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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Information extraction from digital images of the earth and the planets

An overview is presented of recent developments at the JPL Image Processing Laboratory which emphasize the utilization of a digital computer to automate the process of information extraction from digital imagery. Consideration is given to: (1) the analysis of Viking Orbiter stereo imagery to determine elevation profiles of the Mars surface, (2) the use of Viking Lander stereo imagery to determine nonhazardous surface sample acquisition strategies, (3) the correlation of Landsat imagery with geographically referenced cultural data to determine land use trends, and (4) the generation of mosaics using digital computer techniques.

Green, W. B.↗
NASA NTRS1979

Pseudocraters on Mars

In the Cydonia region of southern Acidalium Planitia are small, low-relief, apparently volcanic domelike structures, whose size, morphology, and general occurrence suggest they are martian analogs of terrestrial pseudocraters, a type of phreatic eruption. Average base diameters are about 800 m, which is somewhat larger than typical Icelandic examples. All the domes have summit pits; elongate domes generally have elongate summit pits or, in extreme cases, double pits. The greatest concentration of these domes is in a region of subdued fractured plains which may be old volcanic flows. Pseudocraters on the earth are produced when lava flows over water-logged ground. On Mars surface or subsurface ice was the likley medium that produced the steam eruptions resulting in cratered domelike structures on the lava surfaces.

Frey, H.↗
NASA NTRS1981

Analysis of data from Viking RPA's

Measurements of the martian ionosphere performed by Viking Retarding Potential Analyzer (RPA) are reported. Viking RPA measurements of low energy electron fluxes out to 16,000 km above the Mars surface are discussed including both energy spectra and periods of continuous monitoring of the total flux above 15 ev. The mean electron current at energies greater than ev increases montonically by nearly two orders of magnitude from about 9000 km down to 700 km, but no clear signature of the bow shock is seen. The total wave power in the 2 sec measurement intervals for this current does, however, show a broad peak near 1700 km altitude. These variations in the low energy electron fluxes are related to whistler mode oscillations in the solar wind plasma. It is concluded that there may be a highly turbulent shock structure that masks a clear signature of the bow shock in the time averaged data.

Hanson, W. B.↗
NASA NTRS1981

Third International Colloquium on Mars

Abstracts of papers concerning the geology and geophysics of Mars, volcanism on Mars, the Mars atmosphere, and the long term history of the atmosphere-cap-regolith volatile regime are presented. Formation of the Mars surface, climatology, gravity and magnetism, atmospheric boundary layers, and interpretation of Viking imagery and Earth-based observations are considered.

Source record↗
NASA NTRS1982

The solar wind interaction with Mars as seen by the Viking retarding potential analyzers

Both energy spectra and continuous monitoring periods of the total flux above 15 eV are available, from Viking retarding potential analyzer measurements of electron fluxes not exceeding 75 eV out to 16,000 km above the Mars surface. Although the mean electron current at energies above 15 eV increases monotonically by almost two orders of magnitude from 9000 to 700 km in Viking 1 data, no clear signature of the bow shock is seen. Total current wave power shows a peak near 1700 km altitude. It is suggested that there may be a highly turbulent shock structure masking a clear signature of the bow shock in the time-averaged data, and it is concluded that the interaction model consistent with the bow shock at 1700 km, together with ionosphere measurements, indicates a permanent magnetic field able to stand off the solar wind during the Viking 1 entry.

Cragin, B. L.↗
NASA NTRS1983

A proposed new policy for planetary protection

A policy on the protection of extraterrestrial bodies from contamination by terrestrial microorganisms and organic constituents that might interfere with studies of chemical and biological evolution on those bodies is proposed which is based on new information gained in planetary exploration over the past decade. The proposed policy overcomes the difficulties associated with the uncertainties in parameters and the rigid requirements of the current probabilistic approach by eliminating the general quantitative guideline and by calling for the implementation of planetary protection procedures for space projects by exception, depending on target planet and type of encounter. The impact of the proposed policy on the implementation of future space missions is illustrated for the Galileo Jupiter mission, a cometary mission, the Saturn Orbiter with Twin Probes, and a Mars Surface Sample Return Mission, and procedures which may lead to the eventual adoption of the policy are noted.

Devincenzi, D. L.↗
NASA NTRS1984

Activities at the Lunar and Planetary Institute

The scientific and administrative activities of the Lunar and Planetary Institute are summarized. Recent research relating to geophysics, planetary geology, the origin of the Earth and Moon, the lunar surface, Mars, meteorites, and image processing techniques is discussed.

Burke, K.↗
NASA NTRS1984

The Planetary Observer Program

An overview is presented of NASA's plans for the Planetary Observer Program, whose key element is to control the cost of each mission while establishing a long-term, stable base for the planetary sciences. The SSEC (Solar System Exploration Committee) has endorsed the view that many high science priority inner solar system missions are possible through the use of spacecraft derived from existing earth-orbital spacecraft. It has also recommended the application of space hardware such as that used on the Voyager and Galileo missions, development of both a new modular spacecraft for outer planet, comet, and main-belt asteroid missions (Mariner Mark II Program), and a multi-mission operations system to support future missions after the Venus Radar Mapper (VRM), and Galileo. A set of missions for the SSEC's Core Program has been recommended; they include: the VRM, the Mars Geoscience/Climatology Observer, the Comet Rendezvous/Asteroid Flyby, the Lunar Geoscience Orbiter, the Near-Earth Asteroid Rendezvous, the Venus Atmosphere Probe, the Mars Aeronomy Orbiter, the Mars Surface Probe, and the Comet Intercept Sample Return.

Blume, W. H.↗
NASA NTRS1986

Global duricrust on Mars - Analysis of remote-sensing data

A study is conducted of the infrared thermal emission, radio thermal emission, and radar reflection data sets with the objective to obtain a simple and self-consistent model for the Mars surface. The results are compared with in situ observations at the Viking Lander sites. Attention is given to thermal inertia values, the abundance of surface rocks, radar/thermal correlations, diurnal temperature deviations, and radio emission data. It is suggested that all of the global remote-sensing data sets considered can be reconciled on the basis of variations in the degree of formation of a case-hardened crust or duricrust. On the other hand, no other model which has been proposed in conjunction with any individual data set can satisfy all of the constraints discussed.

Jakosky, B. M.↗
NASA NTRS1986

Comment on the paper 'On the influx of small comets into the earth's upper atmosphere. II - Interpretation' by L. A. Frank, J. B. Sigwarth and J. D. Craven

The proposal by Frank et al. (1986) that clouds of small comets periodically inject large amounts of H2O into the upper atmospheres of the earth, Venus, and Mars is examined critically, with a focus on transport and disposal mechanisms invoked to account for the large H2O masses involved. It is argued that observed parameter values (such as mixing ratios, vertical wind velocities, and H escape flows) prohibit transport by eddy, molecular diffusion, vertical avection, or coherent movement. In a reply by Frank et al., these objections are discussed in terms of an overall description of the decelerataion and penetration of a cometary water cloud, and H2O concentrations and mixing mechanisms consistent with observed values for the earth are proposed. It is suggested that an increase in cometary H2O influx could lead to concentrations attaining the frost point and to formation of a global mesospheric cloud with significant climate effects. A lower H2O influx rate for Venus (consistent with observed H loss and atmospheric H2O concentration) and relatively rapid loading of the Mars surface and atmosphere with H2O ice and vapor (followed by brief warming periods with increased exospheric H2O outflow and surface flow of liquid H2O) are considered.

Donahue, T. M.↗
NASA NTRS1986

Aerobraking

This paper presents a discussion of the basic principles of aerobraking. Typical results are given for the application of aerobraking to orbital capture at Mars, descent to the Mars surface and orbital capture on return to Earth.

V A Dauro↗
NASA NTRS1986

Mars base buildup scenarios

Two Mars surface based build-up scenarios are presented in order to help visualize the mission and to serve as a basis for trade studies. In the first scenario, direct manned landings on the Martian surface occur early in the missions and scientific investigation is the main driver and rationale. In the second senario, Earth development of an infrastructure to exploit the volatile resources of the Martian moons for economic purposes is emphasized. Scientific exploration of the surface is delayed at first in this scenario relative to the first, but once begun develops rapidly, aided by the presence of a permanently manned orbital station.

J D Blacic↗
NASA NTRS1986

Mission and space vehicle concepts

This paper discusses a number of top-level considerations which affect Mars and vehicle selection. Indications are provided of the nature and severity of the impact of these considerations on missions and vehicles. The paper identifies and discusses various types of missions, such as Mars fly-bys, Mars orbiting and landing missions, and missions to the moons of Mars. Mission trajectories and opportunities are discussed briefly. The paper also discusses the different types of vehicles required in a Mars program. Discussion includes several potential Earth-to-Orbit (ETO) vehicles, Mars surface vehicles, and 2 types of Orbit-to-Orbit (OTO) vehicles. Indications are provided as to preference for some of the concepts discussed.

John Butler↗
NASA NTRS1986

Manned Mars missions: A working group report

The discussions of the Working Group (based in large part on working papers, which will shortly be published separately) are summarized. These papers cover a broad range of subjects which need to be addressed in the formulation of such a formidable enterprise as a manned Mars program. Science objective and operations; Mars surface infrastructure and activities; mission and system concepts and configurations; life sciences; impacts on the space infrastructure; and costs, schedules, and organizations are addressed.

Duke, Michael B.↗
NASA NTRS1987

Some probable characteristics of the Martian regolith

A number of Mars surface environmental factors seriously affect the properties of the Martian regolith. The result is a regolith that is rather different from that of the moon. Some of the anticipated differences are discussed: weathering and lack of old glass; desert varnish; lack of micrometeorite impact products; abundance of meteorite fragments; and different grain size characteristics.

King, Elbert A.↗
NASA NTRS1988

Aerospace vehicle design, spacecraft section. Volume 1

The objective was to create a manned Martian aircraft which can perform: scientific surveys of particular sites distant from the base; a deployment of scientific instrument packages by air drop that land rovers cannot accomplish; and rescue operations. Designing the airfoil requires a wing which can operate within the low Reynolds numbers apparent on Mars. The airfoil, NASA NLF(1)-1015 was chosen. The design of the aircraft is comparable to a P-38 military aircraft. The aircraft uses fuel cells to power the two propellers. A rocket-assisted takeoff is necessary to enable Romulus to liftoff. Although the design and creation of Romulus would be an expensive adventure, such a vehicle could be most useful in evaluating the Mars surface and in creating a habitat for mankind.

Source record↗
NASA NTRS1988

Extravehicular activity at geosynchronous earth orbit

The basic contract to define the system requirements to support the Advanced Extravehicular Activity (EVA) has three phases: EVA in geosynchronous Earth orbit; EVA in lunar base operations; and EVA in manned Mars surface exploration. The three key areas to be addressed in each phase are: environmental/biomedical requirements; crew and mission requirements; and hardware requirements. The structure of the technical tasks closely follows the structure of the Advanced EVA studies for the Space Station completed in 1986.

Shields, Nicholas, Jr.↗
NASA NTRS1987

Expert system isssues in automated, autonomous space vehicle rendezvous

The problems involved in automated autonomous rendezvous are briefly reviewed, and the Rendezvous Expert (RENEX) expert system is discussed with reference to its goals, approach used, and knowledge structure and contents. RENEX has been developed to support streamlining operations for the Space Shuttle and Space Station program and to aid definition of mission requirements for the autonomous portions of rendezvous for the Mars Surface Sample Return and Comet Nucleus Sample return unmanned missions. The experience with REMEX to date and recommendations for further development are presented.

Goodwin, Mary Ann↗