Date: Thu, 14 Jan 93 05:05:22 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #044 To: Space Digest Readers Precedence: bulk Space Digest Thu, 14 Jan 93 Volume 16 : Issue 044 Today's Topics: DC-1 and the $23M NASA Toilet DC reentry Galileo Stuck Ribs / Remote Manipulator? (3 msgs) I want to be a space cadet NASA Graduate Student Summer Program needed: a real live space helmet Oxygen in Biosphere 2 Planets around nearby sun-like stars Railgun in Southwest US (2 msgs) russian solar sail?+ SNC meteorites Weekly reminder for Frequently Asked Questions list Who can launch antisats? (was Re: DoD launcher use) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Wed, 13 Jan 1993 18:00:37 GMT From: Henry Spencer Subject: DC-1 and the $23M NASA Toilet Newsgroups: sci.space In article <1j0668INNrai@mirror.digex.com> prb@access.digex.com (Pat) writes: >>... Urine is separated to be >>dealt with differently (dumped, I think); this is what has been done by >>all such systems, including the Skylab one. > >Uh, OH. I think we have a sci.space first here. >I get to correct Henry. Bill, Dennis watch this real careful, you'll >probably never see this again in this century. Well, possibly not, if this attempt is an example. :-) >I watched a NASA fiilm on Select late one night, where they discussed >the Skylab life support system. Skylab had three seperate water >recovery systems. identical in function and part. >Water was recovered from exhalation, urine and the shower/handbasin. >each system used a wick evaporator to distill h2o and then passed the >vapor through a carbon filter to remove odor and contaminants. Odd that this isn't mentioning in "Living and Working in Space", the NASA History book about Skylab (which has quite a bit of discussion of the waste-handling systems -- some of the detailed decisions about how to deal with urine were among the biggest controversies in the project). Nor is any of it mentioned in the Skylab News Reference (Hardware and Systems). Nor is any of it mentioned during a how-did-you-go-to- the-bathroom interview with Rusty Schweickart, who was on one of the backup Skylab crews. According to these references, which I am inclined to consider reliable, there was *no* water recovery from urine on Skylab (in fact, I didn't encounter mention of any water recovery at all -- Skylab was launched with three tons of water in its supply tanks). Urine from each crewmember was collected for 24 hours, a small sample was taken and frozen for biomedical analysis on the ground, and the bag containing the rest went into Skylab's trash airlock, thence into the S-IVB oxygen tank (which was vented to space, via filters to contain particulates). Sure they weren't talking about the system for the space station? I know they've put a lot of effort into making recycling work for the station. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 13 Jan 93 17:31:24 GMT From: "Edward V. Wright" Subject: DC reentry Newsgroups: sci.space In <1993Jan13.131228.12637@ke4zv.uucp> gary@ke4zv.uucp (Gary Coffman) writes: >I thought nose first re-entry was chosen because the rear of the >vehicle, with it's multiple engine bells and plumbing hanging out, was >not aerodynamically clean enough. I read that they were considering >using a rear entry when and if they switched to aerospike engines. >That would eliminate the tricky turnover maneuver at high Q. I'm sure that was a consideration also. Aerospikes do make a base-first reentry more attractive. But Max Hunter was considering nose-first reentry even before it was decided not to use an aerospike. He considers it the "more conventional" approach because most of our experience with reentry-vehicle design has come from missile programs. ------------------------------ Date: Wed, 13 Jan 1993 17:21:00 GMT From: David Pugh Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary In article <1993Jan13.064524.13581@mr.med.ge.com>, hinz@picard.med.ge.com (David Hinz (hinz@picard.med.ge.com)) writes: |> |> A co-worker of mine brought up an interesting question about the |> service problems such as we are seeing with Galileo. How feasable |> would it be to incorporate a robotic arm manipulator into these designs, |> articulated so that it could reach everything on the probe/satellite? ... |> What besides weight & cost would prohibit this? How much use would something |> like this get, and would it be worth it? One problem is that, for most problems, a manipulator would be of very little use. Galileo is a little unusual in that it is having problems with its external machinery rather than its internal electronics (such as Solar Max or Magellan), internal machinery (Voyager's camera platform). And, even in cases where the manipulator could reach, it's not clear it could do anything (I doubt, for example, that a manipulator could help damp the vibration in Hubble's solar panels as it moves from light to shadow & back). The real solution to problems like Galileo's is open and test everything in LEO, where you have some hope of fixing it if there is a problem. That was, I think, the initial plan for Galileo but it died with the Centaur upper stage. -- ... He was determined to discover the David Pugh underlying logic behind the universe. ...!seismo!cmucs!dep Which was going to be hard, because there wasn't one. _Mort_, Terry Pratchett ------------------------------ Date: 13 Jan 93 15:40:14 GMT From: fred j mccall 575-3539 Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary In <1993Jan13.064524.13581@mr.med.ge.com> hinz@picard.med.ge.com (David Hinz (hinz@picard.med.ge.com)) writes: >A co-worker of mine brought up an interesting question about the >service problems such as we are seeing with Galileo. How feasable >would it be to incorporate a robotic arm manipulator into these designs, >articulated so that it could reach everything on the probe/satellite? >This could be done with, perhaps, a variety of tooling, an articulated arm, >and a track around the device so it could reach wherever it needs to go, >such as, for instance, a stuck antenna rib. >Obviously, this would have a bit of weight to it, but I would think the cost >would be fairly reasonable compared to lost productivity & usability. If >you could just work the remote manipulator and fix the problem, that would >beat weeks/months of hammering or whatever. >What besides weight & cost would prohibit this? How much use would something >like this get, and would it be worth it? If we can't get an antenna to deploy properly, what do you think the odds are that such an arm would work? I also think you're talking about a lot more weight penalty than you probably think you are, what with having to be able to reach ANYWHERE on the vehicle, have sufficient strength to do the work, and sufficient dexterity to manipulate everything on the vehicle. I would say that it's simply not practical. -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Ames Dryden ------------------------------------------------------------------------------ Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me. ------------------------------ Date: 13 Jan 93 17:31:27 GMT From: "Peter J. Scott" Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary In article <1993Jan13.064524.13581@mr.med.ge.com>, hinz@picard.med.ge.com (David Hinz (hinz@picard.med.ge.com)) writes: > > A co-worker of mine brought up an interesting question about the > service problems such as we are seeing with Galileo. How feasable > would it be to incorporate a robotic arm manipulator into these designs, > articulated so that it could reach everything on the probe/satellite? This is rather reminiscent of the BIS Daedalus starship proposal (a serious study, well worth reading) which contained provision for robotic repair devices they called wardens to accompany the probe. But they had good reason to include them, made them much more robust and complicated, included several of them for redundancy, and assumed 21st-century technology for their construction. -- This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@euclid.jpl.nasa.gov) ------------------------------ Date: Wed, 13 Jan 1993 15:05:57 GMT From: gawne@stsci.edu Subject: I want to be a space cadet Newsgroups: sci.space In article , rabjab@golem.ucsd.edu (rabjab) writes: > I heard that the Air Farce now has a space command- is there now a > service academy like Annapolis where I can be a space cadet? While the Air Force may wish to claim space command as their own, it is in fact a joint service command staffed by folks from all DoD services. The USAF is the majority player at space command, but that's all. If you want to work there you have to go thru one of the existing service academies or a ROTC program. Then HOPE that someday all your wishes come true and you're assigned there. But you're more likely to find yourself on the ground tracking stuff in space, than in space yourself. US Space Command is considered a "combatant command", similar to the much more well known US Central Command (CENTCOM was the headquarters of Desert Shield/Storm, the made for TV war.) The Space Commander is (?) a 4 star billet, and I've heard it alternates between Air Force and Navy officers. Perhaps somebody who works for Space Command can confirm or refute this. Seems I recall somebody called "Fuzzy" who has contributed to our little group before who is associated with SC. -Bill Gawne, Space Telescope Science Institute ------------------------------ Date: Wed, 13 Jan 93 12:55:22 -0500 From: cohn@zephyr.meteo.McGill.CA Subject: NASA Graduate Student Summer Program > Subject: NASA Graduate Student Researchers Program - help >Greetings. I have just today found the 1991/1992 GSRP informational and >application packet, but I have been unable to reach anyone about getting >the 1993/1994 packet. The obvious phone numbers in this document are no >longer in service, and the deadline for proposal submission is 01 February. Quinn, I'm not sure this is what your after but EOS (Trans of the AGU) advertises the USRA/NASA GSFC Graduate Student Summer Program/Summer 1993) The program runs from 6/14 to 8/20. Application deadline is Feb 15. Contact is: Ms. Paula Webber USRA Student Programs Coordinator/GSSP Mail Code 610. Greenbelt, MD 20771 (301)286-5057 ------------------------------ Date: 13 Jan 93 17:24:28 GMT From: Edmund Hack Subject: needed: a real live space helmet Newsgroups: sci.space In article rabjab@golem.ucsd.edu (rabjab) writes: >When I want to feel like I'm in space lately I've been wearing a >large goldfish bowl over my head, but it bumps around too much >when I drive. Where can I buy a decent helmet or get one real cheap? >It must have earphones with little antennas coming out of them, >like the ones in Lost in Space. >Somebody told me there was a contest I could enter with cereal box >tops to win a spacesuit! But I can't find the cereal. It is a soap contest, not a cereal contest. Look for Skyways Soap. You have to write a slogan about why you like their soap. Try the slogan "Because it is as pure as the sky itsself!" You will win a spacesuit if you are the fifth? prize winner. Unless you are fully prepared, don't fix it up and walk around in the back yard calling "Junebug to Peewee!" > >HELP! >-rabjab -- Edmund Hack - Lockheed Engineering & Sciences Co. - Houston, TX hack@aio.jsc.nasa.gov - I speak only for myself, unless blah, blah.. "You know, I think we're all Bozos on this bus." "Detail Dress Circuits" "Belt: Above A, Below B" "Close B ClothesMode" ------------------------------ Date: Wed, 13 Jan 1993 15:07:08 GMT From: Brad Whitehurst Subject: Oxygen in Biosphere 2 Newsgroups: sci.space In article Taber@bio2.com writes: > > >Biosphere 2 update 1/12/93 > >Oxygen will be added to Biosphere 2, raising the >concentration to 19%, beginning Wednesday, January 13. > >We allowed the oxygen to drop to its current concentration >of 14.4% primarily to determine if the rate of decline would >reduce with the concentration, and to allow a study to >proceed examining the acclimation of the crew the reduced >partial pressure of oxygen in the atmosphere. Some >aspects of the acclimation appear to possibly have been >delayed for reasons that are not yet clear. Tests done this >week indicated that now all crew members are showing >signs of acclimation. The crew's ability to acclimatize to >falling levels of oxygen indicate the we can function >satisfactorily in the range of 16% to 19% O2. We have >observed no reduction in the rate of oxygen loss since >closure. > >Because of the above results, increased symptoms of >hypoxia being reported from the crew and my concern as >safety officer that a further drop may lead to a safety >problem, we have decided to supplement the oxygen in >Biosphere 2. The oxygen level I am breathing now, as I >key this in, is about equal to the oxygen partial pressure at >an altitude of 13,400 feet, just over 4,000 meters. ... >Taber MacCallum >Biosphere 2 crew member >tmaccallum@igc.org Very interesting! Are the symptoms of non-acclimatized crew members similar to altitude sickness or does the higher total pressure prevent some of the altitude sickness symptoms from appearing? I don't know, but I would assume that HAPE, for instance, requires lower total pressure. Obviously, a crew member with symptoms that severe would require immediate attention, and perhaps evacuation. -- Brad Whitehurst | Aerospace Research Lab rbw3q@Virginia.EDU | We like it hot...and fast. ------------------------------ Date: Wed, 13 Jan 93 21:35:17 EDT From: chico@ccsun.unicamp.br (Francisco da Fonseca Rodrigues) Subject: Planets around nearby sun-like stars Does someone know where can I get information about the formation or the possibility planet formation around the nearby stars? In 1987, after reading for too many years about the Van de Kamp research of Barnard's Star, in which he discovered two planets using astrometry, I read that this was a mistake, and the planets don't exist at all. But in the same year, I read an article from Washington Post, and after that in Astronomy Magazine, about the evidences of planets around the stars Epsilon Eridani and Gamma Cephei. This research was made by Bruce Camp- bell, from The Dominion Astrophysycal Observatory, and the article said he and his team would continue to reaserch others stars, and that they had 5 more candidates, in a total of 16 stars. Does someone know any other information? I am very interested in this subject. I would like to receive information or references about the possibi- lity of existence of planets around : Alpha Centauri, Tau Ceti, Epsilon Erida- ni, 70 Ophiuchi, 82 Eridani, Eta Cassiopeiae, Epsilon Indi, and other stars within 10 parsecs from the sun. To finish, I would like to apologize for my English. Thank you. -----------------------=====================================----the stars,---- | ._, | Francisco da Fonseca Rodrigues | o o | | ,_| |._/\ | | o o | | | |o/^^~-._ | COTUCA-Colegio Tecnico da UNICAMP | o | |/-' BRASIL | ~| | o o o | |\__/|_ /' | Depto de Processamento de Dados | o o o o | | \__ Cps | . | | o o o o | | | * __/' | InterNet : chico@ccsun.unicamp.br | o o o | | > /' | BitNet : cotucamp@brcfetmg | o | | /' /' | Fone/Fax : 55-0192-32-9519 | o o | | ~~^\/' | Campinas - SP - Brasil | o o | -----------------------=====================================----like dust.---- ------------------------------ Date: Wed, 13 Jan 1993 15:42:58 GMT From: kjenks@gothamcity.jsc.nasa.gov Subject: Railgun in Southwest US Newsgroups: sci.space In reply to my posting about railguns and their payloads, in article sch@mitre.org (Stu Schaffner) writes: >You're probably right, but perhaps we just aren't being imaginative enough. >First, couldn't an aluminum or steel ingot survive this g-load without >deforming too badly? I can think of a few peaceful uses for a whole bunch >of these in orbit... Yes, you could theoretically make a useful payload which will survive launch from a railgun. The launch accelleration isn't that much greater than that of a shell fired from an artillery piece, and the military has quite a few interesting things which can be launched that way. However, the accelleration lasts a lot longer, and conventional artillery doesn't deal with the huge electical and magnetic fields, nor does it deal with muzzle velocities in the km/s range. That muzzle velocity gives your payload a double wham -- once during its initial accelleration, and again when it hits the air (railgun chambers are usually evacuated). But making a payload which can survive the launch (like an ingot or something with some SOLID-state electronics) is much different from making a miniature rocket ship which can survive the launch. You'd still need that circularization burn. (See below.) > [...] Second, is there no alternative to a rocket burn for >orbit stabilization? How about giving the ingot a lifting body shape with >a very simple control, like a radio-controlled explosive charge that >deforms a control surface when detonated? A satellite could precisely >determine the ingot's orbit, then deform the control surface at just the >right time during a skip off the atmosphere. Orbital mechanics don't allow you to get into orbit this way. You simply have to get some thrust. Otherwise, you swing back around and fall back into the atmosphere. Aerobraking is good for reducing energy at the lowest point in your orbit, but to circularize an orbit, you need to add energy at the highest point in your orbit. >I highly doubt that what I described would be economical, or even work at >all. Still, it makes me wonder if we should write mass drivers off just >yet. If you could figure out a propulsion system which would survive launch, like maybe a solid rocket motor with pressurized fluid in the core which supports the solid fuel during the periods of extreme accelleration, or maybe a solid-state electric thruster which interacts with the planetary electomagnetic field, and electronics which would survive the incredible electromagnetic fields, it's conceivable to build the payload. But, as you implied, I wouldn't want to pay for the research and test program. Still, the only limitations are engineering concerns. The numbers say rail-gun-launched miniature rocket ships are techncially possible. Maybe one or more branches of the military have actually done it, but they aren't telling. >Stu Schaffner, not speaking for >The MITRE Corp. >(And not involved professionally in this kind of stuff at all) >sch@mitre.org -- Ken "Not professionally involved, either" Jenks, NASA/JSC/GM2, Space Shuttle Program Office kjenks@gothamcity.jsc.nasa.gov (713) 483-4368 "NASA turns dreams into realities and makes science fiction into fact" -- Daniel S. Goldin, NASA Administrator ------------------------------ Date: 13 Jan 1993 18:16:49 GMT From: Chris Johnson Subject: Railgun in Southwest US Newsgroups: sci.space In article <11JAN199312062182@robots> PETER YASUDA, peipyy@robots writes: >It's not a rail gun; it's some kind of gas gun. It's being built >by one of the Energy Dept labs. It uses a really big piston to >compress hydrogen gas which drives the projectile out the launch >tube, which is mounted at a right angle to the piston. Gas is >fed into the launch tube as the projectile passes by. > >The first attempt will be a test with a light projectile. If >successful, the plan is to scale it up. > >Sorry, that's all I recall. I don't even remember where the >article appeared. There's a good article (replete with pictures) in the August 10, 1992 issue of Aviation Week entitled "World's Largest Light Gas Gun Nears Completion at Livermore." In addition, that article refers to another article on the same subject in their July 23, 1990 issue. Evidently, it's a two stage light gas gun, 425 ft. long, built by Lawrence Livermore National Laboratory for $4 million over the last three years. Selected bits of the article follow. Lots of interesting stuff omitted. "When the final pieces are in place late this fall, the Super High Altitude Research Project (SHARP) gun is expected to send a projectile weighing 5 kg. (11 lb.) hurtling into a pile of sandbags at 4 km./sec. (8,945 mph.)." "Soon after SHARP fires its initial test shots into sand bags, Hunter [principal scientist for the SHARP project] plans to move the gun from Livermore to Vandenberg AFB, where it can be fired into the air. The size of the launch tube was set at 4 in. to allow firing a projectile large enough to survive the hypersonic flight through the atmosphere, Hunter said. A smaller projectile would burn up from friction." "[....] Hunter has calculated that the SHARP projectile will reach 450 km. (278 mi.) altitude if launched at 90 deg. and 4 km./sec." Since late fall of '92 is now behind us, the gun should have fired by now. Does anyone know how it went? I haven't noticed any other AW&ST articles on the subject. Other AW&ST articles relevant to current sci.space threads include the really good article on Delta Clipper on p. 55 of the Feb. 3, 1992 issue, and a minor related article on p. 25 of the July 20, 1992 issue. Does anyone out there, by the way, have an on-line index to AW&ST? Finding articles by manually searching through all their contents pages is a bit of a pain. Chris Johnson Internet: chrisj@emx.cc.utexas.edu UUCP: {husc6|uunet}!cs.utexas.edu!ut-emx!chrisj BITNET: chrisj@utxvm.bitnet CompuServe: >INTERNET:chrisj@emx.cc.utexas.edu AppleLink: chrisj@emx.cc.utexas.edu@internet# ------------------------------ Date: Wed, 13 Jan 1993 17:47:22 GMT From: Henry Spencer Subject: russian solar sail?+ Newsgroups: sci.space In article ida@atomic (David Goldschmidt) writes: > This must be solvable. First, there is no reason why all of the blades >have to be attached to the hub at the same level (one could be above another) >This allows you to overlap blades and retain full control over blade angle. If you're going to feather the blades, you can't have blade A's pivot in the arc described by blade B as it changes pitch. This heavily constrains pivot positions in closely-spaced layers. My original comment may have been too pessimistic -- on closer inspection, I think my analysis was oversimplified a bit -- but you have to watch arcs of movement very carefully if you're putting layers closer than one blade width to each other. >Second, even if they were overlapping in the same plane, if you feather all >the blades at once, and in the same direction, they shouldn't interfere with >each other... In this configuration, the feathering works okay, but the *un*feathered position doesn't. The blades can't come to a fully in-plane position (they would hit each other). That means you're going to have a steady torque, spinning up the heliogyro faster and faster. Unless you add some other mechanism for spin control, the blades *have* to be able to reach the in-plane position, and in fact have to be able to tilt slightly in *either* direction from that position, so you can apply torques either way to control spin rate. > ...having 90 degree change ... allows you to precess >the axis of the sail easily. If you get the blades rotating with twice the >period of the heliogyro, so they are all horizantal on one side of the disk >and vertical on the other, this produce a constant torque with no additional >control inputs... If the pitch-change period isn't long compared to the spin period, the dynamics will get complex. I don't have a good feel for the situation, but picture it the other way: get the blades rotating with the heligyro spin stopped, and then try to start the spin -- the blades will try to precess! Unless you make the blades rigid, I don't think you can just rotate them (with the heliogyro spinning) without getting into very complex motions. Note also that if you want the blades rotating, that means 360-degree pitch change, not 90 degrees, which means wider spacings. Even if you counter-rotate adjacent blades, they still have to be at least half a blade width apart. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Wed, 13 Jan 1993 17:18:38 CET From: K3032E0@ALIJKU11.BITNET Subject: SNC meteorites Newsgroups: sci.space,sci.astro,alt.sci.planetary Just a minor update: There are 7 known Shergottites (5 of these were recovered from antarctica, "Shergotty" was seen to fall in India, "Zagami" in Nigeria), giving a total of 11 SNC-meteorites. Herbert ------------------------------ Date: 13 Jan 1993 16:09:20 GMT From: Jon Leech Subject: Weekly reminder for Frequently Asked Questions list Newsgroups: sci.space,sci.astro,sci.space.shuttle This notice will be posted weekly in sci.space, sci.astro, and sci.space.shuttle. The Frequently Asked Questions (FAQ) list for sci.space and sci.astro is posted approximately monthly. It also covers many questions that come up on sci.space.shuttle (for shuttle launch dates, see below). The FAQ is posted with a long expiration date, so a copy may be in your news spool directory (look at old articles in sci.space). If not, here are two ways to get a copy without waiting for the next posting: (1) If your machine is on the Internet, it can be obtained by anonymous FTP from the SPACE archive at ames.arc.nasa.gov (128.102.18.3) in directory pub/SPACE/FAQ. (2) Otherwise, send email to 'archive-server@ames.arc.nasa.gov' containing the single line: help The archive server will return directions on how to use it. To get an index of files in the FAQ directory, send email containing the lines: send space FAQ/Index send space FAQ/faq1 Use these files as a guide to which other files to retrieve to answer your questions. Shuttle launch dates are posted by Ken Hollis periodically in sci.space.shuttle. A copy of his manifest is now available in the Ames archive in pub/SPACE/FAQ/manifest and may be requested from the email archive-server with 'send space FAQ/manifest'. Please get this document instead of posting requests for information on launches and landings. Do not post followups to this article; respond to the author. ------------------------------ Date: 13 Jan 1993 17:14:24 GMT From: Doug Mohney Subject: Who can launch antisats? (was Re: DoD launcher use) Newsgroups: sci.space In article , ewright@convex.com (Edward V. Wright) writes: >In henry@zoo.toronto.edu (Henry Spencer) writes: > >>Define "adequate". Microsat levels of resolution should be adequate >>for many military requirements. Tactical commanders don't care about >>the license-plate numbers on the tanks... > >If you're planning air strikes with smart weapons, 10-meter resolution >isn't going to cut it. You need *which* one of those buildings is the >command bunker. > >Microsats can supplement our current recon satellites, but can't >replace them. Excuse me, but the $1 billion KH-11 should have already pinpointed the (fixed) targets you are frothing about. Nobody is suggesting using microsats as a TOTAL replacement for the expensive stuff; but as a stop-gap fix for information gathering, such as observing the movement of tanks and other hardware. Let's see, a tank-sized object would be oh, ballpark, between 4-5 meters long, 2-3 meters wide, not having a Jane's or other guide at my fingertips. Can you launch a small (What's small Ed? You seem to be the expert today) payload to look down and tell you a group of 4 x 2 meter objects are moving around? It may be a stretch, and I wouldn't expect to tell the difference between a T-62 and a T-80. However, you could look down and see a group of tanks moving from point A to point B, which is the purpose of the exercise of sending up a microsat: Gaining tactical information during a wartime situtation. Assuming you have a KH-11/12/whatever, it would take (Air Force SPACECOM estimate) three MONTHS to launch a replacement. It's been on the neurotic list since the ex-Sovs developed their SS-9 sat killer...oh...late 70s? Bell didn't build a microsat with a telescope in it under contract to DARPA for the entertainment value. And the models and designs are what is public; black projects are not subject to review. I have talked to Ehud, and lived. -- > SYSMGR@CADLAB.ENG.UMD.EDU < -- ------------------------------ End of Space Digest Volume 16 : Issue 044 ------------------------------