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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Advanced 30/20 GHz communication satellites

Increasing demands for satellite communications channels have filled the C-band, have begun to fill the Ku-band, and have resulted in a developmental effort to utilize 2.5 GHz of the 30/20 GHz Ka band. Problems of rain attenuation in the Ku and Ka bands are explored, and solutions are indicated in the use of antenna gain coupled with ground terminal site diversity, and higher satellite power capabilities. Tradeoffs in satellite design are focused on the number of reflectors, increased f/d, gain and sidelobe performance, and total satellite capacity. The NASA 20/30 GHz program is described, including design features of two test systems to be launched in the 1980's to examine the functioning limits of two baseline systems.

Sivo, J. N.↗
DOE OSTI2025

2 Kelvin helium distribution system for the Electron Ion Collider’s 10 o’clock satellite refrigerator

The Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) will involve superfluid helium cooling of superconducting magnets and Superconducting Radio Frequency (SRF) cavities at several sites around the existing Relativistic Heavy Ion Collider (RHIC) accelerator tunnel. While the majority of the cooling power for these loads is provided by BNL’s central cryogenic plant, Jefferson Lab is designing satellite equipment which augments the central plant and enables 2 Kelvin operation. The 2 K cryogenic distribution system for the collider’s 10 o’clock location (Interaction Region 10 or IR10) includes all necessary interfaces to the IR10 Satellite Refrigerator, to the overall EIC cryogenic distribution system, and to 12 SRF cryomodules for the electron and hadron storage rings. In addition to providing the required cooling capacities in all operating modes, the IR10 2 K cryogenic distribution system also stabilizes the supply temperature and enables safe connection and disconnection of individual IR10 cryomodules. Moreover, the layout of the IR10 2 K cryogenic distribution system copes with challenging spatial constraints and adapts to the process configuration and routing of existing RHIC cryogenic distribution components which will be re-used for EIC. This paper gives a full overview of the IR10 satellite cryogenic distribution system design, and highlights some of the challenges encountered.

Laverdure, Nathaniel [Thomas Jefferson National Ac↗
NASA NTRS1973

The Air Density Explorer Satellite Program

Since 1961, four satellites designed specifically for determination of the density and composition variations of the earth's neutral atmosphere at satellite altitudes have been launched: Explorer 9, Explorer 19, Explorer 24, and Explorer 39. Studies of the orbital decay of these satellites have resulted in major revisions in our conception of the upper atmosphere at satellite altitudes. These features include the winter helium bulge detected near 1000 km with its north-south asymmetry, the summer atomic oxygen bulge near 500 km, and the winter enhancement of atomic oxygen near 120 km. The Langley Research Center is now in the process of designing and fabricating the Dual Air Density Explorers. These will be two satellites launched by means of a single Scout rocket in 1975, and they are expected to remain in essentially the same orbital plane throughout the 2-year mission. Each satellite is drag sensitive and uses a mass spectrometer in a unique system which is insensitive to orientation, is highly sensitive to the upper atmosphere, and is capable of in-flight calibration.

Keating, G. M.↗
NASA NTRS1991

A preliminary design for a satellite power system

Outlined here is a preliminary design for a Solar Power Satellite (SPS) system. The SPS will provide a clean, reliable source of energy for mass consumption. The system will use satellites in geostationary orbits around the Earth to capture the sun's energy. The intercepted sunlight will be converted to laser beam energy which can be transmitted to the Earth's surface. Ground systems on the Earth will convert the transmissions from space into electric power. The preliminary design for the SPS consists of one satellite in orbit around the Earth transmitting to one ground station. The SPs technology uses multi-layer solar cell technology arranged on a 20 sq km planar array to intercept sunlight and convert it to an electric voltage. Power conditioning devices then send the electricity to a laser, which transmits the power to the surface of the Earth. A ground station will convert the beam into electricity. Construction will take place in low Earth orbit and array sections, 20 in total, will be sailed on the solar wind out to the GEO location in 150 days. These individual transportation sections are referred to as solar sailing panels (SSAPs). The primary truss elements used to support the arrays are composed on composite tubular members in a pentahedral arrangement. Smart segments consisting of passive and active damping devices will increase the control of dynamic SPS modes.

Enriquez, Clara V.↗
NASA NTRS1976

Earth observations from space

The present state of satellites designed for earth observations is reviewed. Particular attention is given to operational meteorological satellites, experimental atmosphere and ocean satellites, and earth resources satellites. Examples of applications resulting from satellite earth observations are discussed. It is concluded that earth observations from space have greatly advanced man's understanding of atmospheric, oceanic, and geological processes, opening the way to a large number of viable applications.

Nordberg, W.↗
NASA NTRS1989

Spacecraft design project: High latitude communications satellite

The spacecraft design project was part of AE-4871, Advanced Spacecraft Design. The project was intended to provide experience in the design of all major components of a satellite. Each member of the class was given primary responsibility for a subsystem or design support function. Support was requested from the Naval Research Laboratory to augment the Naval Postgraduate School faculty. Analysis and design of each subsystem was done to the extent possible within the constraints of an eleven week quarter and the design facilities (hardware and software) available. The project team chose to evaluate the design of a high latitude communications satellite as representative of the design issues and tradeoffs necessary for a wide range of satellites. The High-Latitude Communications Satellite (HILACS) will provide a continuous UHF communications link between stations located north of the region covered by geosynchronous communications satellites, i.e., the area above approximately 60 N latitude. HILACS will also provide a communications link to stations below 60 N via a relay Net Control Station (NCS), which is located with access to both the HILACS and geosynchronous communications satellites. The communications payload will operate only for that portion of the orbit necessary to provide specified coverage.

Josefson, Carl↗
NASA NTRS1994

Small satellite space operations

CTA Space Systems has played a premier role in the development of the 'lightsat' programs of the 80's and 90's. The high costs and development times associated with conventional LEO satellite design, fabrication, launch, and operations continue to motivate the development of new methodologies, techniques, and generally low cost and less stringently regulated satellites. These spacecraft employ low power 'lightsat' communications (versus TDRSS for NASA's LEO's) and typically fly missions with payload/experiment suites that can succeed, for example, without heavily redundant backup systems and large infrastructures of personnel and ground support systems. Such small yet adaptable satellites are also typified by their very short contract-to-launch times (often one to two years). This paper reflects several of the methodologies and perspectives of our successful involvement in these innovative programs and suggests how they might relieve NASA's mounting pressures to reduce the cost of both the spacecraft and their companion mission operations. It focuses on the use of adaptable, sufficiently powerful yet inexpensive PC-based ground systems for wide ranging user terminal (UT) applications and master control facilities for mission operations. These systems proved themselves in successfully controlling more than two dozen USAF, USN, and ARPA satellites at CTA/SS. UT versions have linked with both GEO and LEO satellites and functioned autonomously in relay roles often in remote parts of the world. LEO applications particularly illustrate the efficacy of these concepts since a user can easily mount a lightweight antenna, usually an omni or helix with light duty rotors and PC-based drivers. A few feet of coax connected to a small transceiver module (the size of a small PC) and a serial line to an associated PC establishes a communications link and together with the PC constitute a viable ground station. Applications included geomagnetic mapping; spaceborne solid state recorder validation; global store-and-forward data communications for both scientific and military purposes such as Desert Storm; UHF transponder services for both digital data and voice using a constellation; remote sensor monitoring of weather and oceanographic conditions; classified payloads; and UHF spectrum surveillance. Ground processing has been accomplished by automatic unattended or manual operation. Management of multiple assets highlights the relative ease with which two constellations totaling nine satellites were controlled from one system including constellation station keeping. Our experience in small end-to-end systems including concurrent design, development, and testing of the flight and operational ground systems offers low cost approaches to NASA scientific satellite operations of the 1990's.

Reiss, Keith↗
NASA NTRS1996

An Advanced Photovoltaic Array Regulator Module

Current trends in satellite design are focused on developing small, reliable, and inexpensive spacecraft. To that end, a modular power management and distribution system is proposed which will help transition the aerospace industry towards an assembly line approach to building spacecraft. The modular system is based on an innovative DC voltage boost converter called the Series Connected Boost Unit (SCBU). The SCBU uses any isolating DC-DC converter and adds a unique series connection. This simple modification provides the SCBU topology with many advantages over existing boost converters. Efficiencies of 94-98%, power densities above 1,000 W/kg, and inherent fault tolerance are just a few of the characteristics presented. Limitations of the SCBU technology are presented, and it is shown that the SCBU makes an ideal photovoltaic an-ay regulator. A set of photovoltaic power system requirements are presented that can be applied to almost any low Earth orbit satellite. Finally, a modular design based on the series connected boost unit is outlined and functional descriptions of the components are given.

Button, Robert M.↗
NASA NTRS2006

A Lunar Communications and Navigation Satellite Concept for the Robotic Lunar Exploration Program

The Second Robotic Lunar Exploration Program (RLEP) mission has two primary objectives. Broadly stated, they are "To See the Light" and "To Touch the Ice", meaning one mission objective is to survey the lighting conditions on the rim of a candidate crater over the course of a year, and the second objective is to descend into th.! s crater to search for water ice. The Space Communications Program Office at NASA/GSFC is supporting the RLEP-2 Project by developing a communications and navigation architecture for the mission. The primary candidate crater studied is the Shackleton Crater near the South Pole of the Moon. The rim of this crater has approximately 14 contiguous days of visibility to the Earth over the course of a month, while mission elements in the crater have no line of sight to either the Earth or potentially an element on the rim of the crater. One solution studied is to launch a relay spacecraft with RLEP-2 to provide communications and navigation services to the elements on the lunar surface. To support operations concepts requiring long duration contacts between the relay and the elements in the crater, an inclined elliptical orbit originally conceived by Todd Ely a t JPL was chosen for the relay. The orbit was adjusted to lower the maximum range while maintaining its "frozen" nature, meaning once placed in this orbit little delta-V is required for orbit maintenance. The orbital parameters were adjusted such that the relay has visibility into the crater for approximately 8.7 hours of the 12 hour orbital period. The relay satellite design draws heavily upon heritage concepts and hardware to achieve a very low risk implementation. The design concept is a 3-axis spacecraft that is capable of supporting return communication links from multiple surface elements concurrently through a four-element S-Band Multiple Access phased array with two forward links provided through single dedicated elements. The payload is a bent-pipe relay with beamforming performed on the ground (Earth). To mitigate concerns with multipath observed during Mars missions, the preliminary design employs PN-spread signal structures which have been used successfully by Tracking and Data Relay Satellite System (TDRSS) users for simultaneous real-time and recorded data playback. Details of the relay communication trade studies and rationale for the selected design elements are discussed in the paper.

Gramling, Jeffrey J.↗
NASA NTRS1991

Reusable Reentry Satellite (RRS) system design study: System cost estimates document

The Reusable Reentry Satellite (RRS) program was initiated to provide life science investigators relatively inexpensive, frequent access to space for extended periods of time with eventual satellite recovery on earth. The RRS will provide an on-orbit laboratory for research on biological and material processes, be launched from a number of expendable launch vehicles, and operate in Low-Altitude Earth Orbit (LEO) as a free-flying unmanned laboratory. SAIC's design will provide independent atmospheric reentry and soft landing in the continental U.S., orbit for a maximum of 60 days, and will sustain three flights per year for 10 years. The Reusable Reentry Vehicle (RRV) will be 3-axis stabilized with artificial gravity up to 1.5g's, be rugged and easily maintainable, and have a modular design to accommodate a satellite bus and separate modular payloads (e.g., rodent module, general biological module, ESA microgravity botany facility, general botany module). The purpose of this System Cost Estimate Document is to provide a Life Cycle Cost Estimate (LCCE) for a NASA RRS Program using SAIC's RRS design. The estimate includes development, procurement, and 10 years of operations and support (O&S) costs for NASA's RRS program. The estimate does not include costs for other agencies which may track or interface with the RRS program (e.g., Air Force tracking agencies or individual RRS experimenters involved with special payload modules (PM's)). The life cycle cost estimate extends over the 10 year operation and support period FY99-2008.

Source record↗
NASA NTRS1988

Communications satellite systems operations with the space station. Volume 3: Supplementary technical report

The NASA space station has the potential to provide significant economic benefits to commercial communications satellite operators. The initial reports qunatified the benefits of space-based activities and assessed the impacts on the satellite design and the space station. Results are given for the following additional tasks: quantify the value of satellite retrievability operations and define its operational aspects; evaluate the use of expendable launch vehicles for transportation of satellites from the Earth to the space station; and quantify the economic value of modular satellites that are assembled and serviced in space.

Price, K. M.↗
NASA NTRS1997

The advanced stellar compass onboard the Oersted satellite

The advanced stellar compass (ASC) star tracker installed onboard the Danish Oersted satellite designed to map the earth's magnetic vector field is presented. The ASC instrument will provide attitude data for the satellite and its payload. It consists of a CCD camera connected to a microcomputer, and operates by comparing star images from camera frames with its internal star catalogs. The instrument design is detailed, considering its key parameters, operating principles, and the different types of noise and error sources. A ground-based real sky evaluation and the calibration of the ASC are reported.

Jorgensen, John L.↗
NASA NTRS1990

Statistical interference prediction for ground stations from orbiting satellites. I - Simulation of interference duration and analytical approach for the determination of protection ratios

The authors describe simulation and analytical techniques for predicting the interference durations and protection ratios for deep-space ground stations from satellites in circular orbits. The simulation approach employs the characteristics of the ground station receivers in addition to the satellite specifications to calculate the daily statistics of the interference duration. On the other hand, the analytical method employs the ground station specifications to statistically predict the protection ratios as a function of the number of interference satellites and their associated probabilities. The results presented here can be used for both planning the missions and designing satellite communication links. The results can be also be used by spectrum managers and operations personnel to minimize the risk of harmful interference from satellites in low earth orbit to the deep space frequency band.

Gevargiz, John M.↗
NASA NTRS1995

Global tracking and inventory of military hardware via LEO satellite: A system approach and likely scenario

A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.

Bell, David↗