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Aviation History
1990
1990 - 1932.PDF
OPERATIONS: SPACEFLIGHT Hydrogen leaks suspend Shuttle suspen e BY TIM FURNISS Space Shuttle missions have been suspended while NASA investigates the cause of gaseous hydrogen leaks during external- tank propellant loading in preparation for the STS 35 Columbia and STS 38 Atlantis missions. A leak six hours before the launch of STS 35 on 3f May cancelled the mission and Columbia was rolled back from its pad on 12 June. During a propellant-loading test on 29 June in preparation for the STS 38 Atlantis Department of De fense mission in mid-July, a simi lar but smaller leak was detected. This mission too has been cancelled. The leaks were detected in a cavity between the orbiter and external-tank umbilical plates of the 42.5cm disconnect line, which is used to transfer propel lant from the tank to the three Shuttle main engines. The leak is very small, measured in "parts per million", says Dr William Lenoir, NASA's associate admin istrator for spaceflight. The STS 38 leak is "both temperature and flow rate dependent," says NASA. Lenoir says that Atlantis will be removed from the pad and no missions will proceed until the cause of the leaks has been found and a solution established. A major remanifest of Shuttle flights will result from the delay. It now seems highly likely that the next Space Shuttle mission will be STS 41 Discovery on 5 October, to carry the Ulysses solar polar orbiter—although Lenoir believes that one of the cancelled missions could be flown before October. Missing the 19-day October launch window, the tightest so far for a Shuttle mission, would mean delaying Ulysses for 18 months. Lenoir says that even if Discov ery is rolled to the pad and a propellant flow test indicates no leaks, if the cause of the STS 35 and 38 problems is not fully understood, then STS 41 would also not fly. Atlantis will remain on the pad for further tests before its roll Hydrogen leaks detected on 29 June de back. A helium pressure check of the external tank conducted on 3 July revealed no leaks, further mystifying engineers The dis connect line of Columbia has been removed and replaced by the component on the new or biter, Endeavour, being built at Rockwell. NASA has flown ten successful ted the mid-July Atlantis mission Shuttle missions since the Chal lenge* crash and Lenoir hupes that the two hydrogen leaks are no mote than coincidence A full investigation has been ordered to review hardware design, processing, data analysis and fault tree analysis, with an independent support group of "NASA old hands" to assist • Ariane launches set to restart Ariauespace commercial sat- xVellite launches are set to re start following the failure of an Ariane launcher on 22 February. Ariane V37 will be launched no earlier than 24 July, carrying the TDF 2 and DFS 2 communica tions satellites. The failure of V36 was caused by fuel- and water-line mal functions in an L33 liquid strap- on booster and a Viking L220 engine of the 44L booster's first- core stage. The same model will be used to launch TDF and DFS. Arianespace may be able to conduct four further launches this year in an attempt to catch up on the backlog of the 15 1990-scheduled satellites in the wakeofV36. D Gravity-assisted Giotto flies by The European Space Agency's Giotto spacecraft performed the first Earth fly-by gravity- assist manoeuvre on 2 July, skimming past the planet at a distance of 217,600km, en route for a new cometary fly-by of Grigg-Skjellerup in 1992. The rejuvenated spacecraft flew through Halley's Comet in 1986. Giotto will be followed in an Earth gravity-assist manoeuvre by NASA's Galileo, which was launched towards the planet Ju piter from the Space Shuttle last October. It flew past Venus in February and on 8 December will fly within 1,000km of Earth. A closer encounter of just 300km is due in December 1992. • NEWS IN BRIEF CARINA GOES AHEAD The Italian Space Agency is to proceed with the development of the Carina unmanned recoverable experiment-carry ing spacecraft, with Aeritalia leading the programme. The spacecraft will be offered commercially mainly to the materials processing community. June satellite launch log No 49 50 51 52 53 54 55 56 57 Date Jun 1 Jun8 Jun 12 Jun 13 Jun 19 Jun 20 Jun 21 Jun 23 Jun 27 Spacecraft Rosat DoD Insist 1D Molniya 3 Cosmos 2083 Gorizont 20 Cosmos 2084" Intelsat 6 Meteor 2 Type Astronomy Elint Comms/Obs Comms Recon Comms Early warn Comms Metsat Launcher Delta Titan 4 Delta Molniya Soyuz Proton Molrnya Cornm Titan Tsyklon Launch site Canaveral Canaveral Canaveral Piesetsk F.e:-eisk Baikonur ' Ple,etik Canaveral Piescisk 'Stranded in useless orbit after upper stage failure Contact lost 14 FLIGHT INTERNATIONAL 11-17 July 1990
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