henry@zoo.toronto.edu (Henry Spencer) (08/20/90)
Editorial commenting that the history of HST's mirror problems can be traced pretty easily to what Perkin-Elmer managers told Congress in 1983: "Our problems resulted from a combination of underestimating technical challenges and the cumulative effect of funding shortages. This funding shortfall in turn resulted in elimination of development testing, cutbacks on critical support hardware, interruption in certain developmental efforts and general operational inefficiencies." Space-station preliminary design reviews underway, involving about 500 people. [!] Design is considered about 20% complete. [Well, it's only been eight years, after all... :-[ ] US government and industry to supply Japan with spare parts after fire damage to a first-stage engine endangers the launch date for Japan's ERS-1 earth-resources satellite. [The Japanese H-1 launcher is partly a Delta derivative.] Excrement hits fan for Hubble Telescope as mirror flaw is discovered. The Wide Field / Planetary Camera is considered useless. [It now appears that this may have been slightly pessimistic.] The Faint Object Camera will be no better than ground instruments, except in the ultraviolet, barring the possibility of computerized image enhancement. The High- Resolution Spectrograph is primarily an ultraviolet instrument, and its users are overjoyed at getting more observing time; the only impact on it is difficulty in working in very crowded fields of view where many stars are very close to each other. The Faint Object Spectrograph is likewise largely unaffected except for crowded-field work, although there had been plans for coordinated FOS-FOC work that may be hampered by the FOC's problems. The High Speed Photometer will be able to do about 50% of its planned work, the parts losing out being those that need a high signal-to-noise ratio. The Fine Guidance Sensor Astrometry work, including search for planets around nearby stars, should be nearly unaffected. Columbia's hydrogen leak forces replacement of major plumbing components with ones borrowed from Endeavour. Commercial Titan successfully launches another Intelsat VI, with various precautions in place to avoid a repetition of the stranding of the last one. Pad 40 now goes offline for two years for renovations, with activity to resume with the launch of Mars Observer in Sept 1992 (the only other firm customer for CT at this time). Martin Marietta has decided to focus CT marketing on US government customers in future. House kills Moon/Mars funding, despite a general budget increase for NASA overall. Various constraints have been imposed on the station, including availability of the full 75kW of power before any non-US modules go up, and placement of life-science centrifuge equipment and animal holding cages elsewhere than the US microgravity lab. Motorola proposes a $2.3G light-satellite network to establish essentially a global cellular-telephone system. The "Iridium" system would use 77 315kg satellites in low polar orbits. The bulk of them would go up in clusters on medium boosters, with individual replacement birds launched as needed by small boosters like Pegasus. The eventual hope is to launch a replacement satellite within 36 hours of a failure. The satellites use phased-array antennas to project multiple coverage cells onto the Earth, and relay calls among themselves to make long-haul connections. The intent is to have mobile phones that automatically select a ground-based cellular network when available (since it will probably be cheaper) and resort to Iridium in remote areas and during disasters. The low orbit calls for many satellites, but minimizes transmitter power and eliminates the delays and echos of Clarke-orbit phone connections. Motorola would prefer to just build the satellites and ground equipment, but will join a financing consortium if necessary; negotiations with Inmarsat, American Mobile Satellite Corp, and Telesat Mobile Inc (of Canada) are underway. The political and regulatory obstacles will be the big ones. Relay Mirror Experiment satellite successfully bounces a laser beam from the Maui Optical Observatory to a target at Kihei. -- Committees do harm merely by existing. | Henry Spencer at U of Toronto Zoology -Freeman Dyson | henry@zoo.toronto.edu utzoo!henry