skippy@jhunix (Ian Chesterton) (10/31/89)
Just a quickie. After reading so much about the LDEF's predicament, I'd like to know if NASA's will do anything about getting it before it does a SKYLAB. Is it possible for the shuttle to fly a dual mission? For example launch a satellite and retrieve the LDEF. --- Ian ---
henry@utzoo.uucp (Henry Spencer) (11/01/89)
In article <3115@jhunix.HCF.JHU.EDU> skippy@jhunix (Ian Chesterton) writes: >Just a quickie. After reading so much about the LDEF's predicament, I'd like >to know if NASA's will do anything about getting it before it does a >SKYLAB. They're going to try, with the December shuttle launch. >Is it possible for the shuttle to fly a dual mission? For example >launch a satellite and retrieve the LDEF. This is exactly what's going to happen in December. Dual missions are not at all uncommon; for example, LDEF was launched by the same mission that repaired Solar Max. (I saw it go up. Quite different from watching on TV, even from the cheap seats far away from the pad.) Mind you, this particular mission should have been flown earlier. Blame politics and the glacially-slow Challenger recovery. As it is, it's going to be close for LDEF. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
smb@ulysses.homer.nj.att.com (Steven M. Bellovin) (11/01/89)
In article <3115@jhunix.HCF.JHU.EDU>, skippy@jhunix (Ian Chesterton) writes: > Just a quickie. After reading so much about the LDEF's predicament, I'd like > to know if NASA's will do anything about getting it before it does a > SKYLAB. Is it possible for the shuttle to fly a dual mission? For example > launch a satellite and retrieve the LDEF. I belive that that is exactly what is planned, on the December mission. DoD is launching a spooksat mission of some flavor in November.
petej@phred.UUCP (Pete Jarvis) (11/02/89)
In article <3115@jhunix.HCF.JHU.EDU> skippy@jhunix (Ian Chesterton) writes: >Just a quickie. After reading so much about the LDEF's predicament, I'd like >to know if NASA's will do anything about getting it before it does a NASA is going to use Columbia in December to retrieve LDEF. Otherwise in would re-enter the atmoshere in Jan. or Feb. and burn up. Peter Jarvis....
steve@nuchat.UUCP (Steve Nuchia) (11/04/89)
In article <2831@phred.UUCP> petej@phred.UUCP (Pete Jarvis) writes: >NASA is going to use Columbia in December to retrieve LDEF. Otherwise >in would re-enter the atmoshere in Jan. or Feb. and burn up. Gee, why does this remind me of all the projects I ever waited until the last minute to get started on? I don't think a smiley is called for. Sigh. -- Steve Nuchia South Coast Computing Services uunet!nuchat!steve POB 270249 Houston, Texas 77277 (713) 964 2462 Consultation & Systems, Support for PD Software.
bobal@microsoft.UUCP (Bob Allison) (11/07/89)
In article <1989Nov1.024354.6148@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > > [...] >This is exactly what's going to happen in December. Dual missions are >not at all uncommon; for example, LDEF was launched by the same mission >that repaired Solar Max. (I saw it go up. Quite different from watching >on TV, even from the cheap seats far away from the pad.) > >Mind you, this particular mission should have been flown earlier. Blame >politics and the glacially-slow Challenger recovery. As it is, it's going >to be close for LDEF. And we're losing Solar Max for sure. Coming down in November-December I hear. NASA thinks chunks ranging in size from 75 to 300 pounds could reach the surface. Only a small land area is involved, though, and NASA estimates chances of a human being hit as 1 in 3800 (which sure seems high to me). That's one defect with designing a satellite which must be serviced by the shuttle at regular intervals (much less if we ever had a dozen up at once; so far the plans only include HST and the space station as far as I know). Bob Allison uunet!microsoft!bobal
tneff@bfmny0.UU.NET (Tom Neff) (11/07/89)
Bob Allison reminds us Solar Max will soon join Skylab and says: >That's one defect with designing a satellite which must be serviced by the >shuttle at regular intervals (much less if we ever had a dozen up at once; >so far the plans only include HST and the space station as far as I know). There is a useful distinction between building a satellite that must be SERVICED by the shuttle (boards replaced, film collected, whatever) and one that must actually be REBOOSTED by it. The former is merely questionable, the latter is downright dangerous. It ought to be an international agreement that anything large enough to be dangerous on re-entry must orbit high enough to stay up for decades. LDEF, Max, Skylab, and all that Soviet iron are Damoclean hazards. Not to mention damn expensive to lose at a year's slippage. -- There's nothing wrong with Southern California that a || Tom Neff rise in the ocean level wouldn't cure. -- Ross MacDonald || tneff@bfmn0.UU.NET
henry@hutto.UUCP (Henry Melton) (11/07/89)
I have been attempting to keep an 'eye' on LDEF using the sat data posted by T. Kelso and using a couple of tracking programs; MACSAT and a ported version of SEESAT. The MACSAT program shows it at 381 km and not dropping at all over the next couple of months. SEESAT has it slightly lower and dropping about a half a km per day. Does anyone out there have any better information? I assume the decay rate will increase -- but how fast? And at what altitude will the tumbling begin, (if we don't catch it first)? -- Henry Melton ...!cs.utexas.edu!ut-emx!hutto!henry 1-512-8463241 Rt.1 Box 274E Hutto,TX 78634
bobal@microsoft.UUCP (Bob Allison) (11/10/89)
In article <14861@bfmny0.UU.NET> tneff@bfmny0.UU.NET (Tom Neff) writes: >Bob Allison reminds us Solar Max will soon join Skylab and says: >>That's one defect with designing a satellite which must be serviced by the >>shuttle at regular intervals (much less if we ever had a dozen up at once; >>so far the plans only include HST and the space station as far as I know). > >There is a useful distinction between building a satellite that must be >SERVICED by the shuttle (boards replaced, film collected, whatever) and >one that must actually be REBOOSTED by it. The former is merely >questionable, the latter is downright dangerous. > Well, I did say "must be serviced by the shuttle at regular intervals", not "can be serviced if necessary". If it can be reached by the shuttle and "must be serviced", then that service is going to include fuel. Anyway, what is the estimated time between "fill-ups" for HST? Hopefully, it is longer than the interval between the launch before Challenger and the launch afterwards (which is the only data point we've got for shuttles, although presumably next time the delay will be less). And I do mean "when" and not "if". In regards to how fast LDEF is deteriorating, I don't know, but the article said Solar Max was dropping a mile a day. That article in SciAm about Space Shuttle glow was pretty interesting: yet another reason we don't want to be in quite-that-low-earth-orbit. Looks like they've incorporated some changes into HST for it, though. Bob Allison uunet!microsoft!bobal
thomas@mvac23.UUCP (Thomas Lapp) (11/10/89)
tneff@bfmny0.UU.NET (Tom Neff) writes: > > It ought to be an international agreement that anything large enough to > be dangerous on re-entry must orbit high enough to stay up for decades. > LDEF, Max, Skylab, and all that Soviet iron are Damoclean hazards. Not > to mention damn expensive to lose at a year's slippage. > -- Why should things which could hit earth on re-entry be required to stay up for decades? It just means that our generation doesn't have to worry about it, but a future earth (with a denser population -- more chance of it hitting someone). - tom -- internet : mvac23!thomas@udel.edu or thomas%mvac23@udel.edu uucp : {ucbvax,mcvax,psuvax1,uunet}!udel!mvac23!thomas Europe Bitnet: THOMAS1@GRATHUN1 Location: Newark, DE, USA Quote : Virtual Address eXtension. Is that like a 9-digit zip code? -- The UUCP Mailer
tneff@bfmny0.UU.NET (Tom Neff) (11/10/89)
In article <8739@microsoft.UUCP> bobal@microsoft.UUCP (Bob Allison) writes: >That article in SciAm about Space Shuttle glow was pretty interesting: yet >another reason we don't want to be in quite-that-low-earth-orbit. Wasn't it though! I was going to post about it but procrastinated. The gist: LEO is definitely *in* the atmosphere -- a billion atoms per cubic centimeter, much of it monatomic oxygen which proves HIGHLY reactive on all sorts of surfaces. Kapton film, used for many structural purposes because of its strength and lightness, erodes at several mm/yr. The films supporting the Space Station solar array, as currently planned, might be gone in a year! Coatings disappear, clear plastic turns opaque, and the black-painted shuttle tail *glows* visibly yellow at night when it's facing the wind. > Looks >like they've incorporated some changes into HST for it, though. The paint that glows so brightly will no longer line the optical tube :-) Let's hope we know enough about what else can happen. I wonder if the cradle they're building for LDEF will work if it's HALF AN INCH SMALLER in diameter as is possible extrapolating some of the SciAm numbers... -- When I was [in Canada] I found their jokes like their | Tom Neff roads -- not very long and not very good, leading to a | tneff@bfmny0.UU.NET little tin point of a spire which has been remorselessly obvious for miles without seeming to get any nearer. -- Samuel Butler.
tneff@bfmny0.UU.NET (Tom Neff) (11/10/89)
In article <104.UUL1.3#5131@mvac23.UUCP> thomas@mvac23.UUCP (Thomas Lapp) writes: >Why should things which could hit earth on re-entry be required to stay >up for decades? It just means that our generation doesn't have to worry >about it, but a future earth (with a denser population -- more chance of >it hitting someone). It improves the odds on a reboost. And if they don't, hey -- what has the future earth ever done for US? :-) -- When I was [in Canada] I found their jokes like their | Tom Neff roads -- not very long and not very good, leading to a | tneff@bfmny0.UU.NET little tin point of a spire which has been remorselessly obvious for miles without seeming to get any nearer. -- Samuel Butler.