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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements.

Nemesure, M.↗
NASA NTRSDate not supplied

An Envisioned Future for Space Optical Communications

Since the beginning of the Space Age, NASA has been a leader in developing space communications and navigation technologies— especially during the Apollo missions to the Moon and NASA’s initial foray into deep space. To support future exploration and science needs, NASA is gradually introducing optical communications technologies to augment its radio frequency (RF) systems. Optical communications will enable new science and exploration missions by providing high data rates and better navigation over long distances. NASA has already flown several optical communications demonstrations, including the Lunar Laser Communications Demonstration (LLCD), the Laser Communications Relay Demonstration (LCRD), and the Terabyte Infrared Delivery (TBIRD) system. Historically, NASA has partnered with the Jet Propulsion Laboratory (JPL) and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) to develop optical communications technology. In addition to pursuing optical communications, NASA’s Space Communications and Navigation (SCaN) Program is undergoing a paradigm shift and moving away from government owned and operated networks to using commercial services whenever possible. In partnership with SCaN, NASA’s Space Technology Mission Directorate (STMD) has identified key technologies that need to be developed to support future space communications and navigation, including enhanced RF, optical, and 3rd Generation Partnership (3GPP) cellular capabilities, as well as high-speed networking. This paper briefly describes some current and upcoming optical demonstrations and provides an overview of STMD’s envisioned future for optical communications and navigation in the 2030+ timeframe.

Bernard L Edwards↗
NASA NTRS1987

Tropical rainfall measuring mission (TRMM)

By measuring rainfall in the tropics, the Tropical Rainfall Measuring Mission (TRMM) will make possible the understanding of the heat engine that drives the global weather. The TRMM mission parameters are given, and the spacecraft is described. The instruments are examined, including the precipitation radar, TRMM microwave radiometer, and Advanced Very High Frequency Radiometer. The mission life is addressed, including atmospheric data, fuel consumption, and life extension methods. The spacecraft interfaces, payload configuration, and deployment sequence are considered. The subsystems are described, including propulsion, power, command, data handling, and tracking. A Japanese Experimental Data Relay Tracking Satellite experimental package working with TRMM is briefly addressed.

Keating, Thomas↗
NASA NTRS2008

GPS Metric Tracking Unit

As Global Positioning Satellite (GPS) applications become more prevalent for land- and air-based vehicles, GPS applications for space vehicles will also increase. The Applied Technology Directorate of Kennedy Space Center (KSC) has developed a lightweight, low-cost GPS Metric Tracking Unit (GMTU), the first of two steps in developing a lightweight, low-cost Space-Based Tracking and Command Subsystem (STACS) designed to meet Range Safety's link margin and latency requirements for vehicle command and telemetry data. The goals of STACS are to improve Range Safety operations and expand tracking capabilities for space vehicles. STACS will track the vehicle, receive commands, and send telemetry data through the space-based asset, which will dramatically reduce dependence on ground-based assets. The other step was the Low-Cost Tracking and Data Relay Satellite System (TDRSS) Transceiver (LCT2), developed by the Wallops Flight Facility (WFF), which allows the vehicle to communicate with a geosynchronous relay satellite. Although the GMTU and LCT2 were independently implemented and tested, the design collaboration of KSC and WFF engineers allowed GMTU and LCT2 to be integrated into one enclosure, leading to the final STACS. In operation, GMTU needs only a radio frequency (RF) input from a GPS antenna and outputs position and velocity data to the vehicle through a serial or pulse code modulation (PCM) interface. GMTU includes one commercial GPS receiver board and a custom board, the Command and Telemetry Processor (CTP) developed by KSC. The CTP design is based on a field-programmable gate array (FPGA) with embedded processors to support GPS functions.

Source record↗
NASA NTRS1986

Very long baseline interferometric observations made with an orbiting radio telescope

An orbiting spacecraft and ground observatories have been used to obtain interferometric observations of cosmic radio sources. The Tracking and Data Relay Satellite System (TDRSS) was used as the orbiting observatory in conjunction with two 64-meter radio telescopes at ground observatories, one in Australia and one in Japan. The quasars 1730-130 (NRAO 530), 1510-089, and 1741-038 were observed at a frequency of 2.3 gigahertz, and a maximum projected baseline of 1.4 earth diameters was achieved. All quasar observations for which valid data were acquired resulted in detected fringes. Many of the techniques proposed for a dedicated very long baseline interferometry observatory in space were used successfully in this experiment.

Levy, G. S.↗
NASA NTRS1996

New TDRSS communications options for small satellites

The NASA uses a space network which includes the tracking and data relay satellite system (TDRSS) for the provision of reliable low data rate and high data rate relay services between user spacecraft in earth orbit and the ground. In relation to future small satellite designs, new communication options for the TDRSS support of small spacecraft missions are reported on. The technologies considered include new transponder technologies, evolution to Ka band frequencies and a TDRSS demand access service capability. Multiple access aspects are considered.

Zillig, David J.↗
NASA NTRS1973

GRAN experiment

A global system for search and rescue was studied to reduce the time lost between a mishap and rescue efforts. The sequence of the GRAN concept proceeds as follows: (1) A distress call is initiated by a survivor and consists of the retransmission of Omega tones and a unique identifying code. (2) Signals are frequency translated through the satellite from UHF to SHF. (3) The received signals are processed in real-time using improved skywave correction and lane ambiguity techniques. The results are processed in geographical coordinates, time of day, and unique ID. This information is then relayed to the closest rescue agent. The Omega system is described, and the satellite/GRAN compatibility is discussed. The program plan and schedule are included.

Morakis, J. C.↗
NASA NTRS1973

Low cost automated precise time measurement system

The Aerospace Guidance and Metrology Center (AGMC) has the responsibility for the dissemination of Precise Time and Time Interval (PTTI) to Air Force timing systems requiring microsecond time. In order to maintain traceability to the USNO Master Clock in Washington D.C., and accomplish efficient logging of time and frequency data on individual precision clocks, a simple automatic means of acquiring precise time has been devised. The Automatic Time Interval Measurement System (ATIMS) consists of a minicomputer (8K Memory), teletype terminal, electronic counter, Loran C receiver, time base generator and locally-manufactured relay matrix panel. During the measurement process, the computer controls the relay matrix which selects for comparison 13 atomic clocks against a reference clock and the reference versus Loran C. Through use of the system teletype, the operator is able to set the system clock (hours, minutes and seconds), examine and/or modify all clock data and constants, and set measurement intervals. This is done in a conversational manner. A logic flow diagram, system schematic, source listing and software components are included in the presentation.

Alpert, A.↗
NASA NTRS1986

NASA 60 GHz intersatellite communication link definition study. Baseline document

The overall system and component concepts for a 60 GHz intersatellite communications link system (ICLS) are described. The ICLS was designed to augment the capabilities of the current Tracking and Data Relay Satellite System (TDRSS), providing a data rate capacity large enough to accommodate the expected rates for user satellites (USAT's) in the post-1995 timeframe. The use of 60 GHz for the anticipated successor to TDRSS, the Tracking and Data Acquisition System (TDAS), was selected because of current technology development that will enable multigigibit data rates. Additionally, the attenuation of the earth's atmosphere at 60 GHz means that there is virtually no possibility of terrestrially generated interference (intentional or accidental) or terrestrially based intercept. The ICLS includes the following functional areas: (1) the ICLS payload package on the GEO TDAS satellite that communicates simultaneously with up to five LEO USAT's; (2) the payload package on the USAT that communicates with the TDAS satellite; and (3) the crosslink payload package on the TDAS satellite that communicates with another TDAS satellite. Two methods of data relay on-board the TDAS spacecraft were addressed. One is a complete baseband system (demod and remod) with a bi-directional 2 Gbps data stream; the other is a channelized system wherein some of the channels are baseband and others are merely frequency translated before re-transmission. Descriptions of the TDAS antenna, transmitter, receiver, and mechanical designs are presented.

Source record↗
NASA NTRS1991

Analysis of navigation performance for the Earth Observing System (EOS) using the TDRSS Onboard Navigation System (TONS)

Use of the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) was proposed as an alternative to the Global Positioning System (GPS) for supporting the Earth Observing System (EOS) mission. The results are presented of EOS navigation performance evaluation with respect to TONS based orbit, time, and frequency determination (OD/TD/FD). Two TONS modes are considered: one uses scheduled TDRSS forward link service to derive one way Doppler tracking data for OD/FD support (TONS-I); the other uses an unscheduled navigation beacon service (proposed for Advanced TDRSS) to obtain pseudorange and Doppler data for OD/TD/FD support (TONS-II). Key objectives of the analysis were to evaluate nominal performance and potential sensitivities, such as suboptimal tracking geometry, tracking contact scheduling, and modeling parameter selection. OD/TD/FD performance predictions are presented based on covariance and simulation analyses. EOS navigation scenarios and the contributions of principal error sources impacting performance are also described. The results indicate that a TONS mode can be configured to meet current and proposed EOS position accuracy requirements of 100 and 50 m, respectively.

Elrod, B.↗
NASA NTRS1993

Precise navigation for the Earth Observing System (EOS)-AM1 spacecraft using the TDRSS Onboard Navigation System (TONS)

As the baseline navigation system for the Earth Observing System (EOS)-AM1 spacecraft, the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) is required to provide precise position and velocity information for imaging instrument calibration and routine operations. This paper presents the results of real-time navigation performance evaluations with respect to TONS-based orbit and frequency determination to satisfy this requirement. Both covariance and simulation analysis of EOS-AM1 navigation accuracy and analysis using operational data from Landsat-4 are presented. Local (half orbit) and global (multiple orbits) tracking are considered using a way-forward link services. Improvements in navigation accuracies by using enhanced gravity models beyond the Goddard Earth Model (GEM)-T3 are also discussed. Key objectives of the analysis are to evaluate nominal performance and potential sensitivities and to address algorithm improvements such as TDRS ephemeris biasing, ionosphere model, and gravity process noise models slated for implementation. Results indicate that TONS can be configured to meet the proposed instrument navigation requirements of 20 meters, 3-sigma.

Folta, David C.↗
NASA NTRS1990

Acquisition of the QPSK demodulator in the presence of interference

The acquisition behavior of the tracking and data relay satellite system (TDRSS) receiver (a quadrative phase-shift keying (QPSK) demodulator using a dither lock detector) in the presence of interference from another user has been analyzed using a simulation model. The demodulator is composed of an automatic gain control, a QPSK Costas loop, a frequency sweep unit, lock test units, and a control unit. The simulation model has been tested for the following variables: signal and interference Doppler frequencies and phase offsets (with respect to initial voltage control oscillator setup), signal-to-interference ratio (SIR), and signal I/Q power ratio. The simulation results are discussed.

Ghazvinian, Farzad↗
NASA NTRS1991

Preliminary navigation accuracy analysis for the TDRSS Onboard Navigation System (TONS) experiment on EP/EUVE

A Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) is currently being developed by NASA to provide a high accuracy autonomous navigation capability for users of TDRSS and its successor, the Advanced TDRSS (ATDRSS). The fully autonomous user onboard navigation system will support orbit determination, time determination, and frequency determination, based on observation of a continuously available, unscheduled navigation beacon signal. A TONS experiment will be performed in conjunction with the Explorer Platform (EP) Extreme Ultraviolet Explorer (EUVE) mission to flight quality TONS Block 1. An overview is presented of TONS and a preliminary analysis of the navigation accuracy anticipated for the TONS experiment. Descriptions of the TONS experiment and the associated navigation objectives, as well as a description of the onboard navigation algorithms, are provided. The accuracy of the selected algorithms is evaluated based on the processing of realistic simulated TDRSS one way forward link Doppler measurements. The analysis process is discussed and the associated navigation accuracy results are presented.

Gramling, C. J.↗
NASA NTRS1986

NASA 60 GHz intersatellite links definition study. Final Review

Viewgraphs are presented which outline the overall system and component concepts for a 60 GHz intersatellite communications link system (ICLS). The ICLS was designed to augment the capabilities of the current Tracking and Data Relay Satellite System (TDRSS), providing a data rate capacity large enough to accommodate the expected rates for user satellites (USAT's) in the post-1995 timeframe. Two methods of data relay on-board the planned TDAS (Tracking and Data Acquisition) satellites are described. One is an all-baseband system with a bi-directional 2 Gbps data stream; the other is a channelized crosslink system wherein some of the channels are baseband and others are merely frequency translated before re-transmission. The general system and technology design drivers are outlined along with the acquisition architecture design. Descriptions of the TDAS antenna, transmitter, receiver, and mechanical hardware are presented.

Source record↗
NASA NTRS1982

New CCIR papers on telecommunications for deep space research

The selection of preferred frequency bands for deep space telecommunications in the 20 to 120 GHz range is discussed. The performance of links between Earth stations and stations in deep space is affected by the atmosphere of the Earth. Attenuation and emission by the atmosphere generally limits deep space telecommunications to frequencies below 20 GHz. There are, however, certain frequency bands in the 20 to 120 GHz range where atmospheric attenuation is low enough to permit links between Earth stations and deep space stations. Additionally there are certain other bands in the 20 to 120 GHz range that would be particularly suitable for links between an Earth orbiting relay station and deep space stations.

Oldegroot, N. F.↗
NASA NTRS2010

An Optimizing Space Data-Communications Scheduling Method and Algorithm with Interference Mitigation, Generalized for a Broad Class of Optimization Problems

NASA's space data-communications infrastructure, the Space Network and the Ground Network, provide scheduled (as well as some limited types of unscheduled) data-communications services to user spacecraft via orbiting relay satellites and ground stations. An implementation of the methods and algorithms disclosed herein will be a system that produces globally optimized schedules with not only optimized service delivery by the space data-communications infrastructure but also optimized satisfaction of all user requirements and prescribed constraints, including radio frequency interference (RFI) constraints. Evolutionary search, a class of probabilistic strategies for searching large solution spaces, constitutes the essential technology in this disclosure. Also disclosed are methods and algorithms for optimizing the execution efficiency of the schedule-generation algorithm itself. The scheduling methods and algorithms as presented are adaptable to accommodate the complexity of scheduling the civilian and/or military data-communications infrastructure. Finally, the problem itself, and the methods and algorithms, are generalized and specified formally, with applicability to a very broad class of combinatorial optimization problems.

Rash, James L.↗
NASA NTRS2018

Commissioning of NASA's 3rd Generation Tracking and Data Relay Satellites (TDRS KLM)

In the summer of 2017, the third and final spacecraft of the 3rd generation of the Tracking and Data Relay Satellites (TDRS) launched aboard an Atlas V rocket from Complex 41 on the Eastern Test Range. Finishing final testing and integration in the first quarter of 2018, the TDRS-M communication and navigation satellite completes a constellation that began service in the early 1980s. The 3rd generation of spacecraft, TDRS-K, L, and M, not only provided beneficial systems engineering lessons in handling anomalous Radio Frequency and Doppler interference as well as integrating new spacecraft into an aging ground support infrastructure, but also supplies NASA with a valuable test bed for new operational concepts and technologies useful in defining the future architecture of the NASA Space Network. This paper presents an overview of the TDRS-K, L, and M missions, including transfer orbit, Level 5 bus and payload testing, and finally NASA-led Level 6 testing, which includes active TDRS System (TDRSS) users. Highlights include relevant testing results, commissioning challenges, and lessons learned. The final discussion includes a brief overview of future NASA communication and navigation technologies and network architectures.

Data Relay↗
NASA NTRSDate not supplied

International Coordination and Cooperation on LunaNet Spectrum

LunaNet is planned to be the network of networks operated by a set of cooperating organizations to provide interoperable Communications, networking, Position, Navigation, and Timing (CPNT) services to users on and around the Moon based on a framework of mutually agreed-upon standards, protocols, frequency bands and interface requirements. LunaNet follows a service-oriented architecture that is agnostic about the types of organizations that provide services, e.g., government, industry, or academia. LunaNet is open, scalable, resilient, secure, and extensible. To achieve these goals, LunaNet Service Providers (LNSP) must coordinate with each other to define and develop the architecture, to plan initial and evolved capabilities, and to operate their networks. One of the central LunaNet tenets is the use of shared spectrum. For example, the Lunar Augmented Navigation Service (LANS) acts like a Global Navigation Satellite System (GNSS) such as the US Global Positioning System (GPS) or European Galileo but the LNSPs’ contributions to LunaNet must use the same frequency band (2483.5 MHz-2500.0 MHz) and transmit the same waveform synchronized by highly accurate clocks so that Users ‘see’ one virtual network and use the same multilateration algorithm to determine their positions. This necessitates a high degree of spectrum coordination. NASA’s Lunar and Human Spaceflight Spectrum Management Team has been actively supporting development of the LunaNet Interoperability Specification (LNIS), soliciting inputs from spectrum policy and planning experts across NASA, ESA and JAXA. Cislunar spectrum use considerations have been studied and adjudicated within the Space Frequency Coordination Group (SFCG) and inform the ongoing discussion of a lunar communication and navigation architecture within the existing radio regulatory framework of the International Telecommunication Union, leading to the 2027 World Radiocommunication Conference (WRC-27). The frequency plan contained in the publicly released draft of the LunaNet Interoperability Specification reflects the initial phase of exploration (roughly to 2030) defining an optimal set of radio frequencies in appropriately allocated services consistent with WRC-23 decisions for use by known or planned CPNT applications, while striving to maximize coexistence and compatibility amongst cislunar systems and other systems within the near-Earth regime (< 2 million km from Earth). Important considerations include: protection of extremely sensitive receive-only radio astronomy systems on the lunar far side, known as the Shielded Zone of the Moon (SZM); compatibility between Direct with Earth (DWE) communications links and links needed to support relay satellites in lunar orbit with their customer systems on orbit or on the lunar surface; compatibility between multiple lunar surface communications systems and capabilities over varied and challenging terrain and distances; as well as ensuring compatibility and interoperability between navigation systems which either leverage Earth-based or in-situ lunar systems. In addition, the lunar CPNT architecture is envisioned to be the basis – with adjustments – of the future Mars CPNT architecture as we expand into the solar system using Interplanetary Networking (IPN). The second phase of lunar spectrum definition will address planned international capabilities for the next decade that will require action at WRC-27 and beyond. This paper will discuss each of these considerations in more depth and how the current LunaNet frequency plan addresses them.

LunaNet↗