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At least 469 records · Page 26

Pioneer project - 1965-1970

Pioneer spacecraft flight missions, discussing interplanetary, solar-earth and deep space observations

Dickerson, L. W.↗

An Implicit Finite Difference Solution to the Viscous Radiating Shock Layer with Strong Blowing

An implicit finite difference scheme is developed for the fully coupled solution of the viscous radiating stagnation line equations, including strong blowing. Solutions are presented for both air injection and carbon phenolic ablation products injection into air at conditions near the peak radiative heating point in an earth entry trajectory from interplanetary return missions. A detailed radiative transport code that accounts for the important radiative exchange processes for gaseous mixtures in local thermodynamic and chemical equilibrium is utilized.

Garrett, L. B.↗

An implicit finite-difference solution to the viscous shock layer, including the effects of radiation and strong blowing

An implicit finite-difference scheme is developed for the fully coupled solution of the viscous, radiating stagnation-streamline equations, including strong blowing. Solutions are presented for both air injection and injection of carbon-phenolic ablation products into air at conditions near the peak radiative heating point in an earth entry trajectory from interplanetary return missions. A detailed radiative-transport code that accounts for the important radiative exchange processes for gaseous mixtures in local thermodynamic and chemical equilibrium is utilized in the study. With minimum number of assumptions for the initially unknown parameters and profile distributions, convergent solutions to the full stagnation-line equations are rapidly obtained by a method of successive approximations. Damping of selected profiles is required to aid convergence of the solutions for massive blowing. It is shown that certain finite-difference approximations to the governing differential equations stabilize and improve the solutions. Detailed comparisons are made with the numerical results of previous investigations. Results of the present study indicate lower radiative heat fluxes at the wall for carbonphenolic ablation than previously predicted.

Garrett, L. B.↗

The pioneer projects: Economical exploration of the solar system

The interplanetary Pioneer missions are reviewed in terms of management implications and cost control. The responsibilities, organizational structure, and management practices of the Pioneer Projects are presented. The lines of authority and areas of responsibility of the principal organizational elements supporting the Pioneer missions are identified, and the methods employed for maintaining effective and timely interactions among these elements are indicated. The technical and administrative functions of the various organizational elements of the Pioneer Project Office at Ames Research Center are described in terms of their management responsibilities and interactions with other elements of the Project Office and with external organizations having Pioneer Project responsibilities. The management and control of activities prior to and during the hardware procurement phase are described to indicate the basis for obtaining visibility of the technical progress, utilization of resources, and cost performance of the contractors and other institutions supporting the Pioneer projects.

Spahr, J. R.↗

Reconciling the requirements of the science team and the spacecraft engineering team with a realizable optical system

Problems in the development of a suitable optical system for the imaging science payload of an interplanetary space probe are considered, taking into account the characteristics of the three categories of optical systems from which the engineer selects his system. These categories include the Catoptric or all mirror optical system, the Dioptric or all refracting optical system, and the Catadioptric system which combines elements of the other two categories. Examples of equipment selection and development in the preparation of a number of interplanetary space missions are discussed.

Larks, L.↗

The Pioneer Projects - Economical exploration of the solar system

The interplanetary Pioneer missions are reviewed in terms of management implications and cost control. The responsibilities, organizational structure, and management practices of the Pioneer Projects are presented. The lines of authority and areas of responsibility of the principal organizational elements supporting the Pioneer missions are identified, and the methods employed for maintaining effective and timely interactions among these elements are indicated. The technical and administrative functions of various organizational elements of the project are described. The management and control of activities prior to and during the hardware procurement phase are described to indicate the basis for obtaining visibility of the technical progress, utilization of resources, and cost performance of the contractors and other institutions supporting the Pioneer projects.

Spahr, J. R.↗

Trade study for water and waste management concepts. Task 7: Support special analysis

Cost analyses and tradeoff studies are given for waste management in the Space Station, Lunar Surface Bases, and interplanetary space missions. Crew drinking water requirements are discussed and various systems to recycle water are examined. The systems were evaluated for efficiency and weight savings. The systems considered effective for urine water recovery were vapor compression, flash evaporation, and air evaporation with electrolytic pretreatment. For wash water recovery, the system of multifiltration was selected. A wet oxidation system, which can process many kinds of wastes, is also considered.

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A demonstration of dual spacecraft tracking conducted with the Viking spacecraft during the approach phase

In the case of interplanetary space missions involving two spacecraft, such as Viking, significant navigation advantages may sometimes be achieved (at least for the trailing vehicle) by determining the orbit of one relative to the other, or otherwise combining the data from the two spacecraft. Dual spacecraft navigation concepts have been investigated by Chao et al. (1976). New analytical models for the dual spacecraft data types are presented and results are reported from a more recent demonstration conducted during the approach phase of the Viking mission. The demonstration was based on data taken two weeks before Mars orbit insertion of the second Viking spacecraft. The demonstration was designed to show that the approaching probe could be tied accurately to the planet through the orbiter. Attention is given to the geometry of the Viking B approach trajectory, the accuracy of the delivered estimates for midcourse maneuvers, and an algorithm of data processing.

Chao, C. C.↗

Interplanetary navigation in the 1980's and 1990's

Interplanetary space missions for the 1980's and 1990's will require more accurate and more automated navigation than the missions of the 1970's have required. Spacecraft which have orbited Mars and Venus, landed on Mars, and flown past Jupiter and Saturn are giving way to spacecraft which may orbit Jupiter, Saturn, Uranus, and Neptune, fly past Pluto, fly by or rendezvous with comets and asteroids, return samples from Mars, and fly close to the sun. Starting with the Voyager navigation system as a baseline, anticipated navigation requirements and performance for some of these candidate future missions are discussed, along with navigation system designs and strategies. Various developments in navigation technology, required or desirable for these missions, are treated.

Wood, L. J.↗

The Reed-Solomon encoders: Conventional versus Berlekamp's architecture

Concatenated coding was adopted for interplanetary space missions. Concatenated coding was employed with a convolutional inner code and a Reed-Solomon (RS) outer code for spacecraft telemetry. Conventional RS encoders are compared with those that incorporate two architectural features which approximately halve the number of multiplications of a set of fixed arguments by any RS codeword symbol. The fixed arguments and the RS symbols are taken from a nonbinary finite field. Each set of multiplications is bit-serially performed and completed during one (bit-serial) symbol shift. All firmware employed by conventional RS encoders is eliminated.

Perlman, M.↗

JPL Closeup

Voyager, Infrared Astronomical Satellite, Galileo, Viking, Solar Mesosphere Explorer, Wide-field/Planetary Camera, Venus Mapper, International Solar Polar Mission - Solar Interplanetary Satellite, Extreme Ultraviolet Explores, Starprobe, International Halley Watch, Marine Mark II, Samex, Shuttle Imaging Radar-A, Deep Space Network, Biomedical Technology, Ocean Studies and Robotics are summarized.

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Engineering challenges of in-flight spacecraft - Voyager: A case study

Some of the engineering problems encountered during the post-launch phase of interplanetary space missions are described, with emphasis given to the Voyager missions. The major in-flight modifications in Voyager spacecraft's operational capability with respect to communications, payload, and navigation systems are discussed. Attention is given to the instances of 'failure workaround' including: recovery from a failed receiver, recovery from a seized scan platform actuator, and modifications to the Attitude Articulation and Control Subsystem (AACS) software during the Saturn encounter. A detailed line drawing of the Voyager spacecraft is provided.

Jones, C. P.↗

The Deep Space Network

The Deep Space Network (DSN) is the largest and most sensitive scientific telecommunications and radio navigation network in the world. Its principal responsibilities are to support unmanned interplanetary spacecraft missions and to support radio and radar astronomy observations in the exploration of the solar system and the universe. The DSN facilities and capabilities as of January 1988 are described.

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Chemical launch system options for microspacecraft

The paper presents launch vehicle and upper-stage options for application to lunar and interplanetary microspacecraft missions. Particular attention is given to the capabilities of Piggyback, small launch vehicles, and large launch vehicles. It is noted that Piggyback options on the Shuttle and expendable launch vehicles enable near-term earth-orbital missions and the potential for lunar and planetary missions if an electric-propulsion upper-stage is developed. Launch systems like the Space Shuttle could be used to launch large members of microspacecraft in 'constellation deployment' and 'shotgun' class missions to a variety of solar-system targets such as the sun, asteroids, comets, the moon, Mars, and Saturn.

Sargent, Mark G.↗

Mechanical joints and large components for pathfinder in-space assembly and construction

This paper summarizes the background of the Pathfinder Project, In-Space Assembly, and Construction activity for fiscal year 1989. Work is presented on high strength mechanical truss joints and the definition of typical large components that might be required for assembly on-orbit and use on interplanetary space missions. Several mechanical joints were designed, and the most promising early design is presented in detail. The primary design drivers were the ability for robot assembly, the correction of up to a + or - 0.020 inch axial misalignment, and an axial load in the vicinity of + or - 100,000 lb. The most promising joint uses axisymmetric grooves to correct the misalignment and to transfer the load in a smooth path.

Finckenor, Jeff↗

IDE spatio-temporal impact fluxes and high time-resolution studies of multi-impact events and long-lived debris clouds

During the first 12 months of the Long Duration Exposure Facility (LDEF) mission, the Interplanetary Dust Experiment (IDE) recorded over 15,000 total impacts on six orthogonal faces with a time resolution on the order of 15 to 20 seconds. When combined with the orbital data and the stabilized configuration of the spacecraft, this permits a detailed analysis of the micro-particulate environment. The functional status of each of the 459 detectors was monitored every 2.4 hours, and post-flight analyses of these data has now permitted an evaluation of the effective active detection area as a function of time, panel by panel and separately for the two sensitivity levels. Thus, total impacts were transformed into areal fluxes, and are presented here for the first time. Also discussed are possible effects of these fluxes on previously announced results: apparent debris events, meteor stream detections, and beta meteoroids in observationally significant numbers.

Mulholland, J. Derral↗

SP-100 materials technology for SEI applications

General Electric and selected National laboratories are developing the SP-100 concept under the sponsorship of DOE,NASA and SDIO. Near term Space Exploration Initiative goals include the establishment of a lunar base, interplanetary manned missions, and the eventual establishment of a base on Mars. All of these projected missions have substantial power requirements. The SP-100 nuclear reactor has been identified as a promising power source to meet these requirements. This paper describes the material selections for SP-100, the factors driving the selection, and the progress to date in solving fabrication problems and producing the necessary properties data base.

Ring, P. J.↗

Track structure model for damage to mammalian cell cultures during solar proton events

Solar proton events (SPEs) occur infrequently and unpredictably, thus representing a potential hazard to interplanetary space missions. Biological damage from SPEs will be produced principally through secondary electron production in tissue, including important contributions due to delta rays from nuclear reaction products. We review methods for estimating the biological effectiveness of SPEs using a high energy proton model and the parametric cellular track model. Results of the model are presented for several of the historically largest flares using typical levels and body shielding.

Cucinotta, F. A.↗