henry@utzoo.uucp (Henry Spencer) (06/04/90)
Payload Systems, which recently flew a commercial payload on Mir, says that Soviet paperwork was just as much of a nuisance as NASA paperwork, but in general things went more quickly in Moscow and Baikonur than in Washington and the Cape. Why? Because most disagreements could be eliminated quickly and quietly by simply paying more. HST is up and functioning, after headaches during solar-array deployment. When the array masts were ordered to swing out to proper position, they did so, but telemetry indicated they had not locked. McCandless and Sullivan were told to prepare for an EVA as a precaution, while Goddard controllers commanded the mast motors to full power in a second attempt. This succeeded, but raised doubts about control electronics, and in particular made controllers wonder whether the deployment-complete sensors on the arrays themselves would work. The astronauts were told to order a manual halt when the arrays reached full extension, in case the automatic halt failed. The port-side array deployed flawlessly. However, sending of the manual-halt command also cut off telemetry on deployment and locking, and there was some delay while things were restarted momentarily to check. Then came the starboard array, which moved out a few inches... and stopped. After half an hour of trouble- shooting, it was tried again, and again stopped after about 30 seconds. McCandless and Sullivan, by this time suited up and ready, were told to start depressurizing the airlock. Meanwhile, Goddard tried to sort out what was going on. The camera views showed everything normal (this array was not visible from the orbiter windows). The major reason for halting deployment early would be excessive tension on the array -- i.e. something sticking -- but tension showed as normal in the telemetry. A third attempt was made with the array controller's tension limits disabled, and it worked. The final orbit for HST was 332x331nmi, a record for the shuttle and the highest US astronauts have flown since Apollo 17. Originally 330 was the target, but it turned out that an extra 1-2nmi was available, and of course they took it. HST launched three minutes late due to human error. A fix to avoid a potential safety problem (possible trouble if ground computers lost power at a crucial moment) had been put in manually, and as a result a crucial valve was open instead of closed at T-48s. The software noticed it and stopped the count. The controllers said "oops", tidied things up, and picked up the count with the valve properly closed. Orbital Sciences goes public, selling 2.4M shares of common stock at $14 each in the wake of the successful Pegasus launch. An earlier plan to offer stock at $13 had been halted due to skeptical press reports before the launch. Pictures of LDEF stripped down to the frame, and various experiments and pieces thereof. There is starting to be discussion of reflying LDEF, possibly as a paying joint venture with a commercial firm. Most of LDEF's experimenters would like another chance to fly, as would many who lost out in the competition for the first-flight payloads. There is no firm decision yet, except that the structure will not be broken up or donated to a museum for at least a year. There would be some difficulty in getting a new launch slot soon, as LDEF is big and heavy. Pictures of microcraters in LDEF experiments. First-look results from the experiments are starting to come in. Although there is a lot of visible weathering on external surfaces, that *is* strictly a surface phenomenon; the insides are fine. Lewis Research Center's solar-cell experiment was actually alive and recording data until early last year, in a low-power hibernation mode that minimized battery drain. Most of the hardware from the experiments still works. Some of the tape recorders are stuck over the capstans, but that happens even on Earth when recorders are idle for long periods. Pretty well everyone has good data, although some experiments did not function perfectly. LDEF's chief scientist, William Kinard, says the results so far indicate that there is no problem for long-life space systems if some care is taken about the outer surfaces. Atomic-oxygen erosion attacks materials on the leading face, so those materials must be chosen carefully. However, it looks like even composites are usable with proper protective coatings. A slight surprise is that most meteorite/debris impacts are on the leading face, with very strongly directional behavior. However, the "meteor bumper" approach -- using an outer layer to vaporize incoming objects so nothing solid reaches an inner layer -- works very efficiently, even better than was expected. "We've got situations where thermal blankets have 400-500 penetrations in them, and we have to look extremely hard for any marks on the surfaces underneath..." LTV and SNIA BPD [a Fiat subsidiary] agree on the development of the San Marcos family of small launchers, souped-up versions of Scout. The first version is expected to be a Scout with a new fourth stage and two big strap-on boosters. More and bigger strap-ons are the obvious route to further growth. Combined Release and Radiation Effects Satellite arrives at KSC for Atlas-Centaur launch in mide-June. The satellite will map the Van Allen belts in detail and release chemicals into space to study interactions with the atmosphere and magnetosphere. [From Flight International, 21 March:] Aeritalia completes assembly and tests of the Tethered Satellite project, for shuttle launch in May 1991. The Christics and their buddies are getting organized to try to stop the Ulysses launch in October, since Ulysses is (gasp) nuclear powered, carrying a single isotope generator similar to the ones on Galileo. [From Flight International, 28 March:] Spacehab, the private-venture middeck-extension module for the shuttle, gets its necessary funding, from a consortium of banks led by Central Bank and including The Mitsubishi Bank, Banque Nationale de Paris, and Banque Paribas. Hardware construction has begun in Turin (Aeritalia is a major subcontractor). Giotto successfully retargeted for Earth encounter this summer, taking it on to comet Grigg-Skjellerup in 1992. India announces plans to keep on trying to build its own launchers, despite two failures of its ASLV in a row (in 1987 and 1988). The next ASLV launch attempt will be next year. [From Flight International, 25 April:] Alexander Alexandrov, Soviet cosmonaut and manager of cosmonaut training, says flights by mixed-gender crews cause "moral and ethical problems" and there will be no more female cosmonauts for now. [And a late note to LDEF fans: the coverage of the LDEF retrieval in the March 1990 issue of Spaceflight (one of the BIS's journals) struck me as the best of the bunch, better than either Aviation Week or Flight International and beating out the other space magazines by a mile. Spaceflight still gets my nomination for best all-round space periodical.] -- As a user I'll take speed over| Henry Spencer at U of Toronto Zoology features any day. -A.Tanenbaum| uunet!attcan!utzoo!henry henry@zoo.toronto.edu