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 ; Sun, 18 Nov 1990 02:17:51 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 18 Nov 1990 02:17:15 -0500 (EST) Subject: SPACE Digest V12 #570 SPACE Digest Volume 12 : Issue 570 Today's Topics: Re: Pity The Much Abused Shuttle Re: CRAF/Cassini Update - 11/09/90 ELV Launch Loads Re: LNLL Inflatable Stations Re: Spectacular event over Europe Galileo Update #2 - 11/16/90 Re: Pity The Much Abused Shuttle Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: Fri, 16 Nov 1990 13:00-EST From: Barak.Pearlmutter@CS.CMU.EDU Subject: Re: Pity The Much Abused Shuttle In regards to the comments by hydra!francis (Francis Vaughan): > Just how proof to an air launched guided sat-killer missile do you think > the shuttle is? Sitting duck is the term that comes to mind. It can't even > run. > > At boarding range a high velocity rifle could cripple the shuttle in > a minute. Just loose a few of those nice tiles in critical places and > its a goner on reentry. Let alone what would happen if you disabled > any of the host of critical systems. You could nearly kill the shuttle with > a slingshot and a well aimed rock. Your "unable to run" argument is fallacious; putting propellant in the cargo bay and carrying it into orbit would make the shuttle extremely maneuverable. I think you're overestimating the shuttle's vulnerability to light arms; I doubt a burst from an uzi would do any serious damage. But in any case, doesn't your vulnerability argument apply to a Jeep too? Jeeps are unarmored. One shot from a pistol could disable a Jeep. Yet for some reason Jeeps are useful military vehicles. > " Is the satelite in the enemy shuttle cargo bay Igor?" > > "Yes Ivan" > > "Activate the self destruct Igor" It would certainly be prudent to disable or jam an enemy satellite's communications facilities before bringing it aboard. ------------------------------ Date: 16 Nov 90 18:27:37 GMT From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: CRAF/Cassini Update - 11/09/90 I wrote: >...not a good place for solar power. You have the usual annoying problem >of it being night half the time, but the real killer is the dust storms, >which can cut surface illumination to nearly zero for months at a time. Some correspondence with folks in a position to know indicates that the latter is a bit of an overstatement. There is still a fair bit of light, as it turns out, although it may well be inadequate for viable solar power. -- "I don't *want* to be normal!" | Henry Spencer at U of Toronto Zoology "Not to worry." | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 14 Nov 90 02:59:55 GMT From: swrinde!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@ucsd.edu (Wales Larrison) Subject: ELV Launch Loads Allan, you had asked for typical launch loads for different launch vehicles. The following data was produced from the vehicle "User Handbooks" for a project looking at launching a payload on different vehicles. Launch vehicle vibration induced accelerations are combined with launch vehicle steady state accelerations to produce spacecraft design load factors (i.e., accelerations that must be considered for spacecraft structural design). These load factors are a function of both launch vehicle characteristics and spacecraft dynamics. Therefore it is necessary to design the spacecraft so the dynamic coupling between spacecraft and launch vehicle low frequency modes is avoided. Minimum lateral mode frequencies should be above 10 Hz. Minimal axial mode frequencies differs for all ELVs (I didn't want to transcribe several tables) and varies from 15 Hz for the Atlas to 31 Hz for the Ariane. Note the following data includes no design margins. A margin of 1.4 is typical for design purposes. (Negative indicates compression in axial loads - units in standard G's) Axial Lateral Atlas -6/+2 -2/+2 Titan III -7/+3 -2.5/+2.5 Titan IV -6.5/+3 -3.5/+3.5 Delta II -6.5/+0 -2.5/+2.5 Ariane IV -7/+2.5 -2.5/+2.5 Proton -4/0 -3/+3 Shuttle -3/+0 -1.0/+1.0 Shuttle Emergency -3.5/+2.0 -3.7/+3.7 [1] Note [1]. Shuttle emergency lateral loads are driven for emergency landings - assuming a heavy orbiter "slapping" down hard on its landing gear and slamming on its brakes. Normal, measured landing G's are usually less than 0.5 G lateral and axial. Note [2]. ELVs also have to design to typical "pyro shock" load of1500-2500 G/sec which occurrs when the explosive bolts on the payload shroud separate, and more severely, when the pryo separation devices go off to separate the payload from the ELV. Shuttle payloads typically use a spring system for separation from the vehicle (IUS, PAM) or electrically driven latches (LDEF, Space Telescope, SPAS, etc), or a combination of the two. Shuttle pryo shock levels during ascent are in the vicinity of 500 G/sec or less from SRB and ET separation, which are intentionally attenuated or dissipated through the structure. Last set of random comments. You could probably use an ELV for launch, assuming you had a trained, willing and well-conditioned young crew, and equipped the ELV with a launch escape tower. F-16 pilot trainees are centrifuge tested to 6 Gs for a period of a few seconds, so 8 G's or so should be tolerable for few minutes ( Just don't ask them to do much for an while afterwards....) Does anyone remember the loads imposed by the Apollo launch escape system? I remember the Gemini had very high-G ejection seats (they were rumored to be a guarantee of back injury if used - and were only to be used if the choice was quick death rather than slow death). How about the Mercury escape system loads? Soyuz? Also, does anyone have any particulars on the "Little Joe" program at White Sands which qualified the Apollo launch escape system? I seem to remember about a half-dozen or so suborbital tests, including several failures. Anybody have costs of that? ---------------------------------------------------------------- Wales Larrison Space Technology Investor -- Wales Larrison Internet: Wales.Larrison@ofa123.fidonet.org Compuserve: >internet:Wales.Larrison@ofa123.fidonet.org -------------------------------------------------------------------------- ------------------------------ Date: 16 Nov 90 19:29:48 GMT From: rochester!sol!yamauchi@louie.udel.edu (Brian Yamauchi) Subject: Re: LNLL Inflatable Stations In article <9011161824.AA13862@iti.org> aws@ITI.ORG ("Allen W. Sherzer") writes: In article <46667@eerie.acsu.Buffalo.EDU> you write: >>>You would have little chance of retrieving something if it was >>>dropped or came unhooked. >>Depends on how valuable it was. I'm sure hand tools would be left but >>astronauts would be retrieved. >Correct me if I'm wrong, but the astronauts (and tools) would be >awfully hard to catch up to to bring back. > >[calculations showing astronaut flying away at 50ft/sec deleted] These numbers look good to me. I guess we will need to tie him to the ladder :-). I suppose you could use clamps like the ones mountain climbers use to attach themselves to their lines. Of course, it would still be possible to fall while moving. I was thinking we could save weight by using an umbilical to connect the astronaut to the life support system. Perhaps we can make the umbilical strong enough to support him/her should they fall off. My guess would be that such an umbilical would be much too cumbersome. You would also have to worry about getting the line snagged on something and developing a tear. >I really do like the idea of a spun station, but either: > a) despin the station for EVAs or > b) give the astronauts MMU's to get back! I think MMU's would be out of the question. They would weigh too much at the lower levels. Also, MMU's require too much maintenance. How about bungey cords like the kind they use to jump off bridges? Yow! All sorts of bad cartoon images spring to mind :-). The astronaut playing "snap the whip" with the station (and losing). The astronaut being slammed from one module to another like a giant paddle ball. The astronaut's cord getting tangled around the hub and the astronaut spiraling in, in smaller and faster circles until *SPLAT*. A better idea might be to use something like the EVA Retriever being developed for Freedom. This is a robot which is designed to pick up things that fall off the station -- like tools and astronauts. The advantage is that it can be deployed immediately to fetch the target -- you don't have to wait for another astronaut to suit up. It uses a modified MMU, but at least you only need one, and weight is not a factor since (1) it's a robot and (2) it can stay at the hub until it is needed. -- _______________________________________________________________________________ Brian Yamauchi University of Rochester yamauchi@cs.rochester.edu Computer Science Department _______________________________________________________________________________ ------------------------------ Date: 16 Nov 90 11:24:31 GMT From: mcsun!unido!mpirbn!p515dfi@uunet.uu.net (Daniel Fischer) Subject: Re: Spectacular event over Europe In article <816@obs.unige.ch> pfenniger@obs.unige.ch writes: >A spectacular event occurred on Nov. 5, around 18h UT (19h local time) over a >large part of western Europe. Something similar to a big meteorite or >satellite atmospheric reentry has been observed by thousands of people [...] >Could someone with connection to NASA, NORAD tells if the satellite hypothesis >can be rejected ? Such a large orbiting object should have been tracked.[...] It *was* a reentry: NORAD has distributed the news that the event was caused by the reentry & burnup of the upper stage of the rocket that carried the Soviet comsat GORIZONT 21 into orbit on 3 October. Experienced observers on the ground had guessed that fact already from the long duration of the phenomenon, 2 to 3 minutes: even a really big meteor (like the one from 1972 or the recent Euro- meteor from Sept.1986) crosses the sky in a few seconds. [Sources: communication with D.Heinlein, Europ. Net for Meteor Cameras + AP] ------------------------------ Date: 16 Nov 90 21:55:14 GMT From: csus.edu!wuarchive!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucdavis.ucdavis.edu (Ron Baalke) Subject: Galileo Update #2 - 11/16/90 GALILEO STATUS REPORT November 16, 1990 As of noon (PST) Thursday, November 15, 1990, the Galileo spacecraft is 11,584,870 miles from the Earth and traveling at a heliocentric speed of 60,140 miles per hour; distance to the Sun is 101,784,750 miles (1.09 AU). Round trip light time is 2 minutes, 8 seconds. The sequence commanded flushing maneuver is in process as planned. This is the 21st flushing maneuver executed since launch. Later today the spacecraft will execute a sun pointing maneuver of approximately 12.5 degrees. A non-interactive command was sent on November 9 to reset the EPD (Energetic Particles Detector) LEMMS detector threshold to its normal low setting. The previous day, the threshold was increased in response to high noise counts. Subsequent monitoring of the detector performance indicated proper operation and allowed a safe return to the lower threshold setting. A special EUV (Extreme Ultraviolet Spectrometer) memory readout was performed on November 10 in response to anomalous operation observed after commanding the instrument to the encounter mode. The MRO (Memory Read Out) revealed two bits of a single byte were corrupted. The memory corruption is similar to that observed during last December's 4-day science checkout although at a different memory location. The latest anomaly was recreated and verified on the EUV simulator at the University of Colorado. The cause of this EUV anomaly and the previous December anomaly is being investigated vigorously. Commands were sent on November 13 to "patch" the corrupted memory location and reset it to its proper state compatible with Earth encounter data collection and proper instrument operation was restored. A NO-OP command was sent on November 12 to reset the Command Loss Timer to 216 hours, the planned value for this mission phase. The TCM-7 (Trajectory Course Maneuver) sequence memory load was successfully transmitted to the spacecraft on November 12. The spacecraft properly executed the maneuver on November 13. The maneuver was comprised of one axial segment and one lateral segment. Spacecraft performance throughout the maneuver activity was excellent. The RPM (Retro Propulsion Module) tank pressure and thruster temperatures were near predicted levels; temperatures were similar to those observed in TCM-6. No spin rate correction was required between the axial and lateral burn segments or at the end of the maneuver activity. Attitude pointing perturbation was minimal beginning at about 5 mrad and growing to almost 8 mrad after the axial segment. This pointing error was corrected with a sequence planned pointing correction to near 0.5 mrad. The lateral burn segment produced about 0.8 mrad of attitude pointing perturbation, well below the 2 mrad threshold, and consequently the sequence planned pointing correction was not performed. Preliminary radio frequency navigation data indicates an axial and lateral overburn of about one percent which is near pre-maneuver execution predictions. Four delta DOR (Differential One-way Ranging) navigation activities were completed this week - two on November 12 and two on November 15. The delta DOR activities were successful. A total of 23 of the planned 27 delta DOR activities are complete; 19 were successful. The PPR (Photopolarimiter Radiometer) instrument was powered on November 14. Instrument operation is normal; power and thermal profiles are within predicted levels. The PPR calibration scheduled for this morning was completed as planned. There were no unexpected events; data is being analyzed. The AC bus imbalance measurement dropped about 2 DN (.4 volt) and is stable near 48.2 volts. DC bus measurement is presently reading about 2 volts. Both AC and DC changes occurred during periods of no spacecraft load switching. Very little (1-2 DN) AC/DC bus measurement change was observed during the TCM-7 execution. All other power-related and spacecraft telemetry measurements are normal. The final Project GDS (Ground Data Systems) test for Earth 1 was successfully completed with the Canberra 34 meter and 26 meter stations on November 13. A key objective was met with the successful test of the probe data flow from the tracking station to the Probe Flight Operations Equipment (PFOE) in the Galileo Mission Support Area (MSA). This link is required to support the Probe checkout scheduled for December 4th. GDS testing has now validated all GDS functions required for Earth 1 support. The DSN (Deep Space Network) and Project Flight Team personnel participated in a "walk-through" rehearsal of the Earth Closest Approach (ECA) operations on November 15th. During the review several minor changes to the sequence of events were suggested and accepted by the Flight Control and Support Office. This walk-through will be repeated next week. The LGA-2 (Low Gain Antenna-2) retraction and HGA (High Gain Antenna) deployment reviews were held on November 14 and 15, respectively. No concerns/discrepancies were identified by the review board between expected flight conditions and ground test data. Expected flight conditions are well within the ground test database. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 16 Nov 90 21:02:57 GMT From: mojo!SYSMGR%KING.ENG.UMD.EDU@mimsy.umd.edu (Doug Mohney) Subject: Re: Pity The Much Abused Shuttle In article <658778464.bap@F.GP.CS.CMU.EDU>, Barak.Pearlmutter@CS.CMU.EDU writes: >Your "unable to run" argument is fallacious; putting propellant in the >cargo bay and carrying it into orbit would make the shuttle extremely >maneuverable. And a bigger target. Remember, you *have* to open the cargo bay doors in orbit (All that internal heat which needs to be radiated. Of course this makes a wonderful signature for an IR homer missile, personified by several cheap, light-weight models in your choice of man-portable or luggable by spacecraft). Now, you could armor your extra propellant tanks (which, by the way, they are JUST getting qualified to even put into the system), but armor is weight. Weight is bad if you are putting something into orbit. >I think you're overestimating the shuttle's vulnerability to light arms; >I doubt a burst from an uzi would do any serious damage. But in any >case, doesn't your vulnerability argument apply to a Jeep too? Jeeps >are unarmored. One shot from a pistol could disable a Jeep. Yet for >some reason Jeeps are useful military vehicles. Wrong Bbbbbuck. Shooting out the windshield on a jeep results in lots of glass and maybe you might kill someone. If you're Rambo, you dive out of the jeep, tastefully tuck-and-roll, then return fire. If the windshield of the shuttle gets shot out, and you don't happen to be wearing a space suit, you suck vaccuum. Should you be so fortunate enough to get into a space suit, Ivan-the-Terrible has now boarded the shuttle to finish the job he started. But, hey, why use GUNS. A couple of handfuls of BBs or gravel (preferably gravel, it won't show on radar) dropped into the orbital flight path and major damage to the system... If you're real lucky, you get a hit on the nice hydrozene tanks, thereby blowing a big hole in the bird when it goes up and generally assuring you are going to do some hitchhiking. >It would certainly be prudent to disable or jam an enemy satellite's >communications facilities before bringing it aboard. Sure. So what do you do when the Soviets declare war when you pick up their satellite? Shuttle orbital flight-paths are carefully tracked by their version of NORAD, and if one intersects with Spy-Sputnik, followed by Spy-Sputnik going off-line, don't you think someone might suspect something? Then the Soviets, determined to ruin your day, launch an SS-9 with ASAT warhead (or more probably something they have tucked away for a rainy day with solid fuel) and within 3-4 orbits turn the Rambo-Shuttle into scrap metal. ------------------------------ End of SPACE Digest V12 #570 *******************