Jun 19 1978
From The Space Library
As the climax of a 4-mo attempt to stabilize and trim the orbital position of Skylab, a NASA team of engineers and controllers from JSC, MSFC, IBM, and three tracking stations (Bermuda; Madrid; and Goldstone, Calif.) had successfully put the space station in an orbital position they hoped would prolong its lifetime in space, JSC announced. Maneuvers in June had put the space station in an attitude intended to reduce atmospheric drag at its orbital height of 389km (242 statute mi). Assuming that the gyros continued to function, NASA hoped the- new attitude would extend the orbital lifetime of Skylab by 6 to 12mo to late 1979 or early 1980, giving NASA time to arrange an early Space Shuttle test flight to reboost Skylab into higher orbit, or deorbit it into a remote ocean area.
Maneuvers had begun in Mar. when engineers and flight controllers at the Bermuda tracking station checked out Skylab systems and brought its batteries to a fully charged state. On June 8, flight controllers had turned on the dormant control-moment gyros in the Skylab attitude-control system. (The other part of the system, the thruster attitude-control system, would expel nitrogen gas through nozzles to move Skylab into various attitudes in its orbit.) A computer with various sensors to indicate position had controlled both systems. Although one gyro that failed during the last Skylab mission in 1974 could not be used, the other two gyros were activated and worked as expected.
On June 9, controllers had commanded Skylab into a solar inertial attitude in which the spacecraft's solar cells always faced the sun. On June 11, they had maneuvered it into the desired "end-on velocity-vector" attitude, docking port forward and long axis parallel to the ground along the flight path. Skylab had remained in that position while engineers continued to monitor it, periodically transmitting minor corrections to the onboard computer controlling Skylab's position. (JSC Release 78-25; Marshall Star, June 7/78, 1; June 14/78, 1; JSC Roundup, June 9/78, 1; June 23/78, 1; DFRC X-Press, June 2/78, 2; June 30/78, 2; W Post, June 12/78, A-19))
MSFC had designed a geostationary-orbit platform that could perform the functions of more than a dozen domestic communications and weather satellites serving North America, Av Wk reported. As early as 1986, NASA could use the Space Shuttle to assemble the platform, first U.S. large space structure in synchronous orbit. NASA would assemble the platform over the course of three Space Shuttle missions, using technology under design at MSFC and JSC. Analysis had predicted that over a platform's 15-yr lifetime it could save 50% of the cost of operating communications and weather systems now scheduled to be placed in synchronous orbit during that period.
Institutional rather than technical barriers had delayed completion of the platform project, but MSFC had reached agreement among common carriers and hardware manufacturers on the savings possible by using the platform. One concern of NASA planners was that grouping communications systems on a single platform would make them more vulnerable to Soviet attack; however, MSFC planned to issue an RFP of about $500 000 for major systems studies in FY79 and FY80 that would constitute Phase A evaluation of typical platform requirements; phase B would require about $1 million for FY80 and FY81 for system design concepts. (Av Wk, June 19/78, 67)
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