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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 73 records · Page 4

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NASA NTRS1972

The Mariner Mars 1971 orbiter.

The Mariner Mars 1971 (MM '71) orbiter spacecraft, launched toward Mars in the spring of 1971, was designed to offer the first opportunity for sustained observations in the near vicinity of another planet of our solar system. The MM '71 spacecraft, like its predecessors, is fully attitude stabilized about three axes, using the sun and Canopus as references, an orientation which allows use of photovoltaic solar panels for primary power and permits two-way communication to the earth through a high-gain directional antenna. Midcourse and orbit insertion maneuvers use the sun-Canopus orientation as a reference direction for initiating commanded turns. Scientific instruments employed during Mars orbital operations are mounted on a two-degree-of-freedom platform controlled by commands from the central computer and sequencer. Science measurements to be obtained by the MM '71 spacecraft include television visual imaging, infrared radiometry, infrared spectroscopy, ultraviolet spectroscopy, S-band radio occultation, and celestial mechanics.

Scull, J. R.↗

NASA NTRS1973

A digital communications system for manned spaceflight applications.

A highly efficient, all-digital communications signal design employing convolutional coding and PN spectrum spreading is described for two-way transmission of voice and data between a manned spacecraft and ground. Variable-slope delta modulation is selected for analog/digital conversion of the voice signal, and a convolutional decoder utilizing the Viterbi decoding algorithm is selected for use at each receiving terminal. A PN spread spectrum technique is implemented to protect against multipath effects and to reduce the energy density (per unit bandwidth) impinging on the earth's surface to a value within the guidelines adopted by international agreement. Performance predictions are presented for transmission via a TDRS (tracking and data relay satellite) system and for direct transmission between the spacecraft and earth. Hardware estimates are provided for a flight-qualified communications system employing the coded digital signal design.

Batson, B. H.↗

NASA NTRS1971

Teleconferencing, an annotated bibliography, volume 3

In this annotated and indexed listing of works on teleconferencing, emphasis has been placed upon teleconferencing as real-time, two way audio communication with or without visual aids. However, works on the use of television in two-way or multiway nets, data transmission, regional communications networks and on telecommunications in general are also included.

Shervis, K.↗

NASA NTRS1973

Task one report: Optical system study

An optical system which can be incorporated in a present day or near future space-borne laser communications system is described. Techniques of implementing these systems are presented and their design problems and use are discussed. Optical system weight is estimated as a function of aperture diameter for a typical present day or near future laser communication system. The optical communications system considered is a two-way, high data rate optical communications link from a spacecraft to a spacecraft or from a spacecraft to a ground station. Each station has a laser transmitter and receiver and a pointing and tracking system. Thus each station can track the laser transmitter of the other. Optical beamwidths are considered to be as small as an arc-second with the beam pointed to a fraction of this beamwidth.

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NASA NTRS1974

The Deep Space Network

The objectives, functions, and organization, of the Deep Space Network are summarized. Deep Space stations, ground communications, and network operations control capabilities are described. The network is designed for two-way communications with unmanned spacecraft traveling approximately 1600 km from earth to the farthest planets in the solar system. It has provided tracking and data acquisition support for the following projects: Ranger, Surveyor, Mariner, Pioneer, Apollo, Helios, Viking, and the Lunar Orbiter.

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NASA NTRS1974

Venus - Mass, gravity field, atmosphere, and ionosphere as measured by the Mariner 10 dual-frequency radio system

The unique properties of the Mariner 10 radio system, and the preliminary scientific results obtained from the analysis of the radio signals are described. In the normal two-way communication mode, a command- and range-modulated 2115-MHz signal is transmitted to the spacecraft for reception on its omnidirectional antenna. As implemented for Mariner 10, the dual-frequency system has proven fully capable of performing interplanetary columnar electron content measurements while achieving the prime goals of the celestial mechanics and radio science team. The determination of the mass and gravitational potential of Venus is one of the major objectives of the radio science experiments. Information on Venus's atmosphere was deduced from analysis of the radio signals during occultation. Open-loop receiver differential Doppler data were used to measure the nightside and dayside ionospheres of Venus.

Howard, H. T.↗

NASA NTRS1974

On first cycle slip time of phase-locked loops in cascade

Precise measurement and spacecraft tracking are obtained by using phase-locked loops in cascade in two-way communications links. Statistics on cycle slip time are of vital importance in system planning and design. This paper presents: (1) results of a computer simulation study of the mean time to first cycle slip of cascade phase-locked loops preceded by bandpass limiters, and (2) the determination of probability distributions of cycle slip. Numerical results are obtained for a typical coherent communication system.

Yuen, J. H.↗

NASA NTRS1974

Relativity time-delay experiments utilizing 'Mariner' spacecraft

Relativity predicts that the transit time of a signal propagated from the earth to a spacecraft and retransmitted back to earth ought to exhibit an additional, variable time delay. The present work describes some of the analytical techniques employed in experiments using Mariner spacecraft designed to test the accuracy of this prediction. Two types of data are analyzed in these relativity experiments; these include phase-coherent, two-way Doppler shift and round-trip, transit-time measurements. Results of Mariner 6 and 7 relativistic time-delay experiments are in agreement with Einstein's theory of general relativity with an uncertainty of 3%.

Esposito, P. B.↗

NASA NTRS1974

Gravity results from Pioneer 10 Doppler data

Two-way Doppler data received from Pioneer 10 during its encounter with Jupiter have been analyzed, and preliminary results have been obtained on the mass and the gravity field of Jupiter and on the masses of the four Galilean satellites. The ratios of the masses of the satellites to the mass of Jupiter are approximately 0.00004696 for Io, 0.00002565 for Europa, 0.00007845 for Ganymede, and 0.00005603 for Callisto (all error estimates presented in this paper are standard errors; those for Pioneer 10 represent our evaluation of the real errors as distinguished from formal errors). The ratio of the mass of the sun to the mass of the Jupiter system is about 1047.342, which is in good agreement with recent determinations from the motions of asteroids. The second- and fourth-degree zonal harmonic coefficients in the gravity field of Jupiter are 0.014720 and -0.00065, respectively, based on an equatorial planetary radius of 71,400 km, and the derived dynamical oblateness is 0.0647 at the same radius. The Pioneer 10 data are consistent with the assumption that Jupiter is in hydrostatic equilibrium at all levels.

Anderson, J. D.↗

NASA NTRS1975

Simultaneous acquisition of tracking data from two stations

A method and apparatus is described for obtaining simultaneous tracking data from two ground stations relative to a spacecraft, and in particular for obtaining two-way range and Doppler measurements with respect to the spacecraft using only one transponder on the spacecraft. The technique employs simultaneous transmission from two stations to produce a return signal with upper and lower sidebands resulting from the interference of the two transmissions. A transponder transmits the upper and lower sidebands centered about a carrier received by both stations. One station tracks the carrier and the other tracks a sideband aided by the carrier.

Wood, G. E.↗

NASA NTRS1974

Statistical analysis of Skylab 3

The results of endocrine/metabolic studies of astronauts on Skylab 3 are reported. One-way analysis of variance, contrasts, two-way unbalanced analysis of variance, and analysis of periodic changes in flight are included. Results for blood tests, and urine tests are presented.

Johnston, D. A.↗

NASA NTRS1975

Automatic liquid inventory collecting and dispensing unit

A means is provided for automatically collecting waste liquids and for simultaneously feeding these liquids into water recovery processes. The invention includes first and second tanks with first and second two-way solenoid valves associated with each of the tanks. The first solenoid valve is connected to the liquid source and its associated tank so as to allow liquid to flow into the tank when the valve is in its normal position and to allow the liquid to flow out of the tank when the valve is in its actuated position. The second valve is connected to its associated tank and a gas supply so as to allow gas inside the tank to flow out when the valve is in its normal position and to allow gas to flow from the gas supply into the tank when the valve is in its actuated position. Control circuits are included for actuating the two valves associated with the first tank and not actuating the valves associated with the second tank. The first tank is filled and the second tank is emptied.

Hall, J. B., Jr.↗

NASA NTRS1974

Data link relay design

The data link for the Ames baseline probe as applied to the MJU spacecraft specifically with an entry at Uranus is analyzed. A frequency analysis, a trajectory analysis, and a discussion of the effects on the spacecraft design by the data link are presented. The possibilities of a two-way link are considered.

Parsons, P.↗

NASA NTRS1974

The design and use of an error correction information system for NASTRAN

Error Correction Information System (ECIS) is a system for a two-way transmittal of NASTRAN maintenance information via a data base stored on a nationwide accessible computer. ECIS consists of two data bases. The first data base is used for comments, reporting NASTRAN Software Problem Reports (SPR's) and bookkeeping information which can be updated by the user or the NASTRAN Office. The second data base is used by the NSMO to store all SPR information and updates. The hardware needed by an accessing user is any desktop computer terminal and a telephone to communicate with the central computer. The instruction format is an engineering oriented language and requires less than an hour to obtain a working knowledge of its functions.

Rosser, D. C., Jr.↗

NASA NTRS1974

Frequency standards requirements of the NASA deep space network to support outer planet missions

Navigation of Mariner spacecraft to Jupiter and beyond will require greater accuracy of positional determination than heretofore obtained if the full experimental capabilities of this type of spacecraft are to be utilized. Advanced navigational techniques which will be available by 1977 include Very Long Baseline Interferometry (VLBI), three-way Doppler tracking (sometimes called quasi-VLBI), and two-way Doppler tracking. It is shown that VLBI and quasi-VLBI methods depend on the same basic concept, and that they impose nearly the same requirements on the stability of frequency standards at the tracking stations. It is also shown how a realistic modelling of spacecraft navigational errors prevents overspecifying the requirements to frequency stability.

Fliegel, H. F.↗

NASA NTRS1975

Significance of biorhythms in space flight

Evidence is presented that the most important factor in the maintenance of optimal health and performance is the stability of the relationship of one body rhythm to another. The effect of social interaction on performance, well-being, and physiological rhythm synchrony was investigated. Three groups of healthy males, ages 21 to 25, were confined in rooms (3.4 by 5.2 meters (11 by 17 feet)) for a total period of 105 days. Two of the groups were in rooms in which the environment could be regulated. The third group served as the control group and was exposed to ambient experimental conditions. The confined subjects were exposed for periods to several days either to 16 hours of light and 8 hours of dark, or to continuous light at a light intensity of 161 lm/sq m (15 foot-candles). The confined subjects were deprived of all time cues, and meals were ad libitum. The subjects were observed throughout the study by a video camera and were scored for activity. Communications were limited to meal and sample-collection information, and meals and samples were passed through a two-way hatch. Rectal temperature and heart rate (HR) were sampled every 30 minutes by telemetry throughout the study. Results are presented.

Winget, C. M.↗

NASA NTRS1975

Long-range communications with Pioneer 10 at Jupiter

The longest two-way telecommunications link ever established connected Pioneer 10 with its controllers and experimenters on earth during the first Jovian encounter. This radio link, operating in the 2.1 and 2.3 gigahertz frequency bands, maintained high-quality communications over a distance of 5-1/2 astronomical units. The data collected by eleven on-board advanced scientific instruments were transmitted to the investigators, providing a new wealth of information about the largest planet of the solar system. A descriptive review is presented of the spacecraft design and the ground data system configuration with an analysis of the telecommunications downlink. Pioneer 10, aided by Jupiter's gravitational field, is the first spacecraft to leave the solar system. A plaque attached to the spacecraft represents man's first attempt to send a message to another intelligence within our galaxy.

Dickerson, L. W.↗

NASA NTRS1975

A distributed data base management system

Major system design features of a distributed data management system for the NASA Deep Space Network (DSN) designed for continuous two-way deep space communications are described. The reasons for which the distributed data base utilizing third-generation minicomputers is selected as the optimum approach for the DSN are threefold: (1) with a distributed master data base, valid data is available in real-time to support DSN management activities at each location; (2) data base integrity is the responsibility of local management; and (3) the data acquisition/distribution and processing power of a third-generation computer enables the computer to function successfully as a data handler or as an on-line process controller. The concept of the distributed data base is discussed along with the software, data base integrity, and hardware used. The data analysis/update constraint is examined.

Bryan, A. I.↗