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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Titan/Centaur: NASA's newest launch vehicle

Titan/Centaur is NASA's last new expendable launch vehicle prior to the advent of the space shuttle. Titan/Centaur is an adaptation of the Air Force Titan 3 booster with an improved version of the Centaur stage and a new 4.2 meters payload fairing. Titan/Centaur is initially being used for high performance escape missions (Helios Solar Probe - 340 kilograms' Viking Mars Orbiter and Lander - 3,629 kilograms, and Mariner Jupiter/Saturn Fly-Bys at 771 kilograms, but is also particularly suited for larger spacecraft in synchronous orbits (transfer - 7,031 kilograms and equatorial, with three Centaur burns - 3,175 kilograms). The program which began in 1965 with internal NASA feasibility studies will culminate in a proof flight launch in early 1974. With the new payload fairing, which also encloses Centaur, payloads of nearly 8.5 meters long and 3.8 meters in diameter can be accommodated.

Stofan, A. J.↗
NASA NTRS1973

The Jet Propulsion Laboratory 7.62-m space simulator modification

The JPL 7.62-m space simulator was modified to simulate the solar intensities at the planet Mercury. The capability of the simulator was increased to support testing of both the Mariner spacecraft mission to Venus and Mercury (to be launched in 1973) and the Helios spacecraft. The design of the off-axis reflecting system of the JPL simulators allowed attaining increased solar intensity, at the expense of test area, by placing a smaller collimating mirror at a lower elevation in the space simulator. In addition to requiring a new collimating mirror 4.57-m in diameter, the optical integrating system required a new design and there were several other efforts necessary to support these primary alterations.

Morgan, N. R.↗
NASA NTRS1973

A biased model for calculating the evolution in solar absorptance.

A biased model is proposed to account for the smooth curve type of degradation experienced by spacecraft environmental interfacing materials. Because the space environment is nondestructive, the solar absorptance (alpha) must reach its maximum value in finite time, monotonically, without inflection points and be single valued, viz., alpha equals alpha-zero plus (Bt - D) exp (-At). A simple procedure is also included for the parametric calculation of A, B, and D with respect to solar intensity, particle flux, and temperature. The suitability of the model is discussed with regard to destructive testing, and a more general equation proposed. Use of the model for alpha calculations appropriate to the HELIOS missions is outlined.

Schutt, J. B.↗
NASA NTRS1973

Titan/Centaur - NASA's newest launch vehicle.

Titan/Centaur is NASA's last 'new-expendable' launch vehicle prior to the advent of the Space Shuttle. Titan/Centaur is an adaptation of the Air Force Titan III booster with an improved version of the Centaur stage and a new 4.2-meter payload fairing. Titan/Centaur is initially being used for high performance escape missions (Helios Solar Probe - 340 kilograms, Viking Mars Orbiter and Lander - 3,629 kilograms, and Mariner Jupiter/Saturn Fly-Bys at 771 kilograms), but is also particularly suited for larger spacecraft in synchronous orbits (transfer - 7,031 kilograms and equatorial, with three Centaur burns - 3,175 kilograms). The program which began in 1965 with internal NASA feasibility studies will culminate in a 'proof flight' launch in early 1974. With the new payload fairing, which also encloses Centaur, payloads nearly 8.5 meters long and 3.8 meters in diameter can be accommodated.

Stofan, A. J.↗
NASA NTRS1973

Thermally oscillating actuators

The actuator was redesigned to accommodate the new thermal motor for the Helios flipper. This design retained the basic configuration and dimensions of the original actuator. Changes were made primarily to the cradle and motor assembly. Because of the increased dimensions of the thermal motor, it was necessary to increase the diameter of the pellet case and associated parts including the back off spring and the piston return spring. The new springs were designed to yield the same spring rate differential as the originals. The design effort resulted in a new top assembly and approximately twenty sub-assembly and detail drawings. A list of drawings generated by EMR is attached.

Source record↗
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.

Source record↗
NASA NTRS1975

The deep space network

The objectives, functions, and organization of the Deep Space Network are summarized along with deep space station, ground communication, and network operations control capabilities. Mission support of ongoing planetary/interplanetary flight projects is discussed with emphasis on Viking orbiter radio frequency compatibility tests, the Pioneer Venus orbiter mission, and Helios-1 mission status and operations. Progress is also reported in tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations.

Source record↗
NASA NTRS1974

A model for sequential decoding overflow due to a noisy carrier reference

An approximate analysis of the effect of a noisy carrier reference on the performance of sequential decoding is presented. The analysis uses previously developed techniques for evaluating noisy reference performance for medium-rate uncoded communications adapted to sequential decoding for data rates of 8 to 2048 bits/s. In estimating the ten to the minus fourth power deletion probability thresholds for Helios, the model agrees with experimental data to within the experimental tolerances. The computational problem involved in sequential decoding, carrier loop effects, the main characteristics of the medium-rate model, modeled decoding performance, and perspectives on future work are discussed.

Layland, J. W.↗
NASA NTRS1974

The international age in space

International cooperation in space programs is discussed. Early international efforts, such as the establishment of tracking station networks and utilization of communications and weather satellites, are outlined, and the Apollo-Soyuz Test Project and the Spacelab-Shuttle project are cited as major cooperative ventures. The ATS-6, Helios, and ERTS projects - which demonstrate the importance of international ties to the space program - are detailed.

Frutkin, A. W.↗
NASA NTRS1975

Leak rate measurements for satellite subsystems and residual gas analysis during space environment tests

The measuring and evaluation procedure for the determination of leak rates of satellite subsystems with a quadrupole mass spectrometer, and the results of the residual gas analysis are described. The method selected for leak rate determination was placing the system into a vacuum chamber and furnishing the chamber with a mass spectrometer and calibrated leaks. The residual gas of a thermal vacuum test facility, in which the thermal balance test radiation input was simulated by a heated canister, was analyzed with the mass spectrometer in the atomic mass unit range up to 300 amu. In addition to the measurements during the space environment tests, mass spectrometric studies were performed with samples of spacecraft materials. The studies were carried out during tests for the projects HELIOS, AEROS B and SYMPHONIE.

Nuss, H. E.↗
NASA NTRS1975

Current cosmic-ray programs in the United States

Approved NASA cosmic ray programs for the next five years are reviewed. In deep space, four new missions are planned. The first two, Helios A and B, will go inwards to approximately 0.3 AU, and the second two, Mariner Jupiter-Saturn, will go outwards to Saturn at 9.5 AU. Two missions in the earth orbital program promise to provide major new information on cosmic ray isotopes and on very heavy cosmic rays. These are the C mission of the International Sun-Earth Explorer, and the C mission of the High Energy Astronomy Observatory. The balloon research program is also mentioned.

Opp, A. G.↗
NASA NTRS1975

Analysis and prediction of Doppler noise during solar conjunctions

The results of a study of Doppler data noise during solar conjunctions were presented. During the first half of 1975, a sizeable data base of Doppler data noise (estimates) for the Pioneer 10, Pioneer 11, and Helios 1 solar conjunctions was accumulated. To analyze this data, certain physical assumptions are made, leading to the development of a geometric parameter ("ISI") which correlates strongly with Doppler data noise under varying sun-earth-spacecraft geometries. Doppler noise models are then constructed from this parameter, resulting in the newfound ability to predict Doppler data noise during solar conjunctions, and hence to additionally be in a position to validate Doppler data acquired during solar conjunctions.

Berman, A. L.↗
NASA NTRS1975

Centaur Standard Shroud (CSS) Heated Altitude Jettison Tests

Altitude jettison tests, at a pressure of 20 torr (0.39 psia), were performed on the Centaur Standard Shroud (CSS) in a 100-foot diameter vacuum chamber. These jettison tests were part of a series of flight qualification tests which were performed on the new CSS system in preparation for the Helios and Viking missions. The first two tests subjected the CSS to a thermal cycle which simulated aerodynamic heating during ascent flight and the third test was performed at altitude pressure and in ambient temperature conditions. The purpose of the ambient temperature test was to provide base line data by which the separate machanical and thermal factors that influence jettison performance could be evaluated individually. The CSS was successfully jettisoned in each of the three tests. Also, thermal, stress, and structural deflection data were obtained which verified the analytical predictions of CSS response to flight environmental conditions and performance during jettison. In addition, much important information was obtained on critical CSS-to-payload clearance losses due to shell motions prior to and during jettison. The effectiveness of the separation system was successfully demonstrated at maximum flight temperatures.

Source record↗
NASA NTRS1976

Doppler noise considered as a function of the signal path integration of electron density

The hypothesis is advanced that observed Doppler noise during solar conjunctions is proportional to total columnar electron content along the signal path. This assumption leads directly to a geometrical model (ISED) for observed Doppler noise which is shown to be in very good agreement with Doppler noise data accumulated during the 1975 Pioneer 10, Pioneer 11 and Helios 1 solar conjunctions. An augmented model is constructed which quantitatively indicates correlation between earth observed sunspot activity and systematic, cyclical deviations from the ISED model.

Berman, A. L.↗
NASA NTRS1976

Use of load and go countdowns by the DSN deep space stations

The Level-4 Prepass Readiness Test (PRT) (the load and go countdown) provides an effective and low risk method of improving network productivity. A carefully controlled trial period preceded the full-scale application of the Level-4 PRTS to Pioneer, Helios, and Viking cruise tracking operations. Use of this load and go concept to count down a station brings about a substantial increase in the proportion of total station hours devoted to spacecraft tracking.

Hatch, J. T.↗
NASA NTRS1975

Modulation and diffusion theory of cosmic rays

Papers given on the modulation of galactic cosmic rays by the solar wind at the 14th International Cosmic Ray Conference are reviewed. Some of the topics treated in this review are Pioneer and Helios radial gradient measurement, heliolatitude effects in modulation models, diffusion (scattering) theory - including pitch angle diffusion diagrams - solar flare particle transport theory and cosmic ray fluctuations at neutron monitor energies.

Forman, M. A.↗
NASA NTRS1976

Solar flare effects on the zodiacal light

Results are reported for an observational and theoretical study of possible solar-flare effects on the zodiacal light. A seven-year search for flare-induced brightness variations in the light is described which discovered no significant changes in either the level of brightness from night to night or the shape of the main zodiacal-light cone at elongations greater than 25 deg from the sun. Several possible dynamical effects of solar flares on the zodiacal dust cloud are investigated theoretically, including increased ion drag from a passing shock wave, possible rotational bursting of dust particles as a result of ion impacts, and fluorescence of the dust particles. It is found that the kinetic energy carried by shock-front ions is not sufficient to cause the dust to fluoresce, that increased ion drag may be significant only at heliocentric distances less than 0.1 AU, and that particles larger than 10 microns cannot attain bursting speeds at the appropriate distances. The question is considered of whether changes in the brightness of the polarized component as a result of variations in electron number density can be observed from earth or the Helios solar probe.

Misconi, N. Y.↗