henry@utzoo.uucp (Henry Spencer) (11/27/89)
Editorial commenting that despite protestations of "strong support", Bush, Quayle, and the National Space Council have been silent while NASP has been fighting for its life in budget hearings. DARPA is examining a proposal by Globesat Inc and CTA Inc for a small tactical spysat, capable of launch on Pegasus or other small boosters, that could provide 1m resolution from a 400nmi orbit. The concept is to give the armed forces a low-cost quick-look reconnaissance capability. Latest on the Incredible Shrinking Space Station... Completion will slip 18 months to 1999 and management will be reorganized, again. More of the management authority will move to Marshall and Johnson. Launch of the Japanese and European modules will slip about a year to 1998. Electric power available to users drops from 45kW to 30kW. The oxyhydrogen thruster scheme has been abandoned in favor of hydrazine; this will be a simpler system and will not need 4kW of power for water electrolysis, but will need regular fuel shipments from Earth. The 20kHz AC power system is abandoned [good!] in favor of DC. [Curious -- why not use the standard aircraft 400Hz AC? Because that would be an admission that the ridiculous 20kHz stuff was a mistake?] The thermal control system is being redesigned and simplified. The combined effect of several of these changes is to eliminate the need for a major external plumbing network, which will simplify assembly. The 8psi spacesuit is deferred in favor of using the 4psi shuttle suit (which requires a substantial prebreathing period before use). These changes were formally recommended to Truly by Lenoir (associate admin for Space Station and Spaceflight) last week. [Readers are reminded that all times in these summaries are as of publication date.] Lenoir was not impressed by the state the program was in when he took over: "I had hoped I would find the program in better shape..." He wasn't impressed by the management setup either: "There were certainly more efficient ways to segment this program..." The international partners are considering their reactions, but overall they are not pleased. Congress is also starting to grumble about the continued shrinkage and slippage of the program. SDI flies two sounding-rocket tests Sept 4 and 11 to validate laboratory data on survivability techniques. Few details available. NASA assesses water damage to Columbia after accidental activation Sept 24 of a fire-extinguisher water-deluge system. [Eventually assessed as not serious.] The payload bay doors, and most other doors, were closed at the time, and the orbiter was powered down. It has been powered up without incident, although there is some remaining worry about wet connectors that might short. LDEF is just above 200nmi. If Columbia goes up on schedule Dec 18, LDEF will be retrieved Dec 21 at a predicted altitude of 177nmi. Solar activity of late is nearly 25% above prediction, however. NASA would be reluctant to attempt retrieval below 130nmi. Last NASA-run KSC expendable launch successful Sept 25, carrying a Navy comsat, after a 3-day slip due to concern about Hurricane Hugo. -- That's not a joke, that's | Henry Spencer at U of Toronto Zoology NASA. -Nick Szabo | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
mikec@ux1.lbl.gov (Mike Chin) (11/28/89)
In article <1989Nov26.223357.27453@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >but will need regular fuel shipments from Earth. The 20kHz AC power >system is abandoned [good!] in favor of DC. [Curious -- why not use the >standard aircraft 400Hz AC? Because that would be an admission that the >ridiculous 20kHz stuff was a mistake?] The thermal control system is being Why is 20 kHz bad? I vaguely remember an article in Powertecnics describing this system, but I wasn't aware of any controversy. I was involved in a Explorer sat project where all voltages were derived from a 28V bus; designing the DC-DC converters was a major effort (luckily not done by me). Mike Chin Lawrence Berkeley Labs MJChin@lbl.gov
henry@utzoo.uucp (Henry Spencer) (11/28/89)
In article <4300@helios.ee.lbl.gov> mikec@ux1.lbl.gov (Mike Chin) writes: >Why is 20 kHz bad? I vaguely remember an article in Powertecnics describing >this system, but I wasn't aware of any controversy. The 20kHz power system was bad because it was new technology for the sake of new technology, instead of new technology for the sake of a working space station. It did promise some modest improvements in weight. In return, it demanded that all power equipment be developed from scratch, specially for the space station. Not even the light bulbs would be standard. The obvious alternative -- use 400Hz aircraft systems -- would have been slightly heavier but vastly cheaper, because much of the hardware could be had off the shelf and all the design issues were fully understood. >I was involved in a Explorer sat project where all voltages were derived >from a 28V bus; designing the DC-DC converters was a major effort (luckily >not done by me). I agree that the switch to DC sounds dumb, although I haven't seen a detailed technical explanation of the tradeoffs. As I said, I suspect it's a face-saving maneuver for someone. -- That's not a joke, that's | Henry Spencer at U of Toronto Zoology NASA. -Nick Szabo | uunet!attcan!utzoo!henry henry@zoo.toronto.edu