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At least 667 records · Page 37

Report of the Terrestrial Bodies Science Working Group. Volume 2: Mercury

The objectives and rationale for scientific investigation of Mercury are explored. Knowledge already obtained by astronomical observations and Mariner 10 spacecraft is reviewed and measurements required for the principal scientific goals are described. The use of low thrust propulsion systems is recommended so that maximum scientific return may be achieved and the reconnaissance phase of Mercury exploration may be completed in a single mission. Accelerated development is recommended on solar electric propulsion, solar sails, passive and active cooling mechanisms, and single rough landers.

Albee, A. L.↗

The future impact of computation on planetary exploration

Informed speculations are advanced on plausible candidates for space exploration missions in decades ahead; while none are approved NASA projects, they are deemed accessible to current technology. A Venus radar mapper, a minirover system (several rovers) for Mars surface exploration (geology, areochemistry, meteorology, detection of biota), investigation of Halley's comet (1986 apparition) with the aid of a solar sail vehicle, flybys of Jovian (Galilean) satellites and a landing on Ganymede, and a soft landing on the Saturnian large satellite Titan for examination of its atmosphere and surface are sketched. Anticipated data rates, software, mission reliability, and spacecraft autonomy are discussed, along with anticipated improvements in information transmission hardware and software, and some conjectures beyond the turn of the century.

Whitney, W. M.↗

Flight to Mercury

The project development and active flight of the Mariner 10 deep-space probe mission is recounted in detail, with sequential blow-by-blow coverage. Early studies and speculation on the planet Mercury are reviewed, and the spin-orbit coupling and near-synchronous rotation of the planet are described. Use of Venus as a slingshot in a gravity-assist maneuver is described, and Mariner 10 records of Venus are shown. The three encounters of Mariner 10 with Mercury (March 1974, Aug. 1974, March 1975) are described in detail, with purposes, problems, mishaps, and glossy photographs recovered from Mariner 10 data. Information on the planet's magnetosphere, surface topography, inferred internal structure, and IR signature is provided, and the end-of-mission improvised solar-sail experiment is outlined.

Murray, B.↗

Effects of space radiation on thin polymers and nonmetallics

Advanced materials for various spacecraft systems in the 1980s and 1990s have been evaluated in situ after exposure to space radiation. Emphasis has been placed on materials having little or no previous base of environmental effects data. Applications ranging from earth orbit to near-sun have been covered. High temperature polymers and composites have been included. Silica composites may offer improved reflectance stability compared with metallized fluorocarbons. Directional reflectance properties of FEP are a function of charged particle energy and flux as well as total exposure fluence and material characteristics. Data obtained on polyimides and polyxylylenes under high temperature radiation exposure conditions will be discussed in the context of near-sun solar sailing and rendezvousing.

Fogdall, L. B.↗

Independent Evaluation of Shuttle Flight Control System

A brief summary of the work performed on the Approach and Landing Test (ALT) shuttle flight control system is presented. (FCS) and a bibliography of the formal reports are included which document the activities in detail. In general, the activities were grouped in four categories: (1) independent evaluation of ALT FCS software design; (2) independent evaluation of Software Development Laboratory (SDL) testing of ALT FCS software; (3) independent evaluation of Shuttle Avionics Integration Laboratory (SAIL) ALT FCS testing; and (4) independent evaluation of ALT flight test results.

Lee, R.↗

Future thrusts in the U.S. planetary program

The aim of the U.S. deep space program concept is to complete the reconnaissance of the solar system and to transfer to the era of space utilization. Such spacecraft as the Voyager Jupiter-Saturn and the Pioneer Venus will be used to visit all the planets and smaller bodies of the solar system by the year 2000. In the present paper, some missions, still in the early planning stage and requiring Congressional approval are discussed, and the enormous capabilities of Solar Electric Propulsion (SEP) and Solar Sailing are pointed out. The advantages of such low-thrust propulsion systems in performance, mission design, and operations flexibility are noted.

Friedman, L. D.↗

Satellite mirror systems for providing terrestrial power - System concept

A system of orbiting reflectors, SOLARES, has been studied as a possible means of providing terrestrial power with a space system of minimum mass and complexity. The key impact that such a system, providing continuous and slightly concentrated insolation, makes on the economic viability of solar farming is demonstrated. New developments in solar sailing are incorporated to reduce mirror mass and transportation cost. The system is compatible with incremental implementation and continual expansion to produce the world's power needs. Key technology, environmental, and economic issues and payoffs are identified. SOLARES appears to be economically superior to other advanced, and even conventional, energy systems and could be scaled to completely abate our fossil fuel usage for power generation.

Billman, K. W.↗

Large structure control development concepts

Viewpoints are presented on large structure control evolving from the solar sail study conducted at JPL. The objective is to make optimum use of insights gained in the study in order to assess required large structure control developments.

Rodriguez, G.↗

Mercury orbiter transport study

A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

Friedlander, A. L.↗

Advanced planetary studies

Eleven study tasks are described and key results are discussed for the following: advanced planning activity; cost estimation research; planetary missions performance handbooks-revisions; multiple discipline science assessment; asteroid workshop; galilean lander mission strategies; asteroid exploration study; ion drive transport capabilities; Mars strategy study; Venus surface sample return; and ion drive/solar sail assessment study.

Source record↗

Study of Membrane Reflector Technology

Very large reflective surfaces are required by future spacecraft for such purposes as solar energy collection, antenna surfaces, thermal control, attitude and orbit control with solar pressure, and solar sailing. The performance benefits in large membrane reflector systems, which may be derived from an advancement of this film and related structures technology, are identified and qualified. The results of the study are reported and summarized. Detailed technical discussions of various aspects of the study are included in several separate technical notes which are referenced.

Knapp, K.↗

Advanced composites - Future space applications

Potential applications of composite materials in kilometer-size space systems are reviewed noting the advent of the NASA Space Transportation System. Antenna configurations are considered with reference to the 10-m-diam wrapped-rib antenna used on the ATS-6 satellite, a 15-m-diam graphite/epoxy wrapped-rib antenna, and a folding planar array synthetic aperture radar antenna. The heliogyro solar sail concept is presented along with solar power station designs based on either photovoltaic arrays or parabolic arrays of flat facets. The development of beam fabricators is described.

Boundy, R. A.↗

Strong thin membrane structure

A continuous process is described for producing strong lightweight structures for use as solar sails for spacecraft propulsion by radiation pressure. A thin reflective coating, such as aluminum, is applied to a rotating cylinder. A nylon mesh, applied over the aluminum coating, is then coated with a polymerizing material such as a para-xylylene monomer gas to polymerize as a film bound to the mesh and the aluminum. An emissivity increasing material such as chromium or silicon monoxide is applied to the polymer film to disperse such material colloidally into the growing polymer film, or to the final polymer film. The resulting membrane structure is then removed from the cylinder. Alternately, the membrane structure can be formed by etching a substrate in the form of an organic film such as a polymide, or a metal foil, to remove material from the substrate and reduce its thickness. A thin reflective coating (aluminum) is applied on one side of the substrate, and an emissivity increasing coating is applied on the reverse side of the substrate.

Frazer, R. E.↗

A prelude to interstellar flight

A 20 to 50 year interstellar precursor mission extending 400 to 1000 AU from the solar system is outlined as a means of bringing out and solving engineering problems inherent in a star mission, and of studying the heliopause, the interstellar medium, and cosmic rays outside the heliosphere. Solar or laser sailing combined with a 500 kWe nuclear-electric propulsion system using fission would achieve a heliocentric excess velocity of 100km/s for the 32,000 kg spacecraft having a Shuttle derivative as a launch vehicle, and containing a Pluto flyby or separate orbiter powered by radioiosotope thermoelectric generators. X-band transmission using 40 w of power, a 15 m diameter spacecraft antenna and a 100 m receiving antenna on earth and providing 100 b/s is proposed, but a rate of 2 to 4 kb/s via 500 to 1000 w of power using the K-band and a 300 m diameter receiving antenna located on an Orbiting Deep Space Relay Station is also considered.

Jaffe, L. D.↗

Space manufacturing III; Proceedings of the Fourth Conference, Princeton University, Princeton, N.J., May 14-17, 1979

Papers are presented on the various technological, political, economic, environmental and social aspects of large manufacturing facilities in space. Specific topics include the potential global market for satellite solar power stations in 2025, the electrostatic separation of lunar soil, methods for extraterrestrial materials processing, the socio-political status of efforts toward the development of space manufacturing facilities, the financing of space industrialization, the optimization of space manufacturing systems, the design and project status of Mass Driver Two, and the use of laser-boosted lighter-than-air-vehicles as heavy-lift launch vehicles. Attention is also given to systems integration in the development of controlled ecological life support systems, the design of a space manufacturing facility to use lunar materials, high performance solar sails, the environmental effects of the satellite power system reference design, the guidance, trajectory and capture of lunar materials ejected from the moon by mass driver, the relative design merits of zero-gravity and one-gravity space environments, consciousness alteration in space and the prospecting and retrieval of asteroids.

Grey, J.↗

KU-Band rendezvous radar performance computer simulation model

The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation/radar simulation interface requirements, and the method selected to model target scattering properties, including an application of this method to the SPAS spacecraft are described. The radar search and acquisition mode performance model and the radar track mode signal processor model are examined and analyzed. The angle, angle rate, range, and range rate tracking loops are also discussed.

Griffin, J. W.↗

The effect of radiation pressure on the restricted three-body problem

The classical restricted three-body problem is extended to account for the effects of radiation pressure and the Poynting-Robertson effect on a particle with a surface-to-volume relation such that radiation pressure forces are nonnegligible moving in the gravitational field of two larger, orbiting bodies. The positions of the L4 and L5 Lagrangian points are found as functions of the ratio of radiational to gravitational forces. The inclusion of the Poynting-Robertson effect, however, is found to render the L4 and L5 points unstable on a time scale which is long compared to the rotation period of the two massive bodies. The results imply that space colonies with solar facing adjustable sails may be able to remain stationary at any heliocentric distance between a planet and the sun, and may provide a mechanism for producing asymmetries in the interplanetary dust cloud.

Schuerman, D. W.↗

Illumination from space with orbiting solar-reflector spacecraft

The feasibility of using orbiting mirrors to reflect sunlight to Earth for several illumination applications is studied. A constellation of sixteen 1 km solar reflector spacecraft in geosynchronous orbit can illuminate a region 333 km in diameter to 8 lux, which is brighter than most existing expressway lighting systems. This constellation can serve one region all night long or can provide illumination during mornings and evenings to five regions across the United States. Preliminary cost estimates indicate such an endeavor is economically feasible. The studies also explain how two solar reflectors can illuminate the in-orbit nighttime operations of Space Shuttle. An unfurlable, 1 km diameter solar reflector spacecraft design concept was derived. This spacecraft can be packaged in the Space, Shuttle, transported to low Earth orbit, unfurled, and solar sailed to operational orbits up to geosynchronous. The necessary technical studies and improvements in technology are described, and potential environmental concerns are discussed.

Canady, J. E., Jr.↗