Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Wed, 1 Nov 89 01:27:58 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 1 Nov 89 01:27:35 -0500 (EST) Subject: SPACE Digest V10 #181 SPACE Digest Volume 10 : Issue 181 Today's Topics: Re: Magellan Temperature Re: Galileo Schedule Uplink schedule (Forwarded) NASA Headline News for 10/25/89 (Forwarded) STS-34 flight crew press conference scheduled (Forwarded) Mach - what does it really mean? Re: Balloon Launch attempt of a High Power Rocket (40 Miles). Magellan Status for 10/25/89 (Forwarded) ---------------------------------------------------------------------- Date: 26 Oct 89 03:23:15 GMT From: pgf@athena.mit.edu (Peter G. Ford) Subject: Re: Magellan Temperature In article <1989Oct25.204129.9586@cs.rochester.edu> quiroz@cs.rochester.edu (Cesar Quiroz) writes: >What happened to the temperature problem? I seem to have missed the >resolution. Magellan has experienced several temperature problems, each with a specific solution or work-around: [1] High temperature at nozzle of Venus orbit injection motor. Solved by pointing the spacecraft so that the sun never shines directly up the nozzle. Once in orbit, the motor is tossed away, the problem with it. [2] High temperatures at the nozzles of attitude control motors that have been exposed to direct sunlight for extensive periods. Ground tests with spare motors show that the temperatures won't harm the motors but they will cause the hydrazine fuel to pre-ignite before it hits its catalyst and make the performance erratic. The work-around is to "purge" a hot motor with a very small burst of fuel immediately before using it. [3] High temperatures in the equipment bay containing the attitude control electronics when that bay is illuminated by direct sunlight. The workaround is two-fold: 1) slowly rotate the spacecraft so that no one side remains in sunlight for too long, and 2) tilt the solar panel arrays so that they receive less than their maximum exposure to sunlight (the panels were producing more electrical power than the spacecraft could use, the excess being shunted into a large resistor which was, in turn, heating the spacecraft itself.) The bottom line is that the thermal problems don't look particularly serious. There is more worry about the effect of the very active Sun on the attitude control system -- solar protons hitting the star-sensing telescope produce intense flashes of light that interfere with the pointing accuracy. This problem is still being worked on -- the current thinking is that the on-board computers can be programmed to analyze the star-sensor signals and reject the spurious ones. I'm sure you'll be hearing more about this in the regular Magellan bulletins. Peter Ford MIT & Magellan Project ------------------------------ Date: 25 Oct 89 19:04:35 GMT From: uhccux!goldader@ames.arc.nasa.gov (Jeff Goldader) Subject: Re: Galileo Schedule In article <1989Oct25.153600.7715@rpi.edu> kyriazis@plato.rdrc.rpi.edu.UUCP (George Kyriazis) writes: > >My question is: How much memory does Galileo have? If it plays back >the pictures from Venus after it gets rid of its influence, it must >be some time, and assuming that it takes several pictures, where does >it store all this information? > >That brings the question of the resolution of the pictures, and how >many primary colors (if any) are there for each picture. Can anybody >answer that? > Galileo will store the Venus data on its tape recorder, which has a capacity of 900 Mbytes. The amount of data it can gather at Venus is limited by this capacity. Here are some numbers for the imaging system I pulled out of the latest Aviation Week: The wide-field camera uses a 1.5m f/8.5 Richey-Chretien telescope, just like Voyager's. The narrow-angle telescope also has the same specs as Voyager, but Av Week didn't list those. The detector is an 800x800 charge-coupled device (aka CCD) which is sensitive to wavelengths of 4000-11000 Angstroms. There are seven filters. All images are black- and-white, but color images can be put together from several different filters. The field of view is 0.47 degrees, and the pixel resolution is 10 microradians. Jeff Goldader University of Hawaii goldader@uhccux.uhcc.hawaii.edu Institute for Astronomy "So, Lonestar, now you see that Evil will always win- because Good is stupid." -The Dark Lord Dark Helmet, _SPACEBALLS_ Disclaimer: The University of Hawaii and the Institute for Astronomy neither support nor are in *any way* responsible for these opinions. ------------------------------ Date: 25 Oct 89 20:32:35 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Uplink schedule (Forwarded) LMD October 25, 1989 ATTENTION SATELLITE NEWS COORDINATORS SATELLITE FEED DATE: WEDNESDAY, NOVEMBER 1, 1989 UPLINK TIMES: 1:00 PM EST - KU BAND "G" STAR 2 2:30 PM EST - SATCOM F-2R RUNNING TIME: 14:30 SATELLITE COORDINATES KU Band "G" Star 2 - Orbital Position 105 degrees west longitude, transponder 7. Uplink frequency 14396 Vertical - Downlink frequency 12096 Horizontal. Audio 6.2 and 6.8 MHZ. Two Playbacks, both audio tracks each feed. Satcom F-2R - frequency "C" band - orbital position: 72 degrees west longitude - Transponder 13, frequency 3960.0 MHZ vertical polarization. Audio 6.8 MHZ. Due to single track audio playback capability, program will be uplinked twice. The first playback, channel 1 is a fully mixed track with narration, actualities, music and effects. The second playback immediately after the first, channel 2, is effects and actualities only. THE FOLLOWING 4 NEWS FEATURES WILL BE UPLINKED: "Combating Malaria" - NASA scientists are experimenting with remote sensing techniques which could make it possible to determine where the highest concentration of malaria transmitting mosquitoes are likely to occur. "Voyager's Last Encounter" - This feature will focus on what the spacecraft revealed about the planet now that scientists have had a few weeks to analyze the data. "Better Airplane Wings" - A Lear Jet and an F-106 are being used by researchers to investigate ways of improving the performance of airplane wings. "Sights and Sounds of Space" - Jane Ira Bloom, a saxophonist and composer wrote and composed music commemorating the return to flight of the space shuttle. She joined a team of artists commissioned to document the U.S. space program. NASA CONTACT IS: J.L. HEADLEE (XXX)YYY-ZZZZ ------------------------------ Date: 25 Oct 89 20:25:18 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 10/25/89 (Forwarded) ----------------------------------------------------------------- Wednesday, Oct. 25, 1989 Audio: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Wednesday, October 25th...... Technicians at Dryden Flight Research Facility report that the orbiter Atlantis sustained minimal tile damage during its just completed flight. An initial inspection shows that no tiles are missing, and overall about 25 dings were reported on the orbiter's lower surface. The reinforced carbon-carbon chin panel also was reported in good shape and will not have to be removed prior to Atlantis' next flight in February. The tires and brakes have been removed. Normal scuffing was observed on the tires and no damage was reported on the brakes. The current processing schedule calls for Atlantis to return to Kennedy Space Center aboard the 747 shuttle carrier on Saturday. At KSC...wind and rain this morning forced the postponment of rollout of the orbiter Discovery to the launch pad. The move is now scheduled to begin tomorrow morning at 12:01 Eastern time. Discovery's crew is scheduled to fly into KSC on Saturday, to participate in a two-day launch countdown rehearsal which begins Sunday morning. They will fly a classified DoD mission later next month. Aerospace Daily reports the compromise $12.4 billion NASA budget for FY '90 goes to the Senate floor today. The House has not yet scheduled debate on the measure. And the Daily reports...the House Space, science and Technology Committee has scheduled two days of hearings next week on NASA's rephasing program for Space Station Freedom. The committee wants to review the affect of rephasing on commitments to international partners. *********** ----------------------------------------------------------------- Here's the broadcast schedule for public affairs events on NASA Select television. All times are Eastern. Thursday, Oct. 26...... 7:00 A.M. Roll out of the orbiter Discovery to launch pad 39-B. 11:30 A.M. NASA Update will be transmitted. All events and times are subject to change without notice. ----------------------------------------------------------------- These reports are filed daily, Monday through Friday, at 12 noon, Eastern time. ----------------------------------------------------------------- A service of the Internal Communications Branch (LPC), NASA Headquarters, Washington, D.C. ------------------------------ Date: 25 Oct 89 20:27:00 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: STS-34 flight crew press conference scheduled (Forwarded) Sarah Keegan Headquarters, Washington, D.C. October 25, 1989 Jeff Carr Johnson Space Center, Houston, EDITORS NOTE N89-71 STS-34 FLIGHT CREW PRESS CONFERENCE SCHEDULED The STS-34 astronaut crew will meet with news media at the Johnson Space Center, Houston, on Wednesday, Nov. 1, to discuss the recent mission to deploy the Jupiter probe, Galileo. The event will begin at 2 p.m. EST, and consist of a slide and video presentation by the astronauts, followed by questions. News media are invited to participate at JSC in Building 2, room 135, or via two-way audio from NASA Headquarters, Washington, D.C., the Kennedy Space Center, Fla., the Marshall Space Flight Center, Huntsville, Ala., or the Jet Propulsion Laboratory, Pasadena, Calif. Live NASA Select television coverage will be carried on Satcom F2R, transponder 13, C-band, at 72 degrees W. longitude, 3960.0 MHz, 6.8 MHz. ------------------------------ Date: 25 Oct 89 19:49:22 GMT From: ksr!clj@uunet.uu.net (Chris Jones) Subject: Mach - what does it really mean? One of my pet peeves is the use of Mach numbers in space flight contexts. As I understand it, Mach 1 is the speed of sound (under ambient conditions, I would guess). I understand the usefulness of saying that something is going more or less than the speed of sound, since aerodynamic characteristics change passing through that speed, but hearing that the shuttle enters the atmosphere at, say, Mach 24 is so much hooey in my opinion. What does it mean when I hear some NASA spokesperson say that? Since the speed of sound depends on temperature, pressure, and composition of medium, what does it mean when I read in AW&ST (October 9, 1989, p. 109) that the Titan probe released from the Cassini mission will end its entry phase at a velocity of about 1.5 Mach? What's wrong with m/sec or some similar "real" unit? (Yes, I've read one answer to the question posed in my subject. I'm not really sure messages are crufty hacks...) ------------------------------ Date: 25 Oct 89 17:02:53 GMT From: mailrus!jarvis.csri.toronto.edu!db.toronto.edu!hogg@g.ms.uky.edu (John Hogg) Subject: Re: Balloon Launch attempt of a High Power Rocket (40 Miles). In article <37959@looking.on.ca> brad@looking.on.ca (Brad Templeton) writes: >But what good is a baloon rocket launch? When it comes to getting into >orbit, 90% of the problem is gaining horizontal velocity, not going through >the atmosphere or gaining altitude. Yes, but the launch described was sub-orbital, and the balloon seems to have roughly doubled its altitude. From the description given, the project is hobby rocketry on an enthusiastic scale, so maximum altitude is a goal in itself. However, the performance boost could also be very welcome if the rocket were used simply as a vehicle. Atmospheric studies can gain by looking at more atmosphere, and a lofted launch would be a real boon to microgravity work. Once the vehicle falls back into ``substantial'' atmosphere, the micro-g ride is over. For vehicles with marginal performance, a balloon launch may be necessary to get any clean microgravity at all. Not all rockets go into orbit. (Not even all peaceful rockets.) There's a real market out there for up-and-down trips. The American start-ups are using this fact to climb into the market incrementally, and old hands (such as Bristol Aerospace in Winnipeg) have been selling rockets like the Black Brant for many years. -- John Hogg hogg@csri.utoronto.ca Department of Computer Science, University of Toronto ------------------------------ Date: 25 Oct 89 20:22:40 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Magellan Status for 10/25/89 (Forwarded) MAGELLAN WEEKLY STATUS Oct. 25, 1989 This is the weekly Magellan status report. Magellan on Tuesday, Oct. 24, reached the point in Venus' orbit where the planet will be next Aug. 10. So it has one more orbit around the sun before orbit insertion. The spacecraft is 75,911,294 miles from Earth. Having passed through perihelion on Oct. 7, Magellan is slowing as it begins its return to the orbit of Earth and is now traveling at a speed of 84,455 mph relative to the sun. The one-way light time is 6 minutes and 48 seconds. Magellan is operating without major problems as it begins the second third of its cruise, moving away from the sun. Only two of the scheduled seven star calibrations performed last week were fully successful. All others had only a partial attitude update from one star due to spurious interrupts from increased solar activity. Another major solar flare on Oct. 19 does not bode well for the coming week's starcals. The good news is that the flight software patch to alleviate the problem with a filter passed its first test in the System Verification Laboratory. In conference with Kearfott, the gyro manufacturer, it was determined the most likely cause of the erratic behavior of both current and temperature on gyro B2 is vibration of the main bearing retaining ring at low temperatures. The analysis is preliminary, and is continuing. Kearfott believes that since all excursions of the telemetry values are well within specification limits, there would be no attitude problem if mission operations is forced to return to it. A backup gyro is currently being used. SPACECRAFT Distance from Earth (mi) 75,911,294 Velocity Geocentric 64,036 mph Heliocentric 84,455 mph One-way light time 6 mins, 48 secs ------------------------------ End of SPACE Digest V10 #181 *******************