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Tracking and data relay satellite system configuration and tradeoff study. Volume 5: TDRS spacecraft design, part 1
A dual spin stabilized TDR spacecraft design is presented for low data rate (LDR) and medium data rate (MDR) user spacecraft telecommunication relay service. The relay satellite provides command and data return channels for unmanned users together with duplex voice and data communication channels for manned user spacecraft. TDRS/ground links are in the Ku band. Command links are provided at UHF for LDR users and S band for MDR users. Voice communication channels are provided at UHF/VHF for LDR users and at S band for MDR users. The spacecraft is designed for launch on the Delta 2914 with system deployment planned for 1978. This volume contains a description of the overall TDR spacecraft configuration, a detailed description of the spacecraft subsystems, a reliability analysis, and a product effectiveness plan.
Study of liquid slosh in the tracking and data relay satellite hydrazine tanks
An experimental study was conducted to provide data for evaluation of the parameters for an analytical mechanical model representation of liquid/interface dynamics in the TDRSS propellant tanks. Models were developed for two liquid-under ullage (forward tank) configurations and for one liquid-over-ullage (aft tank) configuration. However, additional test runs were conducted with liquids of different densities in both cases to allow separation of bladder stiffness and gravity effects under various simulated steady acceleration conditions. Both static and dynamic parameters are evaluated to provide a good prediction of observed results.
Applications of satellite data relay to problems of field seismology
A seismic signal processor was developed and tested for use with the NOAA-GOES satellite data collection system. Performance tests on recorded, as well as real time, short period signals indicate that the event recognition technique used is nearly perfect in its rejection of cultural signals and that data can be acquired in many swarm situations with the use of solid state buffer memories. Detailed circuit diagrams are provided. The design of a complete field data collection platform is discussed and the employment of data collection platforms in seismic network is reviewed.
Tracking and data relay satellite system (TDRSS) - A worldwide view from space
The development, performance levels, and operational use of the TDRSS satellite system are outlined. The TDRSS spacecraft were conceived in the mid-1960s by NASA as a means of using GEO-positioned satellites to eliminate existing ground stations. The main ground terminal becomes Goddard Space Flight Center, through which users other than the Shuttle can also gain access. The TDRSS functions as a relay vehicle, with very little on-board processing except for status reports inserted into the data stream. Use of the TDRSS system by nonNASA agencies currently costs $110/min for forwards, return, and tracking, $24/min for forward service alone, and $8/min for return service only. The spacecraft can store data on board and dump it to the ground station during the limited hours of operation.
Tracking and Data Relay Satellite System configuration and tradeoff study. Volume 3: Atlas Centaur launched TDRSS. Part 2: Final Report, 22 August 1972 - 1 April 1973
Configuration data and design information for the Atlas Centaur launched configuration are presented. Overall system definition, operations and control, and telecommunication service system, including link budgets, are discussed. A brief description of the user telecommunications equipment and ground station is presented. A summary description of the TDR spacecraft and all the subsystems is included. The data presented are largely in tabular form. A brief treatment of an optional configuration with enhanced telecommunications service is described.
Tracking and Data Relay Satellite System configuration and tradeoff study. Volume 4: Space shuttle launched TDRSS. Part 2: Final Report, 22 August 1972 - 1 April 1973
Configuration data and design information for the space shuttle launched configuration is presented. The overall system definition, operations and control, and telecommunication service system including link budgets are discussed. A brief description of the user transceiver and ground station is presented. A final section includes a summary description of the TDR spacecraft and all the subsystems. The data presented are largely in tabular form.
Tracking and Data Relay Satellite System configuration and tradeoff study. Volume 2: Delta 2914 launched TDRSS, Configuration 2. Part 2: Final Report, 22 August 1972 - 1 April 1973
Configuration data and design information for a Delta 2914 launched configuration with greatly enhanced telecommunication service over the Part I Delta 2914 configuration is contained. The overall system definition, operations and control, and telecommunication service system, including link budgets are discussed. A brief description of the user transceiver and ground station is presented. A final section includes a summary description of the TDR spacecraft and all the subsystems. The data presented are largely in tabular form.
Tracking and Data Relay Satellite System /TDRSS/ telecommunication services
The TDRSS and tracking services define the telecommunication performance of the TDRSS between the RF interface with user spacecraft and the data interface with NASCOM at the ground terminal. Attention is given to system constraints, forward link services, multiple-access signal design parameters, S-band single access signal design parameters, multiple-access return link services, and single-access return link services.
Tracking and Data Relay Satellite System (TDRSS) Support of User Spacecraft without TDRSS Transponders
NASA GSFC VNS TSG personnel have proposed the use of TDRSS to obtain telemetry and/or S-band one-way return Doppler tracking data for spacecraft which do not have TDRSS-compatible transponders and therefore were never considered candidates for TDRSS support. For spacecraft with less stable local oscillators (LO), one-way return Doppler tracking data is typically of poor quality. It has been demonstrated using UARS, WIND, and NOAA-J tracking data that the simultaneous use of two TDRSS spacecraft can yield differenced one-way return Doppler data of high quality which is usable for orbit determination by differencing away the effects of oscillator instability.
Telemetry and data relay for manned space programs
Previously and currently planned methods of transferring or relaying telemetered information from a remote receiving station to the Mission Control Center, at the National Aeronautics and Space Administration Lyndon B. Johnson Space Center, are discussed. The data flow techniques of the Apollo Program (fixed formats), the Skylab Program (data compression), and the Space Shuttle Program (data throughput) are defined and analyzed according to their advantages and deficiencies from an operations viewpoint. Excluded from the data flow technique discussions are command data, tracking data, television data, and Teletype and Datafax messages. Voice transmissions are addressed in the Space Shuttle Program discussion because they form a part of the telemetry data stream. The tradeoffs between actual data flow requirements and existing communications limitations are addressed for each of these programs. Finally, a short discussion of current problem areas in the planned ground data transmission system for the Space Shuttle Program is presented.
Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company 40.0 ampere hour nickel cadmium spacecraft cells for the tracking data relay satellite system
Average end of charge voltages and pressures, and capacity output in ampere hours are presented. Test limits specify those values at which a cell is to be terminated from charge or discharge. Requirements are based on past cell performance data. The requirement does not constitute a limit for discontinuance from testing. The nickel cadmium batteries were screened for internal shorts, low capacity, electrolyte leakage, or inability of any cell to recover its open circuit voltage above 1.150 volts during the internal short test.
Tracking and data relay satellite system configuration and tradeoff study. Volume 2: System engineering, part 1, final report
All elements of the TDRS system were studied with emphasis on the design of a 3-axis stabilized satellite, and a telecommunication system optimized for support of low and medium data rate user spacecraft constrained to be launched on a Delta 2914. The research is reported to upgrade the spacecraft design to provide telecommunications support low, medium and high data rate users, considering launches with the Atlas/Centaur and the space shuttle. For Vols. 4, 5, 7, and 8, see N74-10809 through N74-10812.
The effect of radio frequency interference on the 136- to 138-MHz return link and 400.5- to 401.5-MHz forward link of the Tracking and Data Relay Satellite System
The purpose is to update the RFI estimates in the 136- to 138-MHz VHF band and to make estimates for the first time for the 400.5- to 401.5-MHz UHF band. These preliminary predictions are based on primarily ITU frequency-registration data, with missing data bridged by engineering judgement.
Enabling International Data Relay at Mars
The most commonly used mode of communications be-tween Earth and a Mars surface mission is ultra-high fre-quency (UHF) radio relay via a Mars orbiter. There are four orbiters and two surface rovers operating at Mars and by October there should be five orbiters and three landers or rovers. There has been some collaboration between ESA’s Mars Express orbiter and NASA’s rovers, but 2016 is when Mars relay becomes fully international. In October, ESA will deliver the ExoMars Trace Gas Orbiter (TGO) and En-try, Descent, and Landing (EDL) Demonstrator Module (EDM) lander to Mars. The ExoMars program includes both ESA and ROSCOSMOS, with NASA participation (the Electra UHF transceiver on TGO). NASA orbiters will pro-vide relay for EDM and future ESA Mars landers and rov-ers. TGO will provide relay for NASA's current and future surface assets (as Mars Express will continue to do). Inter-national collaboration is enabled in several steps. At the in-struction of the space agencies, the Mars mission projects negotiate and write a “Service Agreement.” This describes at a high level how a new Mars orbiter would operate with its corresponding surface missions or how a new surface mis-sion would operate with its corresponding orbiters. It in-cludes the roles of the different projects, how the new mis-sion would communicate with existing or planned missions, the general flow of data and commands, and the capabilities or requirements of the new mission. After completing the Service Agreement, the projects write Interface Control Doc-uments (ICDs), each of which describes data and command flow in greater detail and quantitative aspects of the relay link and operations timeline between an orbiter and a cor-responding lander/rover. Interfaces and operations are test-ed before a new mission arrives at Mars. Once at Mars, a new orbiter performs some “practice” relay contacts with its partners. For a new lander (e.g. EDM), relay operations gen-erally begin before atmospheric entry at Mars, with record-ing of the UHF relay signal from the lander (including open-loop wide-bandwidth recording) as it enters and traverses Mars’s atmosphere and lands on its surface. After Mars EDL or orbit injection, each relay contact is negotiat-ed and scheduled using the Mars Relay Operations Service (MaROS). This paper describes the international approach to develop inter-agency agreements, inter-project interfaces, and specifics of how MaROS is used in actual relay opera-tions between international partners.
Sensitivity of high-accuracy Tracking and Data Relay Satellite System (TDRSS) user spacecraft orbit determination to tracking schedules
The results of a study to analyze the dependence of TDRSS user spacecraft orbit determination consistencies on varying tracking schedules are presented. In this study, the TDRS-East orbit determination results obtained utilizing Bilateration Ranging Transponder System data were evaluated. Six state parameters, three position and three velocity components and the solar radiation pressure coefficient, are estimated for TDRS-East. It is concluded that, in order to achieve high-precision orbit determination, the tracking coverage should not fall below 10 minutes every two orbits as decreasing it to every four orbits will significantly degrade the accuracy; present state-of-the-art consistency in orbit determination using TDRSS tracking is approximately 15 to 20 meters.
Space data relay systems
Significant progress has been achieved in simplifying platform concepts through random access techniques. This is particularly important in applications such as balloons where weight is critical. In applications, where weight restriction may not be a problem, the concept lends itself to uncomplicated designs and low cost. Nevertheless, ordered systems offer inherent advantages in managing data flow which justifies their use. With continuing improvements in technology, particularly low power receivers, ordered systems should become quite competitive with random systems for many applications.
Tracking and Data Relay Satellite (TDRS) tracking and orbit determination
Analysis results were derived using the Goddard Trajectory Determination System to determine the orbit of TDRS-East. A batch weighted least-squares algorithm is used to fit the Bilateration Ranging Transponder system tracking measurements. Six state parameters (position and velocity components) and the solar radiation pressure coefficient are estimated. The solutions are obtained by fitting the data over 34 hr arcs that overlap by 10 hr. Ephemerides are generated over the 34 hr arcs and then compared over the overlapping regions. The position differences indicate the consistency of the solutions and give a measure of their accuracy. The effect of the modeling of perturbative forces (solar radiation pressure, nonspherical geopotential field) on these results are studied. Error analysis is performed using the ORAN program to estimate the effect of force-model errors and measurement-related errors on the TDRS-East ephemeris.