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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Navigation for IUS deployment. TDRSS navigation accuracy in support of IUS deployment, phase 1

The navigation accuracy for tracking the orbiter prior to interim upper stage (IUS) deployment using the tracking data relay satellite system (TDRSS) was studied. The orbiter navigation accuracy for both one and two TDRSS satellites, for short and long data arcs, and for Doppler-only and Doppler-plus range solutions was examined. All test cases were run with the orbiter in a 150-n. mi. circular orbit, 28.5 degree inclination, at the time interval from the completion of the orbital maneuvering system (OMS)-2 maneuver to OMS-2 plus 2 hours (approximate time for IUS deployment). The data used were simulated by the simulation navigation (SIMNAV) program. The software tool used to process the TDRS data was the Shuttle Navigation Analysis Program (SNAP), a Kalman filter tool used to solve for the orbiter position and velocity. Results summarize the expected navigation accuracy using the TDRS system. It was concluded that: (1) data from both TDRS satellites were essential for accurate navigation results: (2) range data were essential for the short arc test case but were not needed for the long arc test case; and (3) with Doppler and range data from both TDRS satellites, the results converged to a reasonable solution after 5 to 10 minutes of data.

Wylie, A. D.↗
NASA NTRS1978

Subcarrier phase recovery performance in bent-pipe mode of Shuttle data transmission

The subcarrier phase recovery is analyzed for the bent-pipe mode of Space Shuttle detached-payload data transmission on the Tracking and Data Relay Satellite System (TDRSS) Ku-band return link. The high-power component of the subcarrier modulation is unrestored payload data, either at baseband or modulating another subcarrier. At the receiver a Costas loop recovers the subcarrier phase. To analyze its performance in the baseband case, we obtain the loop S-curve, the power spectral density of the equivalent noise process, and the loop phase error variance.

Mckenzie, T. M.↗
NASA NTRS1981

Ground-to-ground communications for mission support

The objective of the NASA Communications Division is to provide operational communications in support of NASA projects and mission activities. Nascom is a generic term referring collectively to a global system of circuits and switching and terminal facilities established and operated by NASA to provide longhaul operational communications support for all NASA projects. Aspects of network evolution are discussed, taking into account the integrated Nascom network. A description is presented of the present Nascom network, giving attention to the Spaceflight Tracking and Data Network (STDN), the Deep Space Network (DSN), the voice network, and the Teletypewriter (TTY) Network. Concepts and techniques for the 1980's are also considered. It is pointed out that the Nascom Network will extend the Tracking and Data Relay Satellite System (TDRSS) forward- and return-link services to users of the TDRSS by providing ground-to-ground data communications links between the NASA Ground Terminal at White Sands, New Mexico, and major user spacecraft control centers and data capture/data processing facilities.

Dickinson, W. B.↗
NASA NTRS2011

Simultaneous Ka-Band Site Characterization: Goldstone, CA, White Sands, NM, and Guam, USA

To statistically characterize atmospheric effects on Ka-band links at NASA operational sites, NASA has constructed site test interferometers (STI s) which directly measure the tropospheric phase stability and rain attenuation. These instruments observe an unmodulated beacon signal broadcast from a geostationary satellite (e.g., Anik F2) and measure the phase difference between the signals received by the two antennas and its signal attenuation. Three STI s have been deployed so far: the first one at the NASA Deep Space Network Tracking Complex in Goldstone, California (May 2007); the second at the NASA White Sands Complex, in Las Cruses, New Mexico (February 2009); and the third at the NASA Tracking and Data Relay Satellite (TDRS) Remote Ground Terminal (GRGT) complex in Guam (May 2010). Two station-years of simultaneous atmospheric phase fluctuation data have been collected at Goldstone and White Sands, while one year of data has been collected in Guam. With identical instruments operating simultaneously, we can directly compare the phase stability and rain attenuation at the three sites. Phase stability is analyzed statistically in terms of the root-mean-square (rms) of the tropospheric induced time delay fluctuations over 10 minute blocks. For two years, the time delay fluctuations at the DSN site in Goldstone, CA, have been better than 2.5 picoseconds (ps) for 90% of the time (with reference to zenith), meanwhile at the White Sands, New Mexico site, the time delay fluctuations have been better than 2.2 ps with reference to zenith) for 90% of time. For Guam, the time delay fluctuations have been better than 12 ps (reference to zenith) at 90% of the time, the higher fluctuations are as expected from a high humidity tropical rain zone. This type of data analysis, as well as many other site quality characteristics (e.g., rain attenuation, infrastructure, etc.) will be used to determine the suitability of all the sites for NASA s future communication services at Ka-band.

Acosta, Roberto↗
NASA NTRS2019

Seeker 1.0: Prototype Robotic Free Flying Inspector Mission Overview

Seeker 1.0 is a prototype free flying robot that will one day be capable of inspecting human-rated spacecraft. Building off previous free flyer experience, this technology will eventually improve safety of human spacecraft by offering a variety of inspection capabilities for both routine and emergency scenarios providing increased capability and safety over current inspection methods. Seeker 1.0 is capable of 6 degree of freedom flight via a cold gas propulsion system and can operate up to 1 hour via a semi-autonomous guidance, navigation, and control system. The prototype spacecraft is capable of capturing still images at a variety of resolutions up to 13 MP. The initial test flight utilizes a command and data relay box called Kenobi. Kenobi is a derivative of the Seeker design and will communicate between Cygnus and Seeker and store data for post-mission downlink. Seeker and Kenobi have launched inside a NanoRacks External CubeSat Deployer (NRCSD-E) attached to the NG-11 Cygnus ISS resupply vehicle and will operate after Cygnus departs ISS and moves to a safe altitude. Operations will last approximately 30 minutes and will consist of basic vehicle maneuvers while capturing high-resolution still images. With any remaining time and propellant, Seeker will demonstrate additional safety capabilities and maneuvers required for operations around a crewed spacecraft. The Seeker project utilized the Class IE process that allows for streamlined flight hardware development and increased mission risk tolerance.

Spacecraft Inspection↗
NASA NTRS1978

A review of satellite time-transfer technology: Accomplishments and future applications

The research accomplishments by NASA in meeting the needs of the space program for precise time in satellite tracking are presented. As a major user of precise time signals for clock synchronization of NASA's worldwide satellite tracking networks, the agency provides much of the necessary impetus for the development of stable frequency sources and time synchronization technology. The precision time required for both satellite tracking and space science experiments has increased at a rate of about one order of magnitude per decade from 1 millisecond in the 1950's to 100 microseconds during the Apollo era in the 1960's to 10 microseconds in the 1970's. For the Tracking and Data Relay Satellite System, satellite timing requirements will be extended to 1 microsecond and below. These requirements are needed for spacecraft autonomy and data packeting.

Cooper, R. S.↗
NASA NTRS1980

Networks consolidation program

The Networks Consolidation Program (NCP) goals were defined to include the planning, designing, and implementing of a single network of ground tracking stations. The proposed consolidated network is to make use of facilities that are now included in the Goddard Ground Spaceflight Tracking and Data Network as well as the existing JPL Deep Space Network. These facilities are to be combined and modified to provide a consolidated network capable of supporting the set of planetary and Highly Elliptical Earth Orbiter missions that are planned for the Tracking and Data Relay Satellite System era. The history of activities and events that led to the decision to consolidate the NASA ground tracking and data networks are traced. A summary of the management and planning activities that have taken place at the Jet Propulsion Laboratory, Goddard Space Flight Center, and at the NASA Headquarters Office of Space Tracking and Data Systems, with respect to the NCP, from the time of decision in October 1979 to the present, are discussed.

Yeater, M. L.↗
NASA NTRS1983

The NASA data systems standardization program - Radio frequency and modulation

The modifications being considered by the NASA-ESA Working Group (NEWG) for space-data-systems standardization to maximize the commonality of the NASA and ESA RF and modulation systems linking spaceborne scientific experiments with ground stations are summarized. The first phase of the NEWG project shows that the NASA MK-IVA Deep Space Network and Shuttle Interrogator (SI) systems in place or planned for 1985 are generally compatible with the ESA Network, but that communications involving the Tracking and Data Relay Satellite (TDRS) are incompatible due to its use of spread-spectrum modulation, pseudonoise ranging, multiple-access channels, and Mbit/s data rates. Topics under study for the post-1985 period include low-bit-rate capability for the ESA Network, an optional 8-kHz command subcarrier for the SI, fixing the spacecraft-transponder frequency-multiplication ratios for possible X-band uplinks or X-band nondeep-space downlinks, review of incompatible TDRS features, and development of the 32-GHz band.

Martin, W. L.↗
NASA NTRS1989

Image processing using Gallium Arsenide (GaAs) technology

The need to increase the information return from space-borne imaging systems has increased in the past decade. The use of multi-spectral data has resulted in the need for finer spatial resolution and greater spectral coverage. Onboard signal processing will be necessary in order to utilize the available Tracking and Data Relay Satellite System (TDRSS) communication channel at high efficiency. A generally recognized approach to the increased efficiency of channel usage is through data compression techniques. The compression technique implemented is a differential pulse code modulation (DPCM) scheme with a non-uniform quantizer. The need to advance the state-of-the-art of onboard processing was recognized and a GaAs integrated circuit technology was chosen. An Adaptive Programmable Processor (APP) chip set was developed which is based on an 8-bit slice general processor. The reason for choosing the compression technique for the Multi-spectral Linear Array (MLA) instrument is described. Also a description is given of the GaAs integrated circuit chip set which will demonstrate that data compression can be performed onboard in real time at data rate in the order of 500 Mb/s.

Miller, Warner H.↗
NASA NTRS1993

EOS ground data systems: A description and interface overview

The Earth Observing System (EOS) is planned as a space-based measurement system, earth-science research program, and data and information system (EOSDIS). It will consist of several high data rate spacecraft with multiple earth sensing instruments which provide investigators with a thorough, longterm view of the earth's environment. Up to seven spacecraft may be supported at once, either in operational, checkout, or testing phases; and the average data rate from the EOS satellites in orbit at any one time is expected to be from 18 to 60 Mbps. Providing the data processing and flight operations support for EOS will be the EOSDIS Core System (ECS). The ECS will command and control the spacecraft; process and store the EOS data; provide access to the data for years; and support researchers. The data processing aspects of the ECS consist of a collection of Distributed Active Archive Centers (DAAC's) which perform the product generation, data archive and distribution, and information management services. Flight operations aspects will be provided by the EOS Operations Center, by instrument control centers, and by widely distributed instrument support terminals. The communications and system management aspects will be provided by the EOSDIS Science Network and the System Management Center. In addition to the EOS satellite data, other data sets from earlier earth science missions are also to be added to designated DAAC's. Other ground data systems which will provide support to EOS for acquiring, transporting, processing, and distributing the transformed spacecraft data are currently being defined or are being upgraded for the EOS era. These systems include the Space Network consisting of the Tracking and Data Relay Satellite System (TDRSS), the TDRSS Ground Terminals, and the Network Control Center as well as the night Dynamics Facility, the EOS Data and Operations System, and EOS Communications. This paper briefly describes data handling by the ECS, the support data systems, their interfaces, and their roles.

Smith, Gene↗
NASA NTRS2002

Demonstrating Acquisition of Real-Time Thermal Data Over Fires Utilizing UAVs

A disaster mitigation demonstration, designed to integrate remote-piloted aerial platforms, a thermal infrared imaging payload, over-the-horizon (OTH) data telemetry and advanced image geo-rectification technologies was initiated in 2001. Project FiRE incorporates the use of a remotely piloted Uninhabited Aerial Vehicle (UAV), thermal imagery, and over-the-horizon satellite data telemetry to provide geo-corrected data over a controlled burn, to a fire management community in near real-time. The experiment demonstrated the use of a thermal multi-spectral scanner, integrated on a large payload capacity UAV, distributing data over-the-horizon via satellite communication telemetry equipment, and precision geo-rectification of the resultant data on the ground for data distribution to the Internet. The use of the UAV allowed remote-piloted flight (thereby reducing the potential for loss of human life during hazardous missions), and the ability to "finger and stare" over the fire for extended periods of time (beyond the capabilities of human-pilot endurance). Improved bit-rate capacity telemetry capabilities increased the amount, structure, and information content of the image data relayed to the ground. The integration of precision navigation instrumentation allowed improved accuracies in geo-rectification of the resultant imagery, easing data ingestion and overlay in a GIS framework. We focus on these technological advances and demonstrate how these emerging technologies can be readily integrated to support disaster mitigation and monitoring strategies regionally and nationally.

Ambrosia, Vincent G.↗
NASA NTRS1985

Ku band - The first year of operation

The Space Shuttle Orbiter's Ku-band integrated radar and communications system furnishes the preferred link through the Tracking and Data Relay Satellite (TRDS), providing rendezvous radar function. During the first year of operations, communications through TRDS provided a channel for the 48 Mbps data from Spacelab. Attention is presently given to the most significant activities of the radar during its initial year.

Griffin, J. W.↗
NASA NTRS1991

Data distribution satellite

A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs.

Price, Kent M.↗
NASA NTRS1994

Production and quality assurance automation in the Goddard Space Flight Center Flight Dynamics Facility

The Flight Dynamics Facility (FDF) at the NASA Goddard Space Flight Center (GSFC) generates numerous products for NASA-supported spacecraft, including the Tracking and Data Relay Satellites (TDRS's), the Hubble Space Telescope (HST), the Extreme Ultraviolet Explorer (EUVE), and the space shuttle. These products include orbit determination data, acquisition data, event scheduling data, and attitude data. In most cases, product generation involves repetitive execution of many programs. The increasing number of missions supported by the FDF has necessitated the use of automated systems to schedule, execute, and quality assure these products. This automation allows the delivery of accurate products in a timely and cost-efficient manner. To be effective, these systems must automate as many repetitive operations as possible and must be flexible enough to meet changing support requirements. The FDF Orbit Determination Task (ODT) has implemented several systems that automate product generation and quality assurance (QA). These systems include the Orbit Production Automation System (OPAS), the New Enhanced Operations Log (NEOLOG), and the Quality Assurance Automation Software (QA Tool). Implementation of these systems has resulted in a significant reduction in required manpower, elimination of shift work and most weekend support, and improved support quality, while incurring minimal development cost. This paper will present an overview of the concepts used and experiences gained from the implementation of these automation systems.

Chapman, K. B.↗
NASA NTRS2002

On-Orbit Performance Verification and End-To-End Characterization of the TDRS-H Ka-band Communications Payload

In June 2000, NASA launched the first of three next generation Tracking and Data Relay Satellites (TDRS-H) equipped with a Ka-band forward and return service capability. This Ka-band service supports forward data rates of up to 25 Mb/sec using the 22.55-23.55 GHz space-to-space allocation. Return services are supported via channel bandwidths of 225 and 650 MHz for data rates up to at least 800 Mb/sec using the 25.25 - 27.5 GHz space-to-space allocation. As part of NASA's acceptance of the TDRS-H spacecraft, an extensive on-orbit calibration, verification and characterization effort was performed to ensure that on-orbit spacecraft performance is within specified limits. This process verified the compliance of the Ka-band communications payload with all performance specifications, and demonstrated an end-to-end Ka-band service capability. This paper summarizes the results of the TDRS-H Ka-band communications payload on-orbit performance verification and end-to-end service characterization. Performance parameters addressed include antenna gain pattern, antenna Gain-to-System Noise Temperature (G/T), Effective Isotropically Radiated Power (EIRP), antenna pointing accuracy, frequency tunability, channel magnitude response, and Ka-band service Bit-Error-Rate (BER) performance.

Toral, Marco↗
NASA NTRS2002

On-Orbit Performance Verification and End-to-End Characterization of the TDRS-H Ka-Band Communications Payload

In June 2000, NASA launched the first of three next generation Tracking and Data Relay Satellites (TDRS-H) equipped with a Ka-band forward and return service capability. This Ka-band service supports forward data rates up to 25 Mb/sec using the 22.55 - 23.55 GHz space-to-space allocation. Return services are supported via channel bandwidths of 225 and 650 MHz for data rates up to 800 Mb/sec (QPSK) using the 25.25 - 27.5 GHz space-to-space allocation. As part of NASA's acceptance of the TDRS-H spacecraft, an extensive on-orbit calibration, verification and characterization effort was performed to ensure that on-orbit spacecraft performance is within specified limits. This process verified the compliance of the Ka-band communications payload with all performance specifications and demonstrated an end-to-end Ka-band service capability. This paper summarizes the results of the TDRS-H Ka-band communications payload on-orbit performance verification and end-to-end service characterization. Performance parameters addressed include Effective Isotropically Radiated Power (EIRP), antenna Gain-to-System Noise Temperature (G/T), antenna gain pattern, frequency tunability and accuracy, channel magnitude response, and Ka-band service Bit-Error-Rate (BER) performance.

Toral, Marco↗
NASA NTRS2003

Keeping Communication Continuous

General Dynamics Decision Systems employees have played a role in supplying telemetry, tracking, and control (TT&C) and other communications systems to NASA and the U.S. Department of Defense for over 40 years. Providing integrated communication systems and subsystems for nearly all manned and unmanned U.S. space flights, the heritage of this Scottsdale, Arizona-based company includes S-band transceivers that enabled millions of Americans to see Neil Armstrong and hear his prophetic words from the Moon in 1969. More recently, Decision Systems has collaborated with NASA s Goddard Space Flight Center to develop transponders, wireless communications devices that pick up and automatically respond to an incoming signal, for NASA s Tracking and Data Relay Satellite System (TDRSS). Four generations of Decision Systems TDRSS transponders have been developed under Goddard s sponsorship. The company s Fourth Generation TDRSS User Transponder (TDRSS IV) allows low-Earth-orbiting spacecraft to communicate continuously with a single ground station at White Sands, New Mexico, through a constellation of geostationary relay satellites positioned at key locations around the Earth. In addition to the communications of forward link control commands and return link telemetry data, the TDRSS IV also supports spacecraft orbit tracking through coherent turn-around of a pseudo-noise ranging code and two-way Doppler tracking.When the NSBF adopted the use of global positioning system receivers for balloon position tracking, Decision Systems concluded that a simpler, noncoherent transceiver could provide the NSBF with the necessary TDRSS communications without the additional cost and complexity of a coherent transponder. The solution was to take the core design of the TDRSS IV Transponder, but remove the extra functionality that supported coherent turn-around. This would simplify the production effort, reduce the testing required, and result in a lower cost product with smaller size, weight, and power consumption. Once NSBF and Decision Systems agreed on a concept for this new product, known as the Multi-Mode Transceiver (MMT), the NSBF approached Goddard for approval and funding.

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