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 ; Sat, 3 Mar 90 02:13:24 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 3 Mar 90 02:12:58 -0500 (EST) Subject: SPACE Digest V11 #105 SPACE Digest Volume 11 : Issue 105 Today's Topics: Thiokol wasn't punished (was Re: Fun Space Fact #1) Re: Pegasus Update - 03/01/90 Galileo Update - 02/28/90 Re: Pegasus Update - 03/01/90 Re: Challenger Last Words Re: Dissassembling the Sun Voyager Update - 03/02/90 Re: LDEF - Protection from atmosphere? Re: Ariane V36: Mission lost Re: SPACE Digest V11 #80 ---------------------------------------------------------------------- Date: Wed, 28 Feb 90 17:08:01 CST From: lfa@vielle.cray.com (Lou Adornato) Subject: Thiokol wasn't punished (was Re: Fun Space Fact #1) attcan!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) writes: >Very true, alas. Likewise a system that rewards people for their complicity >in the disaster. What, you thought Morton Thiokol was *penalized* for what >they did? Ho ho, not so. They got umpty-million dollars to fix the SRB >problems, and the notion of an alternate source for SRBs was shelved for >years. Isn't that a *wonderful* example for the next time some engineer >tries to convince his management that they should do the right thing? I can understand this, even if it seems at first to be counter-intuitive. Thiokol had more experience than anyone else with the SRB's, and it just wouldn't make sense to add some other company's learning curve time to the inevitable program suspension. As for shelving the secon source SRB supplier, this was probably necessary to convince Thiokol that it would have to live with the new design (I've seen the difference between a design done by the same company that expected to do the fabrication, and one done by an outside agency). Also, the cost of bringing a second source on line is pretty high, and NASA had to buy a whole new orbiter. There's also the matter of whether Thiokol could have remained solvent through the redesign effort if NASA hadn't made a commitment (Thiokol stock was probably pretty low at the time). There's also the fact that Thiokol wasn't really responsible for the accident, except maybe in that the field joint wouldn't have had to exist if Thiokol was based in central Florida (the SRB's are jointed so that they can be shipped by rail). The accounts that I've read (nope, didn't get a copy of the Rogers report - anyone know where I can get one?) say that everyone involved knew that there was a problem with the design of the joint. There was a _lot_ of evidence that the primary seal was useless (it died in something like 80% of the time, leaving the backup seal as the only protection). It doesn't take a whole lot of statistical reliability to know that if you're counting on your backup system most of the time, you have _NO_ true backup capability. The bottom line is that the NASA managers in Huntsville let the launch become the primary objective, and forgot thier real job was a safe launch; they should never have put the Thiokol engineers in the position of having to prove that the mission was unsafe. Personally, I don't feel that this is so much an indictment of NASA as a statement on the behavior of organizations under pressure. As to the castigation of Boisjoly, I think it sucks. The man blew the whistle before _and_ after the fact. Saying that he deserves to be pillloried because he let himself be browbeaten by NASA and his employer is nonsense. I also think that it sucks that some people (technophobes) act like NASA reliability figures are never to be trusted again, and point to NASA's own "consrevatization" of previously stated figures as proof of this theory. I was a kid in a NASA/Contractor neighbohood at the time of the Apollo 1 fire, and it felt like everyone I knew had lost 3 family members. You can bet the house that any NASA manager or engineer would pass a brick before he/she would let another questionable launch happen. Lou Adornato | Statements herein do not represent the opinions or attitudes Cray Research | of Cray Research, Inc. or its subsidiaries. lfa@cray.com | (...yet) ------------------------------ Date: 2 Mar 90 03:20:11 GMT From: rochester!yamauchi@pt.cs.cmu.edu (Brian Yamauchi) Subject: Re: Pegasus Update - 03/01/90 In article <2961@jato.Jpl.Nasa.Gov> baalke@mars.jpl.nasa.gov (Ron Baalke) writes: [quoting a NASA press release, I believe] > Launch of the Pegasus satellite (Pegsat) has been >rescheduled for April 4, according to Project Manager Bob Pincus. >Pegsat will be launched from a NASA B-52 over the Pacific Ocean >about 50 miles west of Vandenberg Air Force Base, CA. Is this Pegsat the same as the OSC/Hercules Pegasus launcher? And if so, does it make sense to call it a satellite? _______________________________________________________________________________ Brian Yamauchi University of Rochester yamauchi@cs.rochester.edu Computer Science Department _______________________________________________________________________________ ------------------------------ Date: 1 Mar 90 23:48:55 GMT From: elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@lll-winken.llnl.gov (Ron Baalke) Subject: Galileo Update - 02/28/90 GALILEO MISSION STATUS February 28,1990 The Galileo spacecraft is 48.4 million miles from Earth today; this distance is still increasing, and will for the next three months, even though the trajectory leads toward an encounter with Earth in December. Round-trip light time is 8 minutes 41 seconds. The spacecraft passed through perihelion (closest to the Sun) February 25. Galileo has now gone 226 million of the 2.4 billion miles along its looping 6-year path to Jupiter. Health of the spacecraft remains excellent; it is in dual spin, performing some cruise science data collection and engineering maintenance functions such as sun-pointing maneuvers. The telemetry rate is 40 bits per second; about March 6 this will go to 10 bits per second consistent with communications link capability. Galileo's activities are controlled by an onboard-stored program or flight sequence activated February 19 and due to run through March 26. Galileo is now committed to encountering the Gaspra asteroid. The propellant margin estimate is at a negative 17.6 pounds with a 90% confidence. Galileo's thrusters are about 2% more efficient than expected. The decision to proceed to the Ida asteroid won't be made until after the Gaspra encounter. Galileo's two ultraviolet spectrometers have shown that hydrogen atoms at Earth's distance from the sun last about 1 million seconds (almost 12 days) before ionizing. Also, Galileo is already reporting on the ultraviolet spectra of the star Kappa Velorum and on impacts by space dust. The largest piece yet detected weighed about one hundred-millionth of a gram and measured about 26 microns across. The next sequence, to run through April 23, is being processed and reviewed by the flight team. Like the current one, the next sequence will include spacecraft maintenance activities and some cruise science observations; it also includes the first portion of the trajectory correction maneuver to help shape the flight path for December's Earth gravity-assist flyby, next step in propelling Galileo to Jupiter. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: 2 Mar 90 16:47:03 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Pegasus Update - 03/01/90 In article <1990Mar2.032011.29401@cs.rochester.edu> yamauchi@cs.rochester.edu (Brian Yamauchi) writes: >Is this Pegsat the same as the OSC/Hercules Pegasus launcher? And if >so, does it make sense to call it a satellite? Pegsat is the *payload* for the first Pegasus launch. -- MSDOS, abbrev: Maybe SomeDay | Henry Spencer at U of Toronto Zoology an Operating System. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 28 Feb 90 16:58:42 GMT From: snorkelwacker!usc!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo!henry@bloom-beacon.mit.edu (Henry Spencer) Subject: Re: Challenger Last Words In article <23146@usc.edu> robiner@iris.usc.edu (Steve Robiner) writes: >Does anyone out there know if the last minutes of the Challenger >flight recorder were ever released... Yes. It's not interesting. Apart from some bits of irrelevant chatter early on, the only thing that's on the recorder tape that didn't get out on the radio was Smith (probably) saying "uh-oh" just as the accident started. Shuttle orbiters do not carry armored flight recorders; this was just an ordinary tape recorder in the cabin, and it stopped when the orbiter broke up and power was lost. The only decisive evidence that the crew survived the breakup -- apart from the fact that it wasn't violent enough to kill them -- is that some of the emergency air packs in the cabin had been activated, which is a manual operation, and is unlikely to be duplicated by flying debris. (Unfortunately, the packs were meant for ground emergencies, and contained air rather than oxygen, so they weren't much help at 80,000ft.) -- "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: 1 Mar 90 23:07:59 GMT From: frooz!cfa.HARVARD.EDU@husc6.harvard.edu (Steve Willner, OIR) Subject: Re: Dissassembling the Sun From article <1990Feb18.032915.4123@cs.rochester.edu>, by dietz@cs.rochester.edu (Paul Dietz): [Future advanced civilizations may] >> disassemble the outer planets and then the sun (the latter is >> the hardest; you need on the order of 10^7 years if you fully utilize >> the sun's power output; presumably more power could be produced to >> speed things up). In article <325@cfa.HARVARD.EDU>, I replied: > Longer than that, I suspect. If the Sun were of uniform density, its > potential energy would be just 1.2 G M^2/R (if I've done the integral > right). Nope, I goofed. Paul correctly points out that the numerical factor in front should be 0.6 (for the uniform density case). What happens for the real Sun, which is denser at the center? Clearly the factor out front should be larger, but how much? Paul writes: >> I deliberately ignored the nonuniform density of the sun. >> However, the radius goes as density ^ {-1/3}, so even if the >> sun were a sphere with a uniform density equal to the density at the >> center (150 grams/cc vs. the mean density of 1.41 grams/cc) the >> binding energy would be only 4.7 times larger. i.e., the factor out front cannot be larger than 2.8. After some browsing around, it seems that for the simplest stellar models (ideal gas law, uniform chemical composition, hydrostatic equilibrium), the factor in front would be 1.5. The factor for the Sun will be slightly larger, since helium is concentrated toward the center. An old reference (that just happens to be handy) gives 2.0, but also gives a central density of 100, not 150. Thus it's in fact not a bad approximation (for computing the potential energy) to say that the bulk of the mass of the Sun is at a uniform density equal to the central value. (Stellar structure pundits are invited to provide better answers but should probably omit sci.space.) Another correction that neither one of us considered is the internal thermal energy of the Sun. The energy needed to dissipate the Sun to infinity is the gravitational binding energy _minus_ the thermal energy. But according to the virial theorem, the thermal energy is exactly half the gravitational binding energy. > The time for the Sun to radiate that amount of energy at its > current luminosity would be 4E7 years [or larger] After the above corrections, it's something like 3E7 years. Less if you can get the nuclear energy out faster, (e.g. supernova) longer if your process efficiency is less than one (don't want to generate lots of neutrinos, unless you can afford to waste energy). Incidentally, this same calculation shows that the Solar energy source cannot be gravitational if you think that the Sun has been shining (at nearly its current luminosity) longer than 3E7 years. References: Allen 1963, _Astrophysical Quantities_, p. 161ff. Cox and Giuli 1968, _Principles of Stellar Structure, vol. 2_, p. 703ff. ------------------------------------------------------------------------- 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: 3 Mar 90 03:24:38 GMT From: zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!jarthur!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov!baalke@tut.cis.ohio-state.edu (Ron Baalke) Subject: Voyager Update - 03/02/90 Voyager Mission Status Report March 2, 1990 Voyager 1 Voyager 1 continues to collect routine cruise science data. On February 17, the Magnetometer measured an increase in the magnetic field by a factor of 2 or more. The Plasma, CRS, and LECP instruments are not recording any corresponding change. On February 19, an ultraviolet spectrum (UVS) observation was executed from the source SV Centauri (aka HD 102552). Only the first one and one-half hours of the five hour data mode period was received due to the lack of Deep Space Network (DSN) 70-meter support. On February 21, the Attitude and Articulation Control Subsystem (AACS) A and B gyros were reinitialized. Photopolarimter Radiometer (PRA) data is processed and analyzed data daily for the purpose of observing and logging radio events of interest to the PRA team. Voyager 2 AACS Scan Platform Slews on February 19 and February 22 were executed without downlink visibility due to lack of DSN support. A UVS observation was executed on February 21. UVS low-rate data were taken on sources Feige 7 and EG165, a white dwarf. High-rate data were taken on EG165 on February 21. Only three and one-half hours of the twelve hour data mode was observed due to lack of sufficient DSN support. Spacecraft performance for all the sequenced activity during this report period has been nominal. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: Fri, 2 Mar 90 12:26:19 CST From: Will Martin To: sw%groucho.att.com@UUNET.UU.NET Cc: space@ANDREW.CMU.EDU Subject: Re: LDEF - Protection from atmosphere? >Why should the atmosphere affect the radiation and erosion damage? Well, I was thinking that the panels and pieces would be in a sort of "raw" state when retrieved, with the surfaces modified by the years of exposure. As soon as oxygen got to those sufaces, they would begin to oxidize. The material on the surface would not be the same as it was in space. Also, atmospheric pollutants could attack them, destroying or at least modifying the state they were in after years of exposure to vacuum (at least what level of vacuum is in LEO) and various space-borne stuff like free ions. I wouldn't be surprised if various materials migrated because of the vacuum, or if alloys tended to separate. There might be a sort of few-atoms-thick layer of unusual material or pure elements on the surface. Exposure to air might destroy that thin layer or modify it into unrecognizability. I'm not saying all the information would be lost, but some must be. It is like retrieving sunken artifacts -- when exposed to air they crumble. Or the difference between a slightly-weathered rock face and a freshly-cleaved-off chunk of mineral sample. There always is *some* effect of the air. Will ------------------------------ Date: 1 Mar 90 16:59:41 GMT From: van-bc!ubc-cs!kiwi!dssmv2!fischer@ucbvax.Berkeley.EDU (Roger Fischer) Subject: Re: Ariane V36: Mission lost In article <1065@esatst.yc.estec.nl> neil@esatst.UUCP (Neil Dixon) writes: >... >At H0+101 s, the high dynamic pressure attained created excessive >stresses on the structure and triggered the explosion of the launcher >at an altitude of about 9 km and 12.5 km away from the launch pad. >... Do I understand this right? The Ariane did not explode, it disintegrated due to high dynamic pressure!?! Roger ---------------------------------------------------------------------------- Roger W. Fischer fischer@mprgate.mpr.ca fischer@mprgate.UUCP ..seismo!ubc-cs!mprgate!fischer ...ihnp4!alberta!ubc-cs!mprgate!fischer ------------------------------ Date: 1 Mar 90 16:33:45 GMT From: mcsun!ukc!inmos!conor%wren.inmos.co.uk@uunet.uu.net (Conor O'Neill) Subject: Re: SPACE Digest V11 #80 In article TROTTA@steffi.acc.uncg.edu (Platypi go 'Quack!') writes: >Does anyone know the coordenats for the center of the Galaxy? >Including right acclination. >Tahnks >Trotta@uncg.bitnet Surely they are (0, 0, 0) Conor O'Neill, Software Group, INMOS Ltd., UK. UK: conor@inmos.co.uk US: conor@inmos.com "It's state-of-the-art" "But it doesn't work!" "That is the state-of-the-art". ------------------------------ End of SPACE Digest V11 #105 *******************