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The Tracking and Data System and Deep Space Network preparation and support activities for the Pioneer Venus 1978 Mission are described including prelaunch preparations. The status of multiprobe entry preparations and the differential long base interferometry wind measurement experiment are summarized.
Ongoing Pioneer project operations (Pioneers 6 through 11) are briefly mentioned. The DSN prelaunch preparations and launch operations for the Pioneer Venus orbiter are described in detail, along with a brief update on the Pioneer Venus multiprobe launch and encounter preparations.
The Induced Environment Contamination Monitor (IECM), a set of ten instruments integrated into a self-contained unit and scheduled to fly on shuttle Orbital Flight Tests 1 through 6 and on Spacelabs 1 and 2, is described. The IECM is designed to measure the actual environment to determine whether the strict controls placed on the shuttle system have solved the contamination problem. Measurements are taken during prelaunch, ascent, on-orbit, descent, and postlanding. The on-orbit measurements are molecular return flux, background spectral intensity, molecular deposition, and optical surface effects. During the other mission phases dew point, humidity, aerosol content, and trace gas are measured as well as optical surface effects and molecular deposition. The IECM systems and thermal design are discussed. Preflight and ground operations are presented together with associated ground support equipment. Flight operations and data reduction plans are given.
A large scale field experiment, which was arranged in support of the Nimbus G - Coastal Zone Color Scanner (CZCS) project was studied. The experiment was to provide three air and two shipborne platforms simultaneously to members of the Nimbus G Experiment Team (NET) and to other scientists in order to collect data from common test sites. Besides establishing fundamental relations between the light in the sea and the biochemical properties of water, the data will be used mainly for the development of algorithms during the prelaunch phase of Nimbus G.
Ten samples of the Martian regolith have been analyzed by the Viking lander X ray fluorescence spectrometers. Because of high-stability electronics, inclusion of calibration targets, and special data encoding within the instruments the quality of the analyses performed on Mars is closely equivalent to that attainable with the same instruments operated in the laboratory. Determination of absolute elemental concentrations requires gain drift adjustments, subtraction of background components, and use of a mathematical response model with adjustable parameters set by prelaunch measurements on selected rock standards. Bulk fines at both Viking landing sites are quite similar in composition, implying that a chemically and mineralogically homogeneous regolith covers much of the surface of the planet. Important differences between samples include a higher sulfur content in what appear to be duricrust fragments than in fines and a lower iron content in fines taken from beneath large rocks than those taken from unprotected surface material. Further extensive reduction of these data will allow more precise and more accurate analytical numbers to be determined and thus a more comprehensive understanding of elemental trends between samples.
The Limb Infrared Monitor of the Stratosphere (LIMS) radiometer is a satellite-borne six-channel multispectral scanning radiometer using a two-stage methane and ammonia solid-cryogen cooler to cool the (Hg, Cd)Te focal plane to 65 K. The LIMS experiment employs thermal IR limb sounding to provide vertical-profile measurement of temperature and of concentrations of O3, NO3, and H2O in the stratosphere on a global scale. The goals of the experiment and the expected accuracies of the measurements are outlined, and the radiance measured by the radiometer is analyzed. A program of correlative measurements designed for verification and augmentation of the LIMS data is discussed. Detailed descriptions are given of the LIMS components and optics, the detector capsule assembly, the solid-cryogen cooler, the four operational modes of the LIMS system, and the data-processor electronics. It is noted that prelaunch acceptance testing thus far completed indicates that the LIMS specification design requirements have been met, and the experiment's performance goals can be achieved.
The paper presents the results of the prelaunch navigation studies conducted for the Mariner spacecraft launched toward encounters with the giant planets. The navigation system and the strategy for using this system are described. The requirements on the navigation system demanded by the goals of the project are mentioned, and the predicted navigational capability relative to each of the requirements is discussed. Baseline navigation results for three possible trajectories are analyzed.
The first satellite (HEAO-1) in the High Energy Astronomy Observatory Program series was launched successfully on Aug. 12, 1977. To date it has completed over nine months of orbital operation in a science data gathering mode. During this period all attitude control modes have been exercised and all primary mission objectives have been achieved. This paper highlights the characteristics of the attitude control subsystem design and compares the predicted performance with the actual flight operations experience. Environmental disturbance modeling, component hardware/software characteristics, and overall attitude control performance are reviewed and are found to compare very well with the prelaunch analytical predictions. Brief comments are also included regarding the operations aspects of the attitude control subsystem. The experience in this regard demonstrates the effectiveness of the design flexibility afforded by the presence of a general purpose digital processor in the subsystem flight hardware implementation.
A user guide for the MPP (Mission Planning Processor) is presented. The MPP is used in the evaluation of particular missions, with appropriate display and storage of related consumables data. Design goals are accomplished by the use of an on-line/demand mode computer terminal Cathode Ray Tube Display. The process is such that the user merely adds specific mission/flight functions to a skeleton flight and/or alters the skeleton. The skeleton flight includes operational aspects from prelaunch through ground support equipment connect after rollout as required to place the STS (Space Transportation System) in a parking orbit, maintain the spacecraft and crew for the stated on-orbit period and return.
The prelaunch mission operation report of the Fleet Satellite Communications System (FLTSATCOM-B) spacecraft is presented. The orbit requirements, mission profiles, parking orbit, and transfer orbit for the FLTSATCOM-B spacecraft are described.
The navigation and attitude reference performance of a strapdown system are investigated for applications to autonomous satellite launch and orbital operations. It is assumed that satellite payloads are integrated into existing missile systems and that the boost, orbit insertion, and in-orbit operation of the satellite are performed autonomously without relying on external support facilities. Autonomous and long term accurate navigation and attitude reference are provided by a strapdown inertial navigation system aided by a star sensor and earth landmark sensor. Sensor measurement geometry and navigation and attitude update mechanizations are discussed. Performance analysis data are presented for following functional elements: (1) prelaunch alignment; (2) boost navigation and attitude reference; (3) post boost stellar attitude and navigation updates; (4) orbital navigation update using sensor landmark measurements; and (5) in-orbit stellar attitude update and gyro calibration. The system performances are shown to satisfy the requirements of a large class of satellite payload applications.
Two cryogenic systems are described which will provide cooling for experiments to be flown on Spacelab 2 in the early 1980's. The first system cools a scanning infrared telescope by the transfer of cold helium gas from a separate superfluid helium storage dewar. The flexible design permits the helium storage dewar and transfer assembly to be designed independent of the infrared experiment. Where possible, modified commerical apparatus is used. The second cryogenic system utilizes a specially designed superfluid dewar in which a superfluid helium experiment chamber is immersed. Each dewar system employs a porous plug as a phase separator to hold the liquid helium within the dewar and provide cold gas to a vent line. To maintain the low vapor pressure of the superfluid, each system requires nearly continuous prelaunch vacuum pump service, and each will vent to space during the Spacelab 2 flight.
The NASA Small Self-Contained Payload or 'Getaway Special' program, allowing small experimental payloads to be flown on the Space Shuttle at low cost, is presented. The program allows any responsible person, organization or educational institution able to enter into a contract with NASA to fly a self-contained research and development payload compatible with spacecraft requirements and of weight less than 200 lb and volume less than 5 cu ft on the Space Shuttle, subject to space availability. Charges, based on package volume, range from $3000 to $10,000 in 1975 dollars, with a $500 deposit required as earnest money. NASA, in turn, will supply the shuttle flight and return, planning and technical information, the cylindrical container in which the payload is carried, control signals from the crew station, electrical power to the payload if available, elementary crew support, prelaunch testing or servicing and postflight information. Procedures for program participation are outlined.
ORT (Operational Readiness Test) software allows one engineer to test readiness of 64 minicomputers and their peripherals from single console. Software makes roll call of computers and peripherals via common data buffer to check readiness of system in morning "wake up" or at other important times. Subsystems are tested in parallel to save time. "Watchdog" terminates test of any system that does not respond in time, so one failed system does not halt test sequence. Entire rollcall is complete in about 15 minutes. Software is designed for Space Shuttle prelaunch checkout, but approach should interest users of similar equipment.
Accomplishments and future plans are described for the following areas: (1) geology - geobotanical indicators and geopotential data; (2) modeling magnetic fields; (3) modeling the structure, composition, and evolution of the Earth's crust; (4) global and regional motions of the Earth's crust and earthquake occurrence; (5) modeling geopotential from satellite tracking data; (6) modeling the Earth's gravity field; (7) global Earth dynamics; (8) sea surface topography, ocean dynamics; and geophysical interpretation; (9) land cover and land use; (10) physical and remote sensing attributes important in detecting, measuring, and monitoring agricultural crops; (11) prelaunch studies using LANDSAT D; (12) the multispectral linear array; (13) the aircraft linear array pushbroom radiometer; and (14) the spaceborne laser ranging system.
Studies related to the baseline navigation system for the orbiter are presented. The baseline navigation system studies include a covariance analysis of the Inertial Measurement Unit calibration and alignment procedures, postflight IMU error recovery for the approach and landing phases, on-orbit calibration of IMU instrument biases, and a covariance analysis of entry and prelaunch navigation system performance.
The paper discusses the development of a cryogenic helium system to provide cooling to a scanning infrared telescope for the Spacelab 2 mission. The infrared optical/detector system and related electronics are being developed by the Smithsonian Astrophysical Observatory and the University of Arizona. A superfluid helium dewar and porous plug phase separator permit gas cooling of the infrared focal plane assembly to about 2.5 K, and of the two telescope sections to 8 K and 60 K. The design of the cryogenic system,including a commandable vacuum cover, and the prelaunch liquid helium servicing and maintenance approach were discussed. It is concluded that the system will satisfy the Infrared Telescope requirements, and the superfluid helium system shall be capable of satisfying cryogenic helium cooled requirements for the next several years.
Spectral analysis of water color and concurrent measurements of the relative concentration of various particulate and dissolved constituents within a broad range of water types are necessary to quantify ocean color observations and successfully relate them to various biological and physical processes that can be monitored by remote sensing. Some of the results of a Nimbus-G prelaunch cruise in connection with the Coastal Zone Color Scanner (CZCS) experiment, which was carried out in the Gulf of Mexico in October 1977, are presented and discussed. Based upon a small but diverse sample of near-surface measurements, it appears possible to estimate total suspended particulate matter (SPM) to useful accuracies by forming ratios of the spectral radiances measured at wavelengths falling near the centers of certain CZCS bands, viz., 440 nm:550 nm and 440 nm:520 nm. Furthermore, the analysis suggests a very high degree of covariation between SPM and phytoplankton pigments except for certain well-defined special cases.