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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Design and testing of the navigation model for three axis stabilized earth oriented satellites applied to the ATS-6 satellite image data base

An earth edge methodology has been developed to account for the relative attitude changes between successive ATS-6 images which allows reasonable high quality wind sets to be produced. The method consists of measuring the displacements of the right and left infrared earth edges between successive ATS-6 images as a function of scan line; from these measurements the attitude changes can be deduced and used to correct the apparent cloud displacement measurements. The wind data sets generated from ATS-6 using the earth-edge methodology were compared with those derived from the SMS-1 images (and model) covering the same time period. Quantitative comparisons for low level trade cumuli were made at interpolated uniformly spaced grid points and for selected individual comparison clouds. Selected individual comparison clouds, the root-mean-square differences for the U and V components were 1.0 and 1.2 meters per second with a maximum wind direction difference of 15 deg.

Kuhlow, W. W.↗
NASA NTRS1972

Orientation and resonance locks for satellites in the elliptic orbit.

In order to achieve the maximum strength of higher resonance locks for satellites in the elliptic orbit, the condition of satellite orientation during the process of deployment is established. It is shown that for maximum strength locks the axis of the minimum moment of inertia of satellites should point toward the attracting body at plus or minus (5/8) pi and 0 values of the true anomaly f. This condition of deployment is applicable to all cases of resonance rotation regardless of the value of lock number k and orbit eccentricity e.

Liu, H.-S.↗
NASA NTRS1977

Pine seed germination under weightlessness (a study of the Kosmos 782 satellite)

Orientation of the above and underground organs of pine plants, grown from seeds under weightlessness, was found to be determined by seed position on the substrate. Normal plant growth was observed only if the seed embryos were oriented toward the substrate. Some differences were noted between the experimental and control plants concerning the amount of nucleoli in the root meristematic cells and the cell shape in cotyledonous leaves. No complete similarity was found in experimental results obtained with plants under weightlessness and under compensated gravity. The seeds were obtained from Pinus silvestris, considered to be particularly suitable for this experiment.

Platonova, R. N.↗
NASA NTRS1980

Extravehicular Crewman Work System (ECWS) study program. Volume 3: Satellite service

The satellite service portion of the Extravehicular Crewman Work System Study defines requirements and service equipment concepts for performing satellite service from the space shuttle orbiter. Both normal and contingency orbital satellite service is required. Service oriented satellite design practices are required to provide on orbit satellite service capability for the wide variety of satellites at the subsystem level. Development of additional satellite service equipment is required. The existing space transportation system provides a limited capability for performing satellite service tasks in the shuttle payload bay area.

Wilde, R. C.↗
NASA NTRS1975

Cooling systems for satellite remote sensing instrumentation

The current and developing state-of-the-art in cryogenic coolers for satellite sensors was studied for earth oriented satellites. Six representative sensor categories in the 77 K to 300 K range were defined. Cooling capacities were 50 to 1000 mw; both continuous and intermittent duty cycles were considered; lifetimes were one to two years. Conceptual designs were prepared for the most promising coolers in each category. These coolers are Joule-Thomson, Solid Cryogen, Vuilleumier, Thermoelectric, Shielded Radiator, Optical Solar Reflector Radiator and Unshielded Radiator. Weight, envelope, power requirements and operating characteristics of each cooler are described. Scaling data for each cooler are included.

Copeland, R. J.↗
NASA NTRS1974

Performance of the SERT 2 spacecraft after 4 and one-half years in space

The SERT 2 satellite, launched in February, 1970, has recently been reactivated after being dormant for a year. The satellite orientation was changed to spin stabilization in 1973 and the satellite is now coning such that the active side of the solar arrays move into and out of the sun every 23 days. There is sufficient power to operate the ion thrusters for seven days of this cycle. The 2 ion thruster system was successfully operated; the electrical short in the accelerating grids had cleared during the year long dormant phase.

Ignaczak, L. R.↗
NASA NTRS1976

Investigation of environmental perturbations on passive asymmetric satellite

The effects of environmental perturbations on the attitude of a slow tumbling earth-oriented satellite are investigated. The environmental perturbations considered were aerodynamic drag, gravity-gradient, solar radiation pressure, and magnetic torques. The Euler attitude equations were solved numerically for the Skylab spacecraft. Results are presented for both torque-free motion and for cases in which aerodynamic and gravity-gradient torques are acting in a slow tumble mode. Simulations show gravity-gradient effects on satellite momentum to be cyclic and to increase the precession rate of the angular momentum vector about the radius vector. This also tends to align the minor axis along the radius vector. Aerodynamic drag initially decreases angular momentum, slowly precesses the momentum vector about the radius vector, and finally drives the satellite into an unstable mode. Combined gravity-gradient and aerodynamic torques reduce angular momentum and energy, and induce a steady precession rate of the momentum vector about the radius vector.

Tate, V.↗