henry@utzoo.uucp (Henry Spencer) (05/08/89)
[This is the "Aerospace Forecast & Inventory" issue, heavy on overviews and tables and light on current news.] An amazing picture of the "waveguide labyrinth" (its official name) for an Intelsat 6. Or rather, one of the eight for each Intelsat 6. Looks like a map of an ant colony, done in aluminum and the size of a tabletop. They provide beam shaping for the main transmit and receive beams, including pattern switching depending on whether the satellite is over the Atlantic, Pacific, or Indian Ocean. Intelsat would like to replace them with active-element phased-array systems, once costs come down a bit further; this would permit post-launch pattern changes and simplify satellite design. SDI proposes start of production of a "conventional" strategic defense system in 1994-5, but Abrahamson [recently retired as SDI director] says that the "Brilliant Pebbles" concept is probably superior. Postmortem on the March 13 Discovery launch and mission. They got off in time to clear the pad for Magellan, despite some tense moments. [As most everybody has probably heard, Magellan is on its way now. Okay, so I'm a bit behind...] NASA used some revised weather-management methods, notably having alternative trajectory profiles ready in case of unusual wind patterns aloft. It paid off; one of the alternate profiles was in fact used, after it became clear that high-altitude winds differed from the historical average that's used to plan the main profile. The third operational TDRS was deployed successfully, completing the operational system for the moment and permitting closure of six more tracking stations (net saving, $35M/yr). Tests of the "Share" advanced heat-pipe radiator design being considered for the space station did not go well. Basically, it didn't work, and it overheated when experimental heaters were switched on. Current guess is that bubbles in the fluid system were to blame, although an attempt to dislodge them with orbiter thruster firings wasn't successful. The station engineers report that they have learned quite a bit and may want to fly the experiment again. DoD says the new Asat project will yield a system that could be fielded in the mid-90s, assuming it survives the inevitable political battles. The initial design is likely to be a surface-launched rocket carrying an optical homing head; both sea and land-based options are available. The Pentagon wants to spend almost $200M in FY90 on it; Congress isn't expected to be too happy about it. One problem is that there is no agreement about how capable the Soviet Asat system (which is believed to have been operational for about a decade, but has not been tested recently) is. -- Mars in 1980s: USSR, 2 tries, | Henry Spencer at U of Toronto Zoology 2 failures; USA, 0 tries. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu