Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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 ; Wed, 20 Mar 91 02:34:19 -0500 (EST) Message-ID: <4btl1qe00WBwM5VE5Y@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 20 Mar 91 02:34:15 -0500 (EST) Subject: SPACE Digest V13 #285 SPACE Digest Volume 13 : Issue 285 Today's Topics: Re: Reliability Re: New World Profits (was Re: Space Profits Re: Thrust Re: Galileo Update - 03/18/91 Re: German conference highlights doubts about ESA's manned space plans MAJOR SOLAR FLARE ALERT - 16 MARCH - EVENT #2 Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 13 Mar 91 11:29:00 GMT From: sdd.hp.com!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!think.com!linus!philabs!ttidca!quad1!bohica!mcws!p0.f851.n102.z1.fidonet.org!John.Roberts@ucsd.edu (John Roberts) Subject: Re: Reliability From: roberts@CMR.NCSL.NIST.GOV (John Roberts) Path: wciu!elroy.jpl.nasa.gov!decwrl!ucbvax!CMR.NCSL.NIST.GOV!roberts Newsgroups: sci.space Subject: Re: Reliability Message-ID: <9103130329.AA14348@cmr.ncsl.nist.gov> Date: 13 Mar 91 03:29:24 GMT >Date: 11 Mar 91 22:59:56 GMT >From: news-server.csri.toronto.edu!utzoo!henry@rutgers.edu (Henry Spencer) >Subject: Re: Reliability >In article <9103090139.AA04460@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >>>peculiar myth within NASA that all possible problems can be anticipated, >>>and you really can be certain that the thing will work before you launch it. >>>The universe keeps trying to tell NASA that this is wrong... >> >>That last statement sounds a little too broad. Just about everything they >>launch is chock full of backup systems, and the unmanned devices have both >>on-board recovery systems and provision for ground-based reconfiguration. >All of which can handle only expected classes of failures, by and large. It's generally not practical to be completely prepared for the completely unexpected. The best one can hope for is to think of as many contingencies as possible. Of course, it's also the duty of the designers to put priority on solving the problems deemed most likely to cause trouble. >On-board recovery systems and provision for reconfiguration are of limited >help if your thrusters explode when fired continuously... and we very nearly >sent Galileo up with thrusters that did exactly that. In a way, we did. Those same thrusters are still in there. They haven't exploded, however. >(The thruster problem >was discovered only because TVSat 1 used the same thrusters, and it fired >them long and hard in attempts to shake its stuck solar array loose. Had >Galileo been launched on schedule, it would have been very lucky to reach >Jupiter. TVSat 1 went up during the post-Challenger hiatus.) And other things that have not received as much publicity. For instance, the original design would *probably* (> 50%) have failed before or during the time-critical Jupiter insertion due to radiation-induced computer errors. An effort was made to greatly increase the radiation hardening, and such an event is now considered very unlikely. >On-board recovery systems and provision for reconfiguration are of limited >use if your solar arrays flap every time you cross from sunlight into >darkness... last I heard the HST people had given up on ever being able >to get full compensation for this, as the onboard systems just don't have >enough crunch. It would be unfair to also mention the mirror-distortion >actuators that don't have enough muscle to take the spherical aberration >out, so I won't :-). Since you didn't mention it, I won't reply that HST was designed for repair (quite a bit of it, anyway) by visiting astronauts. :-) :-) >On-board recovery systems and provision for reconfiguration didn't save >Seasat, or the Viking 1 lander, or the attitude-control system on Solar Max >either. All of these things deal only with expected classes of problems. >They can still be blind-sided by something unexpected. Viking had very poor on-board recovery by modern standards - no command loss timer or reacquisition software. (Did it even have a low gain antenna?) The Voyagers were launched before the Viking loss, yet they have these features, though possibly only in software. (Trivia question: what was the last US interplanetary probe launched that could not be reprogrammed from Earth?) >>If you're thinking of simpler multiple probes, I think that has both good >>and bad points, and has to be evaluated on the merits of each case... >Simplicity vs. multiple missions is a complex tradeoff. But putting all >your eggs in one basket is foolish whether that basket is simple *or* >complex, because *failures do happen*. Complex systems, while often >better equipped to cope with failures, also are more prone to them. >"But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology >for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry To get back to your original comment, what can NASA *do* that's better than what it's been doing? If they build multiple probes for a multiyear mission, should they launch all of them at once, and possibly let the same unforeseen design problem zap all of them? Or should they keep some on Earth, and put up with the heat about overspending and probes that could have been used gathering dust in museums? If there's plenty of money, they can do both - launch probes every year or two, with nearly duplicate missions, and retargetable in the event of failures. Voyager came close to that - missions some months apart, plus one gathering dust. For the absolute minimum in eggmonobasketing, perhaps in many cases the best approach is what NASA has apparently done with Magellan, Galileo, etc.: for each project, build *one* probe for launch, designed to be as resilient as possible, and do everything you can to keep it alive. If problems start to come up, begin thinking about what you could have done better. If the mission fails, do your utmost to find out why it happened (NASA seems very good at this), then start begging for money for another probe. That way, when you start construction of the replacement, you know what pitfalls to avoid, and you can eliminate design problems that have turned up in the interim. (The thruster problem was known *before* Galileo was launched, but at that point it was too expensive to make changes other than in the operational algorithm. These changes do decrease performance somewhat.) Furthermore, the development of technology is on your side - there may be new and better ways to do it. In the meantime, you spread your money over a wide range of projects, so even if on project suffers a major setback, you still have valuable results coming in from the other projects. Yes, there is at least one major drawback to this approach - if the one probe fails, the team put together to control and use it must disband for a number of years (or at least cut way back on its activity) while the replacement is being built. The "standard probe" utilization that you have advocated would help to reduce this interval. John Roberts roberts@cmr.ncsl.nist.gov -- : John Roberts - via FidoNet node 1:102/851 (818)352-2993 : ARPA/INTERNET: John.Roberts@p0.f851.n102.z1.fidonet.org : UUCP: ...!{elroy!bohica,elroy!wciu,cit-vax!wciu}!mcws!851.0!John.Roberts : Compu$erve: >internet:John.Roberts@p0.f851.n102.z1.fidonet.org ------------------------------ Date: 13 Mar 91 19:58:00 GMT From: agate!linus!philabs!ttidca!quad1!bohica!mcws!p0.f851.n102.z1.fidonet.org!Unknown@ucbvax.Berkeley.EDU (Unknown) Subject: Re: New World Profits (was Re: Space Profits From: GIPP@gecrdvm1.crd.ge.com Path: wciu!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!rpi!crdgw1!gecrdvm1!gipp Newsgroups: sci.space Subject: Re: New World Profits (was Re: Space Profits Message-ID: <91072.075847GIPP@GECRDVM1.BITNET> Date: 13 Mar 91 11:58:47 GMT In article <5385@wrgate.WR.TEK.COM>, dant@mtdoom.WR.TEK.COM (Dan Tilque) says: > >bdietz@sdcc13.ucsd.edu (Jack Dietz) writes: >> >>In article <5370@wrgate.WR.TEK.COM> Dan Tilque writes: >> >>>slower rate or even halted altogether. However, Columbus knew >>>this and kept exploring until he had at least something valuable to >>>show for his trip. >> >>This implies that Columbus was exploring what he thought was unprofitable >>land. In other words, he was using the money of the Spanish crown in >>order to satisfy his desire to explore, not in the interests of the >>royal pair. > > >>Interesting. If only our explorers could pull something like that >>off, leading Congress on while they encourage exploitation... > >NASA administrators are good at something like this. It's a required >ability of higher level bureaucrats. > >--- It's the state of R&D in the US: Bullshit about what you've "almost" got your hands on, and get the company (or even better-the gov't) to pay for the next "trip" (also known as next years budget). the name of the game isn't to invent, but to spend money and write papers. Doesn't matter if you invent, the company usually doesn't know what to do with it anyway! Pete (I damn well better put a disclaimer on this one) Gipp all opinions here are mine and do not reflect the views of any company I work for or know of "nobody knows anyone at all, strangers in paradise down at the mall, everybody needs a home"....Iggy -- : Unknown - via FidoNet node 1:102/851 (818)352-2993 : ARPA/INTERNET: Unknown@p0.f851.n102.z1.fidonet.org : UUCP: ...!{elroy!bohica,elroy!wciu,cit-vax!wciu}!mcws!851.0!Unknown : Compu$erve: >internet:Unknown@p0.f851.n102.z1.fidonet.org ------------------------------ Date: 11 Mar 91 11:20:00 GMT From: agate!linus!philabs!ttidca!quad1!bohica!mcws!p0.f851.n102.z1.fidonet.org!Nick.Szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: Thrust From: szabo@crg5.UUCP (Nick Szabo) Path: wciu!elroy.jpl.nasa.gov!usc!zaphod.mps.ohio-state.edu!wuarchive!uunet!zephyr.ens.tek.com!tektronix!sequent!crg5!szabo Newsgroups: sci.space Subject: Re: Thrust Message-ID: <21319@crg5.UUCP> Date: 11 Mar 91 03:20:23 GMT In article <9103090236.AA04603@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >Another method that has been mentioned is launching water from Earth, then >using solar energy to convert it to hydrogen and oxygen for use in a >conventional engine. Because of its greater density, the water should be >much cheaper to launch than LOX/LH2. Much cheaper, for high volumes, would be to capture a small burned-out comet and launch low-mass mining and processing equipment (ice is much easier to deal with than rock). It would take two or three Delta launches ($80-$120 million) to deliver 100 million kg into GEO or higher orbit. This gives us $1/kg plus the cost of upper stage, retreival, and mining equipment. Capture is accomplished via gravity assist and/or aerobraking, with a small mass driver for fine-tuning. The scientific and technological prerequisites are: * We need to develop low-mass (<1 Delta payload) mining equipment that can operate in microgravity and vacuum to process methane and water ice with a small surface layer of tar, dust, and rock; * We need to increase our tracking of near-earth asteroids from <0.1% to at least 10% of the c. 100,000 in the size range above 100m. The water and methane can be moved to LEO, and used directly as reaction mass for solar or nuclear thermal rockets. The water can also be electrolyzed into hydrogen and oxygen for use in chemical rockets. These volatiles could also be used for life support, shielding, and might provide raw materials for larger-scale space manufacturing. >It might be possible to save even >more money by using an exotic launch method such as linear or laser launch. >(How 'bout that, Nick?) This would be very valuable for cargo that cannot be easily mined (all cargo for now). I urge NASA and government labs that want in on space to get to work on advanced launch options. Both of these cases provide clear examples of why both basic science (in this case, astronomy) and advanced technology research are so important to space development, and why setting narrowly defined goals must be avoided. -- Nick Szabo szabo@sequent.com "What are the _facts_, and to how many decimal places?" -- RAH -- : Nick Szabo - via FidoNet node 1:102/851 (818)352-2993 : ARPA/INTERNET: Nick.Szabo@p0.f851.n102.z1.fidonet.org : UUCP: ...!{elroy!bohica,elroy!wciu,cit-vax!wciu}!mcws!851.0!Nick.Szabo : Compu$erve: >internet:Nick.Szabo@p0.f851.n102.z1.fidonet.org ------------------------------ Date: 19 Mar 91 01:41:21 GMT From: uhccux!tholen@ames.arc.nasa.gov (David Tholen) Subject: Re: Galileo Update - 03/18/91 > Galileo will be the first spacecraft to fly by an asteroid when it > approaches within about 1,000 miles of the irregularly shaped, stony lump > measuring nearly 15 miles across. During the encounter, the spacecraft will Probably meant to say 15 kilometers across. The published catalog of IRAS detections of asteroids shows one successful observation of Gaspra, and that indicates an effective diameter of 15.5 km. However, I understand that the latest orbit for Gaspra has shifted its expected position on the IRAS detectors toward the edge, meaning that the quality of the measurement is now in question. In addition, Gaspra has a fairly substantial rotational lightcurve variation, indicating an elongated shape, and nobody knows at what point in the rotational lightcurve the IRAS observation was made, so the stated diameter is rather uncertain. The range of 1,000 miles is correct, so if the true effective diameter is indeed about 15 km, then Gaspra will slightly overfill the Galileo camera field of view. ------------------------------ Date: 15 Mar 91 18:20:41 GMT From: agate!bionet!uwm.edu!rpi!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: German conference highlights doubts about ESA's manned space plans [re robots vs humans in repairing space vehicles in orbit] reply to posting by Andreas G. Nowatzyk AG> Hardware that isn't designed for this, will require a very AG> elaborate robot. However if the design takes robotic service AG> into account, things change dramatically. For example, a lot of AG> consumer equipment (VCRs & such) and some computer gear (Mac's, AG> printers, etc.) are now routinely designed for robotic AG> assembly.... Yes but there's a significant difference between designing something to be ASSEMBLED by a robot and designing it to be FIXED by one. In general, If you want it to be repairable robotically, the cost will go up. Don't forget the cost of the robot in the first place, anything that has the abilities of a human will cost mucho bucks. Besides, there will always be those situations that robots are not able to handle. You mentioned Solar Max; wasn't it spinning? I remember the astronaut having to do some unconventional maneuvers to catch the thing. I imagine that much will be done in space by both robots and telefactors. However, we shouldn't limit ourselves too much. --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: Sun, 17 Mar 91 01:28:51 MST From: oler%HG.ULeth.CA@vma.cc.cmu.edu (CARY OLER) Subject: MAJOR SOLAR FLARE ALERT - 16 MARCH - EVENT #2 X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" -- MAJOR SOLAR FLARE ALERT -- MARCH 16, 1991 Alert #2 Flare Event Summary Potential Impact Assessment -------- MAJOR ENERGETIC EVENT SUMMARY Region 6545 continues to produce major flares. Another major flare occurred at 21:58 UT on 16 March. This flare began at 21:52 UT, peaked at 21:58 UT and ended at 22:15 UT on 16 March. The intensity achieved was a class M6.0/2B rating with an associated 400 s.f.u. tenflare. Radio emissions were again fairly rich, although not as intense as in previous X-class flares from this region. The intensity at 245 MHz reached 10,000 s.f.u.. The location of this flare was S09W04. Region 6545 continues to exhibit a moderate amount of magnetic complexity. It maintains a beta-gamma-delta configuration and contains a fair amount of shear. This region has spawned numerous minor M-class flares over the past 24 hours, including an M4.8/1B at 10:54 UT on 16 March. A proton enhancement continues at the present time, together with a small Forbush decrease which was first observed on 12/13 March coinciding with an interplanetary shock (of uncertain origin) and a following brief period of major magnetic storming. POTENTIAL TERRESTRIAL IMPACT ASSESSMENT No terrestrial impact is expected from the most recent M6.0/2B tenflare. This flare was not associated with any sweeps and does not pose much of a threat. There is concern, however, regarding the potential impacts of the recent class X1.8/2B tenflare with associated strong Type II and IV sweeps which occurred at 00:16 UT on 16 March. There is uncertainty among forecasters regarding this event. At the present time, a light to moderate impact is expected late on 17 March or on 18 March. Minor storming is expected for the high latitudes and northerly middle latitudes. No major storming is expected. But given the recent unpredictability of events and uncertainty present among the forecasting community, confidence levels are not very high with regards to the possible accuracy of these predictions. The one area where there is a strong consensus is with regards to the possibility for proton and PCA activity. There is a fairly high probability (now near 50%) that a major energetic flare could produce proton and PCA activity, particularly since the proton levels are already elevated near event thresholds. A condition YELLOW alert status will remain in place for possible PCA activity. Polar regions should be on the alert for possible flare-induced PCA activity. Radio communicators should be aware of the elevated risk for polar blackout conditions on HF polar paths should solar protons produce PCA activity. Further major flare alerts will be posted as needed. For an update on the status of the warnings, consult the recent Solar Terrestrial Bulletin for 06:00 UT on 17 March. ** End of Alert ** ------------------------------ End of SPACE Digest V13 #285 *******************