Strategy for Space Science and Technology
Historic changes have occurred in the world in the past few years. Partnerships between Government and industry are viewed as a catalyst for this process.
integrated↗
Engineering topics
Varsi, G.
Publications and source records attributed to Varsi, G..
Technology Plan for the Exploration of the Solar System
Explore the source record for details and available documents.
Integrated Technology Strategy NASA testbeads tech↗
Solar System Exploration, 1995-2000
Goals for planetary exploration during the next decade include: (1) determine how our solar system formed, and understand whether planetary systems are a common phenomenon through out the cosmos; (2) explore the diverse changes that planets have undergone throughout their history and that take place at present, including those that distinguish Earth as a planet; (3) understand how life might have formed on Earth, whether life began anywhere else in the solar system, and whether life (including intelligent beings) might be a common cosmic phenomenon; (4) discover and investigate natural phenomena that occur under conditions not realizable in laboratories; (5) discover and inventory resources in the solar system that could be used by human civilizations in the future; and (6) make the solar system a part of the human experience in the same way that Earth is, and hence lay the groundwork for human expansion into the solar system in the coming century. The plan for solar system exploration is motivated by these goals as well as the following principle: The solar system exploration program will conduct flight programs and supporting data analysis and scientific research commensurate with United States leadership in space exploration. These programs and research must be of the highest scientific merit, they must be responsive to public excitement regarding planetary exploration, and they must contribute to larger national goals in technology and education. The result will be new information, which is accessible to the public, creates new knowledge, and stimulates programs of education to increase the base of scientific knowledge in the general public.
Squyres, S.↗
Mars Microrover For Mesur Pathfinder
The advent of spacecraft miniaturization promises a new generation of affordable planetary missions; they will be more cost effective - by one to two orders of magniture - than those of traditional design.
Mars↗
Space Station as a vital focus for advancing the technologies of automation and robotics
The application of robotics and automation technologies to the Space Station design is examined. Experiments being conducted in the fields of autonomy and robotics, and the benefits provided by these technologies are discussed. The use of automation and robotics in the operation management, the power system, and telerobot of the Space Station is described.
Varsi, G.↗
Automation of planetary spacecraft
The development of autonomous spacecraft from 1960 to the present is traced within a framework of the definitions and measures of the level of autonomy. The attainment of milestones in the level of autonomy in spacecraft guidance and control is described in terms of the Mariner, Viking, Voyager, Galileo and Mark II (under development) spacecraft. The constant interplay between the definition of scientific mission goals and available technological capabilities is explored, along with current efforts to implement AI techniques and advanced software in spacecraft to allow reliable functioning in stressful conditions.
Varsi, G.↗
Detonation propulsion experiments and theory
Previously cited in issue 17, p. 2705, Accession no. A82-35015
Back, L. H.↗
Detonation propulsion experiments and theory
Test data are presented for the use of a single detonation of explosives in long-cone, short-cone, straight, and firing-plug nozzles to provide propulsion in a simulated Jupiter atmosphere, as well as the ambient gases N, CO2 and He. The long-cone nozzle yielded a progressive increase with ambient pressure for the higher molecular weight gases CO2 and N, while the lower molecular weight He and simulated Jupiter atmosphere showed a specific pulse decrease with increasing ambient pressure. The short-plug nozzle yielded a small specific impulse reduction with increasing ambient pressure, and its results were found to be nearly independent of ambient gas molecular weight. All data gathered are analyzed by using first principles, approximate blast wave theory predictions, and two-dimensional numerical calculations. Rarefaction and oscillatory wave phenomena are found to significantly influence specific impulse.
Back, L. H.↗
Characterization of the exhaust particulates in the ground cloud and high-altitude plume of large solid-propellant booster rockets
The report is concerned with the characterization of Al2O3 particles in the atmosphere. These particles comprise one of the major combustion products of the rocket propellant employed in the Space Shuttle boosters. A ground cloud and stratospheric plume are considered. It is concluded that the typical residence times in the atmosphere are much longer than earlier estimates have indicated.
Strand, L. D.↗
Instrument for aerosol characterization
Differential pumping system that directs particles into beam moving at high speed measures size distribution and chemical composition of aerosols and is useful in study of atmospheric contamination, smog, stack gases, and chemical aerosols.
Varsi, G.↗
Seismic vibration source
A system for vibrating the earth in a location where seismic mapping is to take place is described. A relatively shallow hole formed in the earth, such as a hole 10 feet deep, placing a solid propellant in the hole, sealing a portion of the hole above the solid propellant with a device that can rapidly open and close to allow a repeatedly interrupted escape of gas. The propellant is ignited so that high pressure gas is created which escapes in pulses to vibrate the earth.
Dowler, W. L.↗
Feasibility of rocket propellant production on Mars
In situ production of rocket propellant to reduce landed mass requirements for Mars return missions has been investigated. The analysis has shown that a system which utilizes atmospheric carbon dioxide and soil moisture to produce liquid methane-oxygen propellant requires a landed mass which is less than half the mass of the ascent vehicle it produces.
Ash, R. L.↗
Solar sailing - The concept made realistic
The practicability of using solar sails as a means of spacecraft propulsion is discussed with reference to a Haley's comet rendezvous mission in 1981. Two types of sails are examined: square and heliogyro. Because of ease of deployment (release into space from a space shuttle, and unfolding of the blades through solar radiation pressure) the latter is preferred. Structural and mission parameters are given for the heliogyro configuration, with attention to operational temperature limits and material coefficients. A cranking orbit is described, where a sail-powered spacecraft flies first toward the sun, and then away from it in order to achieve rendezvous with a comet. Other missions using solar sails, including a back-up mission to Encke's comet in 1983, are also discussed.
Friedman, L.↗
Computer measurement of particle sizes in electron microscope images
Computer image processing techniques have been applied to particle counting and sizing in electron microscope images. Distributions of particle sizes were computed for several images and compared to manually computed distributions. The results of these experiments indicate that automatic particle counting within a reasonable error and computer processing time is feasible. The significance of the results is that the tedious task of manually counting a large number of particles can be eliminated while still providing the scientist with accurate results.
Hall, E. L.↗
Blast wave in a nozzle for propulsive applications
The reported investigation has been conducted in connection with studies concerning the development of a propulsion system based on the use of a detonating fluid propellant. Measurements have been made of the pressure and shock wave velocity in a conical nozzle at various ambient pressures and at an ambient temperature of 25 C. In the experiments a small amount of explosive was placed at the end wall of a conical aluminum nozzle and detonated by a microdetonator inside the nozzle. Differences regarding the characteristics of conventional chemical propulsion and detonation propulsion are illustrated with the aid of a graph. One- and two-dimensional numerical flow calculations were performed and compared with the experimental data.
Varsi, G.↗
Measurements and calculations of detonation propulsion performance in helium
Previously obtained results are extended to helium ambient gas to help in the assessment of performance in the atmospheres of the major planets. Measurements confirm benefits derived form detonating propellant over conventional chemical rocket propulsion. Benefits however, are reduced at high pressures in low molecular weight gas. Numerical calculations by means of a monodimensional hydrodynamic code follow the different trends obtained experimentally for high and low molecular weight gas and also offer new insights on the time behavior of the process.
Kim, K.↗
Explosive propulsion applications
The feasibility and application of an explosive propulsion concept capable of supporting future unmanned missions in the post-1980 era were examined and recommendations made for advanced technology development tasks. The Venus large lander mission was selected as the first in which the explosive propulsion concept can find application. A conceptual design was generated and its performance, weight, costs, and interaction effects determined. Comparisons were made with conventional propulsion alternatives. The feasibility of the explosive propulsion system was verified for planetology experiments within the dense atmosphere of Venus as well as the outer planets. Additionally, it was determined that the Venus large lander mission could be augmented ballistically with a significant delivery margin.
Nakamura, Y.↗
Effect of fast neutron, gamma-ray and combined radiations on the thermal decomposition of ammonium perchlorate single crystals
The thermal decomposition kinetics have been determined for ammonium perchlorate crystals subjected to a fast neutron irradiation or to a fast neutron irradiation followed by a gamma-ray irradiation. Qualitatively, the radiation induced changes are similar to those obtained in this and in previous studies, with samples exposed only to gamma rays. The induction period is shortened and the rate constants, obtained from an Avrami-Erofeyev kinetic analysis, are modified. The acceleratory period constant increases and the decay period constant decreases. When compared on an equal deposited energy basis, the fast neutron induced changes are appreciably larger than the gamma-ray induced changes. Some, or all, of the fast neutron induced effects might be attributable to the introduction of localized regions of concentrated radiation damage ('spikes') by lattice atom recoils which become thermal decomposition sites when the crystals are heated.
Herley, P. J.↗