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Uphoff, C. W.

Publications and source records attributed to Uphoff, C. W..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Characteristics of a dual mission concept for intensive study of moon and Mars or moon and asteroids

An assessment is presented of the results of recent feasibility studies on a low cost dual mission concept, employing a single spacecraft for the sequential, intensive survey of two planets. After establishing the features of a basic lunar-Martian polar orbiting mission in the context of existing spacecraft and propulsion technology, an examination of trajectory options shows that an earth return maneuver allows the application of the same concept to lunar-asteroid missions and offers substantial savings for the lunar-Martian mission. The implications of Centaur availability for extension of this concept to main-belt asteroids and to tripple missions are considered, along with questions of cost and reliability.

Uphoff, C. W.↗
NASA NTRS1982

Autonomous oxygen production for a Mars return vehicle

The way in which a chemical processor that uses the Martian atmosphere as its only feedstock, thereby reducing the mass that must be launched from earth, can help to return a surface sample from Mars from a single Space Shuttle launch is described. Richter's (1981) study on both the theoretical and experimental aspects of oxygen separation using yttria-stabilized zirconia membranes is cited. Here, separation is accomplished by applying a voltage across the membrane which results in the selective conduction of oxygen ions from one side to the other. It is noted that by using thermal dissociation of the carbon dioxide in the Martian atmosphere to produce oxygen (and carbon monoxide), these zirconia electrolytic cells can be employed to separate oxygen from the atmospheric stream. Descriptions are also given of atmospheric filtration, atmospheric compression, and waste heat recovery, and of the oxygen precooler and oxygen compressor.

Ash, R. L.↗
NASA NTRS1979

Aerobraking for planetary missions

This paper is a description of recent work to establish the feasibility of aerobraking for planetary orbit missions. Primary emphasis is on a close (300 km) Venus orbiter in 1984. Performance advantages for close Mars orbiters and geosynchronous round trip missions are also shown. A description of the aerobraking operations scenario is given and encouraging preliminary results of an orbit determination analysis are cited. A spacecraft design is presented that features a forward aeroshield and a 9-meter aft aerobrake of 2 mil Inconel. It is shown that, with relatively minor modifications the current Venus Orbital Imaging Radar (VOIR) mission spacecraft design can be adapted to aerobraking and that the aerobraking concept enables the VOIR mission in the difficult 1986 and 1988 opportunities.

French, J. R.↗
NASA NTRS1973

Parameter estimation supplement to the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)

This Parameter Estimation Supplement describes the PEST computer program and gives instructions for its use in determination of lunar gravitation field coefficients. PEST was developed for use in the RAE-B lunar orbiting mission as a means of lunar field recovery. The observations processed by PEST are short-arc osculating orbital elements. These observations are the end product of an orbit determination process obtained with another program. PEST's end product it a set of harmonic coefficients to be used in long-term prediction of the lunar orbit. PEST employs some novel techniques in its estimation process, notably a square batch estimator and linear variational equations in the orbital elements (both osculating and mean) for measurement sensitivities. The program's capabilities are described, and operating instructions and input/output examples are given. PEST utilizes MAESTRO routines for its trajectory propagation. PEST's program structure and subroutines which are not common to MAESTRO are described. Some of the theoretical background information for the estimation process, and a derivation of linear variational equations for the Method 7 elements are included.

Bjorkman, W. S.↗