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 ; Thu, 1 Mar 90 02:48:25 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 1 Mar 90 02:47:59 -0500 (EST) Subject: SPACE Digest V11 #94 SPACE Digest Volume 11 : Issue 94 Today's Topics: Re: HST damage in orbit Re: Fun Space Fact #1: Launcher Development Costs FYI: NSS Phone Tree Activation Re: Fun Space Fact #1: Launcher Development Costs SPACE ---------------------------------------------------------------------- Date: 27 Feb 90 19:41:39 GMT From: frooz!cfa.HARVARD.EDU@husc6.harvard.edu (Steve Willner, OIR) Subject: Re: HST damage in orbit From article <1990Feb18.062317.3937@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): [For HST damage by atomic oxygen:] > and I believe observation planning now includes a constraint reading > roughly "do not point forward along the orbital velocity vector for any > length of time" to protect the optics. If so, that is quite a serious constraint for any object that lies nearly in the direction of the orbit plane. HST takes a good fraction of an orbit to slew through much of an angle, and many observations want more than an orbit of exposure time anyway (with the shutter closed while pointing at the Earth). Thus there is presumably a section of sky that cannot be observed. No doubt the orbit plane precesses, so any object will eventually come to lie in a "good" direction. Anybody know what the precession period is? SIRTF had a similar constraint back when it was supposed to be in LEO. The worry was that residual atmospheric gases would stick to the cryogenic mirror. However, the slew time already had to be fast to satisfy the other pointing constraints, so the main effect was to halve the maximum time on an individual target. ------------------------------------------------------------------------- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA Internet: willner@cfa.harvard.edu ------------------------------ Date: 28 Feb 90 01:51:09 GMT From: thorin!cezanne!leech@mcnc.org (Jonathan Leech) Subject: Re: Fun Space Fact #1: Launcher Development Costs In article <9002261820.AA26142@aristotle.jpl.nasa.gov> pjs@aristotle-gw.jpl.nasa.gov (Peter Scott) writes: >Well, Kutyna may have known as well, but in a talk which I attended at >Caltech (which was later worked into an article, "Mr. Feynman Goes to >Washington"), Feynman said that the day after he decided to join the >commission, he went to JPL for an intensive meeting, and almost the first >thing in the notes he took was the suggestion that the accident was due >to O-ring failure in the SRB. That page of his notes was reproduced in >the article, wish I could remember where the darn thing was published. Caltech Engineering & Science Magazine, and Physics Today (a somewhat enhanced version, I think). No, I don't have cover dates. -- Jon Leech (leech@cs.unc.edu) __@/ Brice: "How many people don't know anything about it?" Andy: "About what?" ------------------------------ Date: 27 Feb 90 20:01:34 GMT From: ox.com!itivax!vax3!aws@CS.YALE.EDU (Allen W. Sherzer) Subject: FYI: NSS Phone Tree Activation OFFICIAL NSS PHONE TREE ALERT! (Jim Plaxco, Midwest Phone Tree coordinator called me (Tihamer Toth-Fejel) Sunday night, Feb 25, 1990. The House Budget Subcommitte Deadline: March 6th call or write your congressperson if he or she is on the Budget Comittee (see list below for name, district, and phone). Indicate that you want full funding for Function 250 in the Budget Committee. (function 250 includes NASA, NSF, and some areas of DOE) I'm going to add that its in investment in our future, etc. All phone numbers are in area code 202 Democrats: Beilenson (CA) 23rd district Beverley Hills 225-5911 Berman (CA) 26th district, Van Nuys 225-4695 Boxer (CA) 6th district, Barton County 225-5161 Bryant (TX) 5th district, Dallas 225-2231 Durbin (IL) 20th district, Springfield 225-5271 Dwyer (NJ) 6th district, Edison 225-6301 Espy (MS) 2nd district, Vicksburg 225-5876 Guarini (NJ) 14th district, Jersey City 225-2765 Huckaby (LA) 5th district, Monroe 225-2376 Jenkins (GA) 9th district, Dalton 225-5211 Kaptur (OH) 9th district, Toledo 225-4146 Kildee (MI) 7th district, Flint 225-3611 Leath (TX) 11th district, Waco 225-6105 Oberstar (MN) 8th district, Duluth 225-6211 Panetta (CA) Chairman 16th district Monterey 225-2861 Russo (IL) 3rd district, Oak Lawn 225-5736 Sabo (MN) 5th district, Minneapolis 225-4755 Schumer (NY) 10th district, Flatbush 225-6616 Slattery (KS) 2nd district, Topeka 225-6601 Wise (WV) 3rd district, Charleston 225-2711 Republicans: Armey (TX) 26th district, Arlington 225-7772 Bentley (MD) 2nd district, Towson 225-3061 Buechner (MO) 2nd district, Kirkwood 225-2561 Frenzel (MN) (ranking Republican) 3rd district, Bloomington 225-2871 Gallo (NJ) 11th district, Parsippani 225-5035 Goodling (PA) 19th district, York 225-5836 Gradison (OH) 2nd district, Cincinnati 225-3164 Houghton (NY) 34th district, Corning 225-3161 Kasich (OH) 12th district, Columbus 225-5355 McCrery (LA) 4th district, Shereveport 225-2777 Rogers (KY) 5th district, Somerset 225-4601 Schuette (MI) 10th district, Midland 225-3561 Smith (OR) 2nd district, Medford 225-6730 Thomas (CA) 20th diistrict Bakersfield 225-2915 ---------------------------------------------------------------------------- | Allen W. Sherzer | God is real unless declared integer | | aws@iti.org | | ---------------------------------------------------------------------------- ------------------------------ Date: 26 Feb 90 23:59:34 GMT From: mnetor!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: Fun Space Fact #1: Launcher Development Costs In article <25101@ut-emx.UUCP> bonin@ut-emx.UUCP (Marc C. Bonin) writes: >> I must have missed something here -- why does being bigger automatically >> imply operating with smaller safety margins, nearer the limits of the >> parts? ... > >The mass of an object scales as the cube of the dimensions. Consequently, >acceleration forces will also scale cubically. The cross sectional areas of >the vehicle's various components will increase as the square of the dimensions. >Therefore stress (load/area) will scale linearly with size. And therefore the parts of a 747 are circa 100 times more stressed than the ones in a Cessna, and thus -- since the Cessna does not have safety factors of 100! -- 747s cannot fly? Sorry, this is not the explanation I was after. I know about the square-cube law, but the existence of both Cessnas and 747s demonstrates that this is a manageable problem for many purposes. I'm not suggesting you can scale things up with an enlarger; clearly you have to redesign, not just enlarge all the dimensions, when going from a Cessna to a 747. But I don't think the 747's safety margins are much smaller than those of a Cessna; if anything, it has to meet rather tougher standards. -- "The N in NFS stands for Not, | Henry Spencer at U of Toronto Zoology or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Thu, 01 Mar 90 08:41:32 SET From: ESC1413%ESOC.BITNET@vma.cc.cmu.edu Comment: CROSSNET mail via MAILER@CMUCCVMA Subject: SPACE Date: 01 March 1990, 08:36:02 SET From: Stuart Symonds ESC1413 at ESOC To: SPACE at ANDREW.CMU.EDU PLEASE REMOVE MY USER ID FROM THE SPACE DISTRIBUTION LIST. I HAVE TRIED SENDING A NOTE TO SPACE-REQUEST MANY TIMES BUT HAV'NT HAD ANY LUCK SO I THOUGHT I'D TRY THIS ONE 8-). ------------------------------ End of SPACE Digest V11 #94 *******************