Letter from Joe Ratcovic at Litton, observing that AW&ST was a bit behind the times when it said "the next advance to be applied to space [gyros] could be interferometric fiber-optic gyroscopes [IFOGs]": Clementine's primary attitude-reference system used Litton IFOGs.
Magellan goes down into Venus. Periapsis-lowering firings were done as planned in the morning of 11 Oct, briefly interrupted when Magellan dropped into safe mode after the first firing because the engineers had forgotten to disable some fault protection. Good aerobraking data was obtained, the required thruster firings were smaller than expected, and the electronics behaved themselves to surprisingly low battery voltages. At 0305 PDT on 12 Oct, Magellan went behind Venus on orbit 15032, and somewhere between then and the next scheduled contact, either it lost attitude control due to fuel exhaustion, or the electronics started misbehaving as the batteries declined. Intermittent signals were seen until about 1100 [this actually isn't mentioned in AW&ST, but it comes from other reliable sources], but full contact was never regained. Actual burnup probably occurred around noon the next day.
Israel announces intent to open commercial marketing of its Shavit launcher, and to develop a larger version with stretched first and second stages and a new liquid-fuel fourth stage. The new version, dubbed "Next", will be capable of 300kg launches into polar orbit. US marketing, including entry in NASA's ultralight-launcher competitions, is planned. Israel's own third satellite, the third Offeq, is slated for launch early next year; it will carry imaging sensors.
China announces plans to develop its own navsat system, Twin-Star, using a pair of Clarke-orbit satellites and providing some "timing and communications" capabilities not available through GPS or Glonass. [Sounds like they're planning a revival of the late lamented Geostar.]
Also in China's plans is a constellation of ten 250kg remote-sensing satellites, with seven carrying 100m visible imagers and three carrying infrared imagers. The system will emphasize frequent coverage rather than high resolution, with twice-a-day coverage of most areas of Earth giving much better monitoring of fast-moving events like floods than that provided by Landsat and Spot.
France announces a new experimental comsat, Stentor (for 1999 launch), and the next extension of the Spot line, Spots 5A and 5B (for launch in 1999 and 2003, carrying 5m imagers).
ESA awards contract for its X-ray Multi Mirror spacecraft to DASA. Launch planned for 1999.
When the imminent Atlantis flight deploys and retrieves the Crista-Spas atmospheric-research free-flyer, it will make the retrieval approach using a new technique planned for the Shuttle-Mir flights. The new "plus R bar" approach, approaching the target from below, is attractive for rendezvous with large and fragile structures (like Mir) because it involves few or no jet firings toward the target: orbital mechanics supplies deceleration, and indeed the orbiter will have to fire its jets downward to maintain its closing rate. Normal shuttle rendezvous operations use V-bar approaches (closing from ahead), and the LDEF retrieval used a minus-R-bar approach (closing from above), but all of those involve jet firings in the general direction of the target; this is not a problem with small targets (which fit between the danger areas from the forward and aft thrusters), and large targets can be protected somewhat by using "low-Z" braking with thrusters angled away from the target, but very large targets with lots of fragile solar arrays present problems even so.
The main objective of the Atlantis test approach will be to determine how much fuel is used and whether the approach can be completed promptly (important because the Russian controllers would like to have the whole approach occur while they have radio contact with Mir).
Another minor objective on this flight will be testing of new recumbent seats for the orbiter middeck, intended to ease reentry and landing loads for Norm Thagard and his cosmonaut companions, who will come down on Atlantis next May after several months in free fall aboard Mir.
Sixty-four US senators write to Commerce Secretary expressing concern over the export license for Eyeglass, citing concerns that Saudi Arabia (which is still legally at war with Israel) will acquire unrestricted access to 1m images of Israel.
Endeavour lands at Edwards 11 Oct (KSC was socked in) after SRL-2 mission. The radar imaging was very successful, including the interferometry work, with some repeat passes coming within 26ft vertically and 149ft horizontally of the earlier ones. Early results from Mammoth Mountain (California) show where the Long Valley caldera's floor has swelled a few centimeters with reviving volcanic activity; geophysicists have spent years getting similar results for a handful of points in Long Valley, but interferometry combining the SRL-1 and SRL-2 radar data has generated a complete map of the changes. More orthodox comparison of radar images has confirmed that SRL-1 saw the seasonal flooding in the Brazilian rain forest (through the vegetation). Researchers would very much like to see a third SRL flight, and preferably a fourth, to build up a longer set of data and examine other seasons.
NASA asks National Academy of Sciences to recommend where to go next on space radar work, and specifically whether SRL should fly again and if so, whether it should be on the shuttle or as a permanent free-flyer. Also on the NAS panel's agenda is whether there is potential for doing a major radar satellite as an international project, combining current programs in the US, Canada, Europe, and Japan.
Procurement reform act (signed by Clinton last week) authorizes NASA to experiment with soliciting bids for mid-range contracts ($25k-$500k per year with a five-year total of at most $2.5M) over the Internet. Such contracts are 11% of NASA's spending but 80% of its contracts, and there is wide agreement that the current paperwork procedures (e.g., announcing through the Commerce Business Daily) are wasteful. New mid-range contracts will be solicited via both CBD and the Internet for six months starting (probably) in the spring, after which, if all is well, use of the CBD will be phased out. Not only is the Internet quicker than paper publication, it also allows potential bidders immediate access to all the details (the CBD only publishes summaries). One criticism has been made: "the Internet is not free". The response: "neither is the Commerce Business Daily".
Shuttle managers start comprehensive review of possible cost savings, in the wake of budget cuts. The flight rate (7/year) is to remain unchanged, the ET and SRBs are exempt because they have recently had major reviews, and closing one of the two shuttle launch pads has already been rejected. The idea of mothballing Columbia (oldest and heaviest of the orbiters) is being raised again, but it probably won't be done: the other three are committed to space-station assembly, leaving only Columbia to fly any non-station missions during that time.
NASA has decided to spend a small amount to build a kit for modifying a second orbiter -- Discovery -- for Mir missions. Current plans are for seven Mir flights, which Atlantis can handle, but three more are pencilled in as a hedge against difficulties, and flying them would require another orbiter. Building the kit now will make it quicker and easier to modify Discovery if the need arises.
NASA HQ overrules MSFC, going along with JSC in its request that the new SSME oxidizer turbopump be flown first on only one of the three engines. Mission 70 (Discovery, next June) will fly with one of the new Pratt & Whitney pumps, and if that goes well, 73 (next fall) will fly with all three engines converted. MSFC argued that ground testing would establish whether the pump was safe to fly, and it should therefore fly on all three engines to gain experience quickly; JSC countered that flight-testing it once before depending on it was smarter.
NOAA-11, the current "afternoon" civilian polar-orbit weather satellite, lost its high-resolution radiometer in mid-Sept due to electronics failure in the scan-motor power supply. The spacecraft was launched in 1988 and is well beyond its rated lifetime, and in fact its replacement was already slated for 4 Dec launch. The major impact will be loss of data on fine particles in the atmosphere, which is used to correct atmospheric data from other sources. Sea-ice tracking will also suffer, as will tracking of volcanic ash plumes for aviation. Major weather forecasting mostly uses the atmospheric sounder instrument, which is unaffected. NOAA-12's radiometer is unable to fill in completely for NOAA-11's, because its infrared channel has a higher noise level than 11's did.
There is more to life than getting a job | Henry Spencer and making a living. --Barbara Morgan | henry@zoo.toronto.edu