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The science objectives of Pioneer Venus and future investigations of the planet are discussed. Concepts and payloads for proposed missions and the supporting research and technology required to obtain the desired measurements from space and Earth-based observations are examined, as well as mission priorities and schedules.
Biological goals were among the important science objectives of the Viking lander camera. The camera performance characteristics relevant to these goals are discussed. They include the ability to observe (1) morphological detail, (2) color and reflectance spectra, and (3) motion and change. The scenes obtained by the cameras were scrutinized in many ways: monoscopically, stereoscopically, in color, and by computerized differencing of camera events. At the lander sites and during the times that observations were carried out on the surface of Mars, no evidence, direct or indirect, has been obtained for macroscopic biology on Mars. No obvious examples of geometric distortion that might have been motion induced have been observed. Using the repeated line scanning mode of the camera has revealed no changes or motion suggesting life. These negative results may be due to limitations in sampling, in camera design, or in our understanding of Martian biology, but they are certainly consistent with the hypothesis that macroscopic life is absent on Mars.
A spaceborne lidar system for atmospheric studies was defined. The primary input was the Science Objectives Experiment Description and Evolutionary Flow Document. The first task of the study was to perform an experiment evolutionary analysis of the SEED. The second task was the system definition effort of the instrument system. The third task was the generation of a program plan for the hardware phase. The fourth task was the supporting studies which included a Shuttle deficiency analysis, a preliminary safety hazard analysis, the identification of long lead items, and development studies required. As a result of the study an evolutionary Lidar Multi-User Instrument System (MUIS) was defined. The MUIS occupies a full Spacelab pallet and has a weight of 1300 kg. The Lidar MUIS laser provides a 2 joule frequency doubled Nd:YAG laser that can also pump a tuneable dye laser wide frequency range and bandwidth. The MUIS includes a 1.25 meter diameter aperture Cassegrain receiver, with a moveable secondary mirror to provide precise alignment with the laser. The receiver can transmit the return signal to three single and multiple photomultiple tube detectors by use of a rotating fold mirror. It is concluded that the Lidar MUIS proceed to program implementation.
An analysis of the potential capabilities of a spectrally diversified DIAL technique for monitoring atmospheric species is presented assuming operation from an earth-orbiting platform. Emphasis is given to the measurement accuracies and spatial and temporal resolutions required to meet present atmospheric science objectives. The discussion points out advantages of spectral diversity to perform comprehensive studies of the atmosphere; in general it is shown that IR systems have an advantage in lower atmospheric measurements, while UV systems are superior for middle and upper atmospheric measurements.
During January 1982 the NASA space transportation system will launch a Galileo spacecraft composed of an orbiting bus and an atmospheric entry probe to arrive at the planet Jupiter in July 1985. A prime element of the orbiter's scientific instrument payload will be a new generation slow-scan planetary imaging system based on a newly developed 800 x 800 charge-coupled device (CCD) image sensor. Following Jupiter orbit insertion, the single, narrow-angle, CCD camera, designated the Solid State Imaging (SSI) Subsystem, will operate for 20 months as the orbiter makes repeated encounters with Jupiter and its Galilean Satellites. During this period the SSI will acquire 40,000 images of Jupiter's atmosphere and the surfaces of the Galilean Satellites. This paper describes the SSI, its operational modes, and science objectives.
Topics included in the WISP science objectives are: (1) VLF wave injection experiments; (2) traveling ionospheric disturbances and atmospheric gravity waves; (3) ionospheric bubbles; and (4) plasma wave physics. Flow charts of the WISP investigation organization, the project life cycle and the instrumentation are given.
The Large Aperture Telescope (LAT), which will have a diameter of 10-30 m and will operate in the 2-1000 micron wavelength range, is described. It is noted that the LAT could be carried into orbit with a single launch of the Space Transportation System and semiautomatically deployed as a free flyer with a nominal 10-yr mission duration. Servicing and instrument changes would be made at 2-yr intervals. It is pointed out that the LAT would have to be placed above the earth's atmosphere to avoid both the absorption that occurs through much of the infrared and submillimeter and the turbulence which limits spatial resolution. Important technical considerations for the LAT are discussed; they include the telescope optical form, the primary mirror material, figure control techniques, the deployment techniques, and thermal control. The science objectives and rationale for the LAT are discussed and various hardware techniques and concepts for its implementation are described.
The Galileo mission to Jupiter in the latter half of this decade is NASA's next step in the exploration of Jupiter. The primary science objectives are to study the satellites, the magnetosphere, and Jupiter's atmosphere. In general, there are four characteristics of the Galileo mission which provide the capability to address questions not answered by Voyager: (1) long-term observations - at least 11 orbits of Jupiter in nearly two years - will allow temporal studies of Io vulcanism as well as of interactions between the satellites and magnetosphere; (2) very close satellite flybys - at a distance less than 1000 km at each Galilean satellite - will allow in-depth studies of these satellites at distances 20 to 100 times closer than Voyager achieved; (3) an atmospheric entry probe will measure composition, structure, temperature, energy balance, cloud layer locations and structure, and particle size distribution in Jupiter's atmosphere; and (4) the Orbiter's advanced instrumentation will allow higher resolution and more detailed studies of the satellites, atmosphere, and magnetosphere
The Dynamics Explorer program of NASA is designed to study the coupling of energy, electric currents, electric fields, and plasmas between the atmosphere, ionosphere, and the magnetosphere. The program is composed of two well instrumented polar orbiting satellites and ground operations and data handling systems which have been designed to acquire, process, and make readily available to the scientists of the program the data sets necessary for analysis to accomplish the science objectives. These systems are described with emphasis placed on the relationship of the two instrumented spacecraft and the ground systems to their roles in meeting the program requirements. In addition, the characteristics of the orbits selected are specified.
The Dynamics Explorer A High-Altitude Plasma Instrument (HAPI) will make differential measurements of the velocity-space distributions of electrons and positive ions over the energy/charge range of 5 eV to 32 keV. Five identical analyzers, each making simultaneous measurements of electrons and positive ions at 64 possible energy levels, will have viewing angles of 45, 78, 90, 102, and 135 deg relative to the spacecraft spin axis. The HAPI data will contribute to the overall Dynamics Explorer science objectives, particularly by providing information on the hot-plasma effects of the coupling of energy, mass, and momentum within the earth's atmosphere, ionosphere, and magnetosphere.
Post-Galileo mission concepts considered possible for satellite-intensive investigations are presented, with consideration given to single and multiple target scenarios using orbiter and lander deployments. Candidate missions that satisfy the selected science objectives are identified, and specific scenario/target combinations which fall within performance constraints are chosen. The concepts are then developed into descriptive mission profiles. Also discussed are target encounter and deployment requirements, payload delivery, and operational considerations. Particular attention is given to Jupiter radiation effects and shielding requirements. A wide range of satellite-intensive missions is thought to be within the performance capabilities of earth-gravity-assisted ballistic trajectories and nuclear electric propulsion technology.
A description of the Solar Maximum Observatory and the operational status of its instrument systems is presented. The major science objectives which could be made possible with repairs to the spacecraft are defined. Hardware requirements and procedures for a repair mission are detailed. In general the mission involves: (1) the capture and control of the observatory in free flight by an astronaut in the manned manipulator unit; (2) berthing the observatory to the orbiter with the remote manipulator system; and (3) repairing the scientific instruments and replacing the attitude control system through extravehicular activity.
The report develops a ten-year science strategy for investigating the solid earth and dynamics of world oceans from Earth orbit. The strategy begins from the premise that earth studies have proceeded to the point where further advances in understanding Earth processes must be based on a global perspective and that the U.S. is technically ready to begin a global study approach from Earth orbit. The major areas of study and their fundamental problems are identified. The strategy defines the primary science objectives to be addressed and the essential measurements and precision to achieve them.
The Mars Orbiter Water Mission (MOWM) is discussed as an example of a low-cost, low-risk focused-science Mars mission which might be implemented in the near term within recently imposed fiscal constraints. MOWM is designed to act as a follow-on to the Viking results in the areas of comparative climatology and water, carbon dioxide and dust inventories. The STS-compatible space vehicle would be based on proven earth-orbiting satellite hardware, fulfilling requirements for both spinning and despun components, operation with nonoptimum solar cell orientation, PAM-A upper stage compatibility, and data storage for delayed transmission. Study results have shown the technical and economic feasibility of missions based on any of four submitted designs which meet these requirements, and of low-cost, well-focused science objective Mars missions in general.
The CCD detector under construction for use in the slow-scan television camera for the NASA Galileo Jupiter orbiter to be launched in 1985 is presented. The science objectives and the design constraints imposed by the earth telemetry link, platform residual motion, and the Jovian radiation environment are discussed. Camera optics are inherited from Voyager; filter wavelengths are chosen to enable discrimination of Galilean-satellite surface chemical composition. The CCO design, an 800 by 800-element 'virtual-phase' solid-state silicon image-sensor array with supporting electronics, is described with detailed discussion of the thermally generated dark current, quantum efficiency, signal-to-noise ratio, and resolution. Tests of the effect of ionizing radiation were performed and are analyzed statistically. An imaging mode using a 2-1/3-sec frame time and on-chip summation of the signal in 2 x 2 blocks of adjacent pixels is designed to limit the effects of the most extreme Jovian radiation. Smearing due to spacecraft/target relative velocity and platform instability will be corrected for via an algorithm maximizing spacial resolution at a given signal-to-noise level. The camera is expected to produce 40,000 images of Jupiter and its satellites during the 20-month mission.
The design process and performance of the NASA High Energy Astronomy Observatories (HEAO-1, 2, and 3) are surveyed from the initiation of the program in 1968 through the end of HEAO-3 operation in May, 1981, with a focus on the attitude control and determination subsystem (ACDS). The science objectives, original and revised overall design concepts, final design for each spacecraft, and details of the ACDS designs are discussed, and the stages of the ACDS design process, including redefinition to achieve 50 percent cost reduction, detailed design of common and mission-unique hardware and software, unit qualification, subsystem integration, and observatory-level testing, are described. Overall and ACDS performance is evaluated for each mission and found to meet or exceed design requirements despite some difficulties arising from errors in startracker-ACDS-interface coordination and from gyroscope failures. These difficulties were resolved by using the flexibility of the software design. The implicationns of the HEAO experience for the design process of future spacecraft are suggested.
Starlab science objectives, ground system considerations, space shuttle sortie, space platform/station, mission planning, and remote facilities are addressed.
A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.