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, 11 Mar 90 01:42:35 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 11 Mar 90 01:42:09 -0500 (EST) Subject: SPACE Digest V11 #135 SPACE Digest Volume 11 : Issue 135 Today's Topics: Re: Resolving Power of Hubble Space Telescope Re: Jonathan's Space Report Rides Again... Payload Status for 03/08/90 (Forwarded) Re: Resolving Power of Hubble Space Telescope Re: Phobos Pictures Payload Status for 03/07/90 (Forwarded) Re: Orbital Debris Re: XB-70 and X-15 NASA Headline News for 03/07/90 (Forwarded) ---------------------------------------------------------------------- Date: 10 Mar 90 21:56:46 GMT From: unmvax!nmtsun!nraoaoc@ucbvax.Berkeley.EDU (Daniel Briggs) Subject: Re: Resolving Power of Hubble Space Telescope In article <161@chara.UUCP> don@chara.UUCP (Donald J. Barry) writes: >What was not mentioned is that resolution three times greater is >routinely obtained through ground-based optical speckle interferometry. Correct me if I am wrong, but aren't speckle images often subject to fairly severe image defects? (Not throwing any stones, you understand. It is a _hard_ imaging problem. It can be hard to tell a true feature from an image defect in VLBI too.) I very vaguely remember something about some speckle images of the pluto-charon system that were questioned on the basis that the image of charon fell very close to a maximum in the Fresnel diffraction pattern to be expected from pluto's disk. (I am not even certain that this is the right object. I'd like to be reminded, if anyone remebers the story.) Certainly it is true that imaging a complex source with a limited number of conventional interferometric baselines is a dicey business. In terms of information content, how does speckle interferometry compare with conventional interferomtery? (I.e. that which measures only a single Fourier component of the source per baseline?) All of the speckle images that I have seen have been very simple objects. (Single disk, resolved double point source, and so forth.) This would tend to suggest that information content of a single speckle is not very high. (Perhaps equivalent to a single baseline measurement?) >The "CHARA Array", [...] will have a limiting resolution of 0.2 >milliarcseconds -- a >factor of 100 exceeding any ground-based instrument (and 300 times >better than Hubble!) Well, depends on your wavelength.... I point out that milimeter VLBI experiments are currently running at about 50 microarcseconds on the short axis of the beam ;-) >Of course, these techniques are limited to reasonably bright >sources. You bet. So are ours. >Hubble's principle contribution will be simultaneous solution of several >limits pertaining to ground-based astronomy -- fine resolution of >very dim sources having large dynamic ranges, in visible and UV. ^ [and complicated source structure] >Singly, except for UV spectroscopy, the capabilities of HST have >been duplicated years past by ground based instruments. As I have said before, there are lots of useful techniques and lots of interesting objects crying out to be studied with them. Three cheers for CHARA, HST, and everyone else trying to push the envelope of astronomical observations to new regions of parameter space! ----- This is a shared guest account, please send replies to dbriggs@nrao.edu (Internet) Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801 (U.S. Snail) ------------------------------ Date: Sat, 10 Mar 90 09:38:54 AST From: LANG%UNB.CA@vma.cc.cmu.edu Subject: Re: Jonathan's Space Report Rides Again... On Sat, 10 Mar 90 03:55:22 EST space-request+@andrew.cmu.edu writes: > Orbiting Voice Encoder); and AMSAT-LU's LUSAT. (I don't know what LU > stands for. Anyone who can enlighten me, please do so!) LUSAT is owned by the AMSAT organization in Argentina. All Argentinian amateur radio callsigns begin with the letters LU. ======================================================================== Richard B. Langley BITnet: LANG@UNB.CA or SE@UNB.CA Geodetic Research Laboratory Phone: (506) 453-5142 Dept. of Surveying Engineering Telex: 014-46202 University of New Brunswick FAX: (506) 453-4943 Fredericton, N.B., Canada E3B 5A3 ======================================================================== ------------------------------ Date: 10 Mar 90 18:56:26 GMT From: ames.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 03/08/90 (Forwarded) Daily Status/KSC Payload Management and Operations 03-08-90 - STS-31R HST (at VPF) - HST battery charging and functional testing along with MMSE preps for P/L transfer to the pad were performed yesterday and will continue today. - STS-32R SYNCOM/LDEF (at SAEF-2) LDEF deintegration continues. - STS-35 ASTRO-1/BBXRT (at O&C) - Velcro patch installation and MLI closeout were worked yesterday and will continue today along with canister preps for P/L transfer to the OPF. BBXRT battery box operations and preps for argon servicing will occur today. - STS-40 SLS-1 (at O&C) - The systems test was active yesterday and will continue today. Experiment functional checks will also continue today. - STS-42 IML (at O&C) - Rack 4 staging operations were worked yesterday. Racks 3 and 4 staging operations are scheduled for today. - STS-45 Atlas-1 (at O&C) - Pallet keel installation will be worked today. - STS-46 TSS-1 (at O&C) - PPCU checkout will be active today. ------------------------------ Date: 10 Mar 90 21:23:53 GMT From: cs.utexas.edu!jarvis.csri.toronto.edu!qucdn!gilla@tut.cis.ohio-state.edu (Arnold G. Gill) Subject: Re: Resolving Power of Hubble Space Telescope But isn't the whole point of HST to be able to look 1-2 magnitudes deeper AND have 0.1" resolution. While it may be possible to do one or the other using ground based instruments, the combination itself is important enough to warrant the deployment of HST. ------- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- | Arnold Gill | | | Queen's University at Kingston | If I hadn't wanted it heard, | | BITNET : gilla@qucdn | I wouldn't have said it. | | X-400 : Arnold.Gill@QueensU.CA | | | INTERNET : gilla@qucdn.queensu.ca | | -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ Date: 10 Mar 90 21:27:58 GMT From: frooz!cfa.HARVARD.EDU@husc6.harvard.edu (Bill Wyatt) Subject: Re: Phobos Pictures Check the February 1990 _Sky_&_Telescope_. Bill Wyatt, Smithsonian Astrophysical Observatory (Cambridge, MA, USA) UUCP : {husc6,cmcl2,mit-eddie}!harvard!cfa!wyatt Internet: wyatt@cfa.harvard.edu SPAN: cfa::wyatt BITNET: wyatt@cfa ------------------------------ Date: 10 Mar 90 18:52:28 GMT From: ames.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 03/07/90 (Forwarded) Daily Status/KSC Payload Management and Operations 03-07-90 - STS-31R HST (at VPF) - HST battery charging and functional testing along with MMSE preps for P/L transfer to the pad were performed yesterday and will continue today. - STS-32R SYNCOM/LDEF (at SAEF-2) LDEF deintegration continues. - STS-35 ASTRO-1/BBXRT (at O&C) - Velcro patch installation and MLI closeout were worked yesterday and will continue today along with canister preps for P/L transfer to the OPF. - STS-40 SLS-1 (at O&C) - The systems test was active yesterday and will continue today. Experiment functional checks will also continue today. - STS-42 IML (at O&C) - Rack 8 staging operations were worked yesterday. Racks 4 and 11 staging operations are scheduled for today. - STS-45 Atlas-1 (at O&C) - Orthogrid hardpoint installations were worked yesterday and will continue today. - STS-46 TSS-1 (at O&C) - PPCU checkout will be active today. ------------------------------ Date: 11 Mar 90 00:01:55 GMT From: swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Orbital Debris In article <2747@castle.ed.ac.uk> aipp@castle.ed.ac.uk (Pavlos Papageorgiou) writes: > Is there an agreement or organisation regulating this? A centre >for tracking the orbits? What about unreported launces (e.g. foreign >intelligence)? There are international agreements regarding assignment of comsat slots in Clarke orbit. Otherwise, not much. There is an international agreement to announce launches, basically so nobody gets too excited about an unexpected rocket launch, but no central coordination of orbits and such. NASA checks each shuttle orbit against everything in NORAD's tracking catalog, but otherwise satellites just take their chances. So far, there is no known case of serious damage, although micro-cratering of external surfaces is becoming a disturbing problem. > Do smaller objects 'spiral down' faster? Generally, yes, because the square-cube law gives them greater surface area per kilogram and hence they are more affected by air drag. There are an awful lot of them up there, unfortunately. >How much damage would a >minor impact cause the space station and how (un)likely is it? It depends on what you mean by "minor". The station will be armored against small impacts; this is routine for large pressurized spacecraft. Hitting something the size of your fist would be pretty nasty, though. >Would >practices like explosive bolts and discared booster stages have to be >reviewed? It is already normal, in Western countries, to use explosive separation hardware that does not spray debris around when it fires. In general, the launcher folks have cleaned up their act greatly in recent years. Spent stages still do get left in orbit, but at least precautions are now taken to make sure they don't explode due to residual propellants. (Delta second stages used to be notorious for this, and were a major contributor to the debris problem.) >What about things like nuclear power cells re-entering the atmosphere? This isn't a *big* problem except when the Soviets have a radarsat get away from them. Use of nuclear power in Earth orbit is actually fairly rare at present. Nobody but the USSR has space-qualified reactors, and apart from a couple of test launches for the Topaz reactor, they use them only on the radarsats. (Both the Topazes and the radarsats were quite noticeable to the radiation detectors on Solar Max, by the way.) Even having a small reactor burn up in the atmosphere is not that big a deal; it's no worse than one or two French or Chinese nuclear tests. Isotope generators in orbit are no problem, since they too are rare and they are designed to survive reentry intact. -- MSDOS, abbrev: Maybe SomeDay | Henry Spencer at U of Toronto Zoology an Operating System. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 10 Mar 90 14:46:14 GMT From: skipper!shafer@ames.arc.nasa.gov (Mary Shafer (OFV)) Subject: Re: XB-70 and X-15 In article <1990Mar9.092642.13013@axion.bt.co.uk> apengell@axion.bt.co.uk (alan pengelly) writes: Incidently, does anyone know what characteristics of the X-15 were inherited by the Shuttle, i.e. lift/drag ratio etc? Strikes me that the X-15 was a superb research programme and that its value is somewhat understated. Offhand, I'd say the reaction control system and heating problems. Most of the influence on the Shuttle came from the lifting bodies. They weren't as flashy as the X-15, and are not nearly so well known. But the Shuttle is just a _big_ lifting body with a wing. -- Mary Shafer shafer@skipper.dfrf.nasa.gov or ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA ------------------------------ Date: 10 Mar 90 18:37:52 GMT From: ames.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 03/07/90 (Forwarded) ----------------------------------------------------------------- Wednesday, March 7, 1990 Audio: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Wednesday, March 7...... The Atlantis ferry flight from the Dryden Flight Research Facility to the Kennedy Space Center remains scheduled for Saturday. Access to the orbiter main engine compartment revealed a two gallon hydraulic system leak from a one-inch split in an outlet hose in auxiliary power unit one. Officials are determining whether the line needs to be replaced. Hypergolic servicing begins tomorrow. Meanwhile, at the Kennedy Space Center Vehicle Assembly Building, Discovery has been lifted off the orbiter transporter and rotated to a vertical position. There it was mated to the external tank and solid rocket boosters. A shuttle interface test starts tomorrow to verify electrical and mechanical connections between launch vehicle elements. Rollout to Pad 39-B is scheduled for 8:00 A.M. Thursday, March 15. Power for the Hubble Space Telescope is on today and tomorrow as closeout operations continue at KSC. A new cocoon has now been placed over the spacecraft. Installation into the payload canister is scheduled for March 23 with the move to the launch pad on March 26. The launch is targeted for April 12. Langley Research Center technicians at KSC to date have removed 27 experiment trays from the Long Duration Exposure Facility. Twelve million tomato seeds are being packaged in kits to be sent to educators around the country this week. If planted within the next few weeks, they should bear fruit by June 1. Some test seeds removed from the first two canisters for the student experiment have already germinated. The first Pegasus air-launch booster for Orbital Sciences Corporation has been postponed by the Defense Advanced Research Projects Agency to early April. This will allow for an independent study of critical engineering analyses and operational procedures. #### ----------------------------------------------------------------- Here's the broadcast schedule for public affairs events on NASA Select TV. All times are Eastern. Thursday, March 8..... 11:30 A.M. NASA Update will be transmitted. Thursday, March 15...... From Goddard Space Flight Center 9:00 A.M. Hubble Space Telescope science briefing. 12:00 P.M. Preparation, deploy and verification servicing briefing. 5:00 P.M. How to cover the mission. Monday, March 19...... From Johnson Space Center 9:30 A.M. STS-31 flight directors mission overview. 10:30 A.M. Secondary mid-deck student experiments. 11:30 A.M. Flight crew news conference. Wednesday, March 21... 1-2:30 P.M. Total Quality Management in Action colloquium. 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. ------------------------------ End of SPACE Digest V11 #135 *******************