Jun 12 1978
From The Space Library
Av Wk reported that engineers suspected a hot-gas system leak in the sustainer engine of the USAF/General Dynamics Atlas F launch vehicle as the cause of over temperatures registered during recent DOD NavStar launches from Vandenberg AFB. Over temperatures in the boattail area of the Atlas F (recorded in telemetry from the launches of NavStar 1 in Feb. and NavStar 2 in May) had forced postponement for at least 14days of SEASAT-A's launch from Vandenberg. Rockwell International's Rocketdyne Div. had test-fired the engine to determine whether a leak in the sustainer engine's hot gas system was responsible, and to pinpoint the location of the leak. They also had hot-fired sustainer-engine gas generators as part of the investigation. General Dynamics had monitored aerodynamic flow around the Atlas F during flight for hot gas from the exhaust plume impinging on the boattail.
Temperatures in the boattail had climbed earlier than expected during the NavStar launches; in one launch, that area had become hot enough to melt insulation on copper wires, causing failure of some onboard instruments and intermittent operation of others. NASA had increased insulation on some wire bundles in SEASAT-A's Atlas F; more insulation around other rocket's components might also be added. Additional instruments installed in the launch vehicle should obtain more details on temperature and pressure conditions in the boattail area during launch, program officials noted. They had not decided whether to postpone launch of the third NavStar satellite, planned for Aug. (Av Wk, June 12/78, 18)
Av Wk reported MSFC's intent to demonstrate within 5yr the assembly of a large space structure in low-earth orbit, to exploit Space Shuttle capability. MSFC had proposed assembling a 10 x 30m (33 x 98ft) structure in space to demonstrate fabrication and assembly techniques, followed closely by a Space Shuttle mission to demonstrate deployment of a large antenna 50 to 200m (164 to 656ft) in diameter. The USAF Space and Missile System Organization (SAMSO) had also expressed interest in flying a Shuttle-based antenna-deployment test before 1985.
Although most U.S. aerospace companies had been working on structures in space, Grumman Aerospace Corp. had been in the forefront in large space-structures work; MSFC had awarded Grumman four of six contracts for large space structures development, and JSC had awarded it at least one significant contract. MSFC's approach had been to define tools and procedures needed, and to evaluate whether such operations would be possible and to what degree. Most building-block study for large space structures had assumed the use of open-truss aluminum beams joined by diagonal and cross braces, with beam sections lm (3.2ft) wide and length varying according to mission. Grumman had just begun to demonstrate a beam-building machine [see Apr. 12]. Both NASA and Grumman had been scheduled to evaluate the beams for deviations from specifications such as straightness or basic strength, and for individual subsystems such as the automatic welders used to affix the cross sections. In Sept. Grumman would transfer the beam-builder to MSFC for tests of beam manufacturing in a vacuum, to simulate space conditions. (Av Wk, June 12/78, 49)
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