignment orbits, became operational in heliocentric orbits on January 2 1,2007. The spacecraft are now in orbits similar to Earth's and are separating from each other at a rate of about 45 degrees per year as viewed from the sun. The STEREO spacecraft are each equipped with a complement of EUV, and white light imagers as well as particles and fields in situ instruments and a radio burst tracker. In addition to full resolution data downloaded once per day, each spacecraft broadcasts a real time telemetry 'beacon' stream containing compressed images and typically one minute averages of solar wind measurements and radio intensities. These real time data streams are received by a mix of NOAA and NASA-managed tracking stations and the data is transmitted by these stations to the STEREO Science Center at NASA Goddard Space Flight Center where they are processed into useable parameters with a latency of less than five minutes from receipt. As the two spacecraft recede from the sun-Earth line, triangulation of the imaging and radio measurements should allow better estimate of the speed and direction of coronal mass ejections, allowing a more precise estimate of their arrival at Earth. In situ particles and fields measurements, particularly for the spacecraft (Behind) trailing Earth in its orbit, will sample the solar wind that will eventually co-rotate around to the sun-Earth line. Late in the prime mission when the spacecraft are very far (>90 degrees) from the sun-Earth line, observations from the Behind spacecraft, will be particularly valuable for providing a preview of active regions well beyond the sun's East limb (as seen from Earth). Continually updated STEREO space weather data can be viewed and downloaded at http:/lstereo-ssc.nascom.nasa.govldata/beacon/.

Kaiser, Michael L.↗
NASA NTRS2007

MMIC Amplifiers for 90 to 130 GHz

This brief describes two monolithic microwave integrated-circuit (MMIC) amplifier chips optimized to function in the frequency range of 90 to 130 GHz, covering nearly all of F-band (90 - 140 GHz). These amplifiers were designed specifically for local-oscillator units in astronomical radio telescopes such as the Atacama Large Millimeter Array (ALMA). They could also be readily adapted for use in electronic test equipment, automotive radar systems, and communications systems that operate between 90 and 130 GHz.

Samoska, Lorene↗
NASA NTRS2010

The AuScope Project and Trans-Tasman VLBI

Three 12-meter radio telescopes are being built in Australia (the AuScope project) and one in New Zealand. These facilities will be fully-equipped for undertaking S and X-band geodetic VLBI observations and correlation will take place on a software correlator (part of the AuScope project). All sites are equipped with permanent GPS receivers to provide co-location of several space geodetic techniques. The following scientific tasks of geodesy and astrometry are considered. 1. Improvement and densification of the International Celestial Reference Frame in the southern hemisphere; 2. Improvement of the International Terrestrial Reference Frame in the region; 3. Measurement of intraplate deformation of the Australian tectonic plate.

Lovell, Jim↗
NASA NTRS2018

Initial Operations Experience and Results from the Juno Gravity Experiment

Radio communications between the Juno spacecraft, in orbit around Jupiter, and the Earth-based observing stations of NASA’s Deep Space Network enable measurements of the Doppler shift induced on the radio signals by Juno’s motion in the Jovian environment. This measurement of the Doppler shift improves the knowledge of Jupiter’s gravitational field. As a radio science instrument, Juno’s gravity science instrument utilizes a ground component at the Deep Space Network’s DSS-25 antenna, equipped with simultaneous dual X- and Ka-band transmitters and receivers, and a spacecraft component, which includes X- and Ka-band transponders to relay the transmitted signal back to Earth. Originally planned to be in 14-day orbits around Jupiter, a risk identified in the propulsion system led to the decision to stay in the 53-day orbit period. Rapid turnaround of observation planning led to successful near-term perijove passes. Although maintaining a 53-day orbit period provides a scientific benefit to the gravity science investigation, the longer orbit period further increases the large dynamic range in Doppler shift and pointing angles induced by the geometry of each perijove. Between entering orbit at Jupiter on July 5, 2016 and September 2017, the Juno spacecraft has executed eight closest approach periods every 53 days where science data was collected. The first five perijove passes were conducted in different telecom configurations, each presenting unique challenges in data collection and processing. Perijoves PJ-01, PJ-02, PJ-03, and PJ-06 utilized the high-gain antenna and various configurations of the X- and Ka-bands. Perijoves PJ-04 and PJ-05 utilized the medium-gain antenna at X-band only while the spacecraft was off-Earth point. Additional perijoves are planned every 53-days, with an additional five by March 2018. Lessons learned from operating and collecting data at each perijove are documented and will be utilized in future perijoves. Analysis of the first two gravity science perijoves has improved the precision of Jupiter’s gravity field by a factor of five, providing crucial constraints on the interior structure of Jupiter.

Buccino, Dustin↗