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, 5 Jun 91 02:47:30 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 5 Jun 91 02:47:26 -0400 (EDT) Subject: SPACE Digest V13 #602 SPACE Digest Volume 13 : Issue 602 Today's Topics: Re: Should Galileo be rerouted? Re: Fred vs. Exploration: head-to-head competition Re: Saturn V and the ALS lifeboats Re: Fred cut, AXAF and SIRTF funded What can be done without government interference Re: Tethers (was Re: Laser launchers) MAJOR SOLAR FLARE ALERT - PROTON IMPACT POSSIBLE 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: 18 May 91 17:48:37 GMT From: snorkelwacker.mit.edu!spool.mu.edu!munnari.oz.au!uhccux!tholen@bloom-beacon.mit.edu (David Tholen) Subject: Re: Should Galileo be rerouted? Henry Spencer writes: > There is, however, a small problem in that the probability of good results > from the asteroid encounter(s) is much higher if optical navigation is > available during the approach. The asteroids' positions simply are not > known all that accurately. Without the main antenna to send approach > images back to Earth quickly, the cameras will have to be pointed by > guesswork. My recollection is that the imaging people were worried enough > about pointing *before* the antenna problem appeared... Optical navigation will still be done, though the last image will be obtained five days out instead of one day out; it takes four days to play back an image. Groundbased astrometry has taken on added importance as a result, and we are working at beefing up our monitoring. We've measured Gaspra's position three times this past week and hope to continue with weekly measurements. Even so, the error ellipse will likely be large enough to result in some fraction of blank images. Yes, this was true even before the antenna problem developed. We are working to minimize the number of blank frames. ------------------------------ Date: 18 May 91 21:24:42 GMT From: sdd.hp.com!think.com!rpi!news-server.csri.toronto.edu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Fred vs. Exploration: head-to-head competition In article <1991May18.075914.19824@sequent.com> szabo@sequent.com writes: >>The "funding" to which *you* were referring was the hypothetical $10G >>peak Fred budget. I stand by my comments: no space project will ever >>see that money if Fred dies. > >You don't ignore my postings, you fail to read them correctly. >I was in fact referring to the _current_ saving of SIRTF and AXAF >by the cutting of Fred in the Congressional committee... Ah, so that's why your attention span is so short: your memory is going. To quote <1991May16.090453.2293@sequent.com>: > Even a _momentary_ effect is enough to pay for SIRTF, AXAF, > a greatly expanded ground-based visual search, a greatly expanded > Antartic asteroid sample return mission, _and_ a gaggle > of small infrared probes launched into the meteor showers. > > That's right, _all_ of that, spread over several years, costs just > one year of peak Fred funding (c. $10 billion by GAO estimates). No, Nick, a momentary effect won't pay for these things... unless that "momentary" effect somehow gives planetary science at least the equivalent of a year of Fred's supposed peak funding, as you suggested. Dream on. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 19 May 91 02:59:32 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!samsung!umich!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: Saturn V and the ALS In article <1991May19.010222.17491@agate.berkeley.edu> fcrary@lightning.Berkeley.EDU (Frank Crary) writes: >>That figure came from the LLNL Great Exploration Study. Their station >>cost about $1 billion. I doubled it. >The costs and schedules in LLNL's Great Exploration are questionable. They >reduce launch costs by having the government offer to pay $250/lb (or >a similar figure) for supplies transported to orbit. The figure is closer to $1,000/lb which I do not consider a similar figure. They have two contractors who agree to provide launch services for that price. Even if they cannot, this has little effect on the LLNL Space Station since it only requires one HLV launch. >high rates, using new-and-cheaper launchers within two years. I have their schedule in front of me (LLNL doc 90-402) and it has the first launch at just under three years after program start. This is compatable with the schedules Martin and McDonnell gave SDIO for the Zenith Star HLV's. >They also >assume "success oriented planning" that is, that everything will work as >planned and on budget, with no money spent on contingencies or any margin >for error. Actually, I think they have very wide margins for error. However, you will note that I have doubled the cost of both the HLV development AND the station development. It still comes in cheaper then flying the Shuttle for a year. >These are EXTREMELY optimistic assumptions. Both the NASA work on inflatables and the study by a major NASA contractor with similar experience (ILC Dover) say the approach is workable within existing technology. >I was refering, rather, to the guidance and control systems (no to mention >manuevering rockets and fuel) needed to approch and dock to the station. You are correct here. They will need the HLV to go up and let's tack on $1B for the modifications (about the cost of the original Spacelab development). In that case it may take a bit more than one years Shuttle savings to pay for it. We are still getting hundreds of times more science for far far less cost. >>Some are designed to have components replaced. Remember Solar Max? >Designing them in this way drives up their mass. The HLV which results from this program reduces cost to LEO by a factor of three. That should make up for any extra mass. If not, the extended lifetime should. >In any case, are you assuming >that the only on orbit repairs will be the replacement of failed "black-boxes" >with the new parts shipped up from Earth. (Not a bad assumption, but I had >the impression you meant something more...) Eventually I do but it needs to be bootstraped. Eventually we will do all the integration in space. This will reduce cost and add to reliability. If Galelio where integrated in space it would have gone directly to Jupiter. In addition, it wouldn't need all the complex mhanisms used to unfold its antenna. A direct result of this would be people at JPL getting a lot more sleep. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | Allen's tactics are too tricky to deal with | | aws@iti.org | -- Harel Barzilai | +---------------------------------------------------------------------------+ ------------------------------ Date: 19 May 91 02:36:24 GMT From: swrinde!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: lifeboats In article <1991May18.233449.10542@agate.berkeley.edu> fcrary@lightning.Berkeley.EDU (Frank Crary) writes: >I don't think the command module alone could serve as a crew transport. Such >a transport would require at least 48 hours of autonomus power and life >support capability ... If I remember correctly, the >Apollo CM has almost NO independent capability (e.g. it needs a service >module, execpt for a very short time before and during reentry.) Adding power and life support should be a simple matter of another battery or two and another tank or two. The CM had plenty of equipment that would be largely superfluous in this role, so there should be no serious problem finding room and mass for such minor changes. The one SM function that would have to be provided by new hardware would be retrofire. The obvious method is a set of small solid motors a la Gemini. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 19 May 91 03:49:12 GMT From: sdd.hp.com!spool.mu.edu!uwm.edu!linac!unixhub!slacvm!doctorj@ucsd.edu (Jon J Thaler) Subject: Re: Fred cut, AXAF and SIRTF funded In article <1991May19.012452.19374@agate.berkeley.edu>, fcrary@lightning.Berkeley.EDU (Frank Crary) says: [...stuff deleted...] > In no way does this mean that these programs benifited from >Freedom being zeroed. It means that they were not hurt because of it. There >is a BIG difference between gaining money and not loosing money. (If your >boss does not give you a raise, could you say that he gave you money, since >he chose not to fire you?) It seems to me that the two sides in this argument are talking about two different things. My understanding of the history of the budget is (I'm sure I'll be corrected if I'm wrong): * When the budget was submitted: The President's budget is (as usual) declared "dead on arrival," because his spending priorities are not the same as the Democrats'. At this point, there isn't necessarily a one-or-the-other choice to be made about space projects. * Last week: The total NASA budget had already been (more-or-less) determined, and the vote was on how to allocate $700 million or so of money. This was directly a this-or-that choice. So, the two sides are talking about the budget as it existed at two different times. ------------------------------ Date: 19 May 91 14:38:16 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!spool.mu.edu!news.nd.edu!mentor.cc.purdue.edu!pop.stat.purdue.edu!hrubin@tut.cis.ohio-state.edu (Herman Rubin) Subject: What can be done without government interference In article <1991May18.182710.16880@iti.org>, aws@iti.org (Allen W. Sherzer) writes: > In article <1991May18.071631.19572@sequent.com> szabo@sequent.com writes: > > >>There is a middle ground between our current socialistic approach and > >>total government non-involvement (nither of which will work IMHO). > > >We've never tried a totally non-government approach, actually, so > >it is hard to say how it would turn out. > > No large infrastructure project has ever been done without major > government involvement. I disagree. I do not know of any, although I believe that even some of thes must have occurred, without government acquiescence, but certainly there have been many without government involvement. That is, unless you consider setting up an infrastructure, or even a government, involvement of the original government. The Massachusetts Bay Colony was set up by the Puritans, with at most grudging acceptance by the British Government. I doubt that when Roger Williams founded Rhode Island he had any government backing. On a different note, we have the Amish, Shaker, and other religious communities in the US and elsewhere. We have the kibbutzim in Israel, many started well before a separate state; these are, in many cases, the size of towns. Also, it is clear that the Mormons did not have government backing when they settled in Utah. We have the development of the clipper ships in the 19th century. The gold rush occurred before the government could even get organized. The taking over of India by the British, including the setting up of a massive infrastructure, was done by the British East India Company, NOT a branch of the British government, although the British military cooperated. Only later did the British government get in. There are millions who support major space activities. I do not say that some organization is not needed, but anything more than permission from existing governments is unnecessary. -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399 Phone: (317)494-6054 hrubin@l.cc.purdue.edu (Internet, bitnet) {purdue,pur-ee}!l.cc!hrubin(UUCP) ------------------------------ Date: 19 May 91 07:28:36 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!news-server.csri.toronto.edu!torsqnt!hybrid!torag!w-dnes!waltdnes@tut.cis.ohio-state.edu (Walter Dnes ) Subject: Re: Tethers (was Re: Laser launchers) neufeld@aurora.physics.utoronto.ca (Christopher Neufeld) writes: > In article <2817@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: > > > >Let's look at a typical strawman tether launch. Let's propose a 1000 km > >tether whose center of mass is in a 700 km orbit. To hook on to the > >lower end of the tether, you need to be going faster than the orbital > >velocity of a 700 km orbit and be at an altitude of 200 km. If you've > >already gone that far, you've paid most of the cost to orbit. > > > No, that's not right. If the tether is rotating, resembling the spoke > of an invisible wheel rolling around the surface of the Earth, then the > velocity of the tip drops to zero briefly. A person standing on the > ground would see the tether come in from a high angle, straightening out > until it was coming straight down, stop, then take off in the upward > "If the tether is rotating..." W-H-O-A !!!!!!!!!!!!!!!!!! ( w = omega, MS-DOS can handle it but other character sets are different. ) Let's see... orbital velocity is approximately 7 km/sec at that altitude. Assuming that the tether is as above, you've got 500 km of tether rotating with the end moving at 7 km/sec. wr = v v 7 w = - = --- = 0.014 radians/sec r 500 A small section length dr will have mass kdr where k is the linear density. a = v * v / r = w * w * r at any radius r. Let's assume a cable of material X (neutronium ?) The 500 km section would have a centrifugal/centripital tug of... /~ 500 km /~ 500 km Ascii | | k(wr)^2 evaluated at integral F = | ma = kw^2 | r dr = ------- r = 500 km sign _/ _/ 2 0 km 0 km But we started off with wr = 7 km/sec, so we're looking at k(wr)^2 k(7km/sec)^2 k(49000000m^2) k(24500000)m^2 ------- = ------------ = -------------- = -------------- 2 2 2sec^2 sec^2 k(500000m)*49m = --------------- sec^2 but 500000m = 500km since k is the linear density k(500000)m = mass of the 500km section of tether 49m/sec^2 = approx 5 g's This is one half of the tether. Newton's 3rd law implies that the other portion has identical force *IN THE OTHER DIRECTION*. Also 5 times the earth-surface weight of the tether. And we were worrying about whether the tether would hold up under its own weight. At this point gravitational force becomes a secondary mechanism in the process of tearing the structure apart. Back to the drawing board... Walter Dnes -------------------------------------------------------------------------- waltdnes@w-dnes.UUCP waltdnes%w-dnes@torag.UUCP ...hybrid!torag!w-dnes!waltdnes 73710.3066@compuserve.com ------------------------------ Date: Sat, 18 May 91 01:14:49 MDT From: oler <@BITNET.CC.CMU.EDU:oler@HG.ULeth.CA> (CARY OLER) Subject: MAJOR SOLAR FLARE ALERT - PROTON IMPACT POSSIBLE X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" -- MAJOR SOLAR FLARE ALERT -- MAY 18, 1991 Potential Proton Impact Flare Event Summary Potential Impact Assessment -------- MAJOR ENERGETIC EVENT SUMMARY A major energetic flare erupted from Region 6619 early in the UT day of 18 May. The event began at 04:37 UT, peaked at 05:45 UT and has not yet ended as of this writing (06:40 UT). This event was rated a powerful class X2.8/1N Tenflare, and was unusually long in duration. The integrated x-ray flux from this flare is high, rated so far at near 1.00 Joules/meter^2. A moderate intensity Type II sweep was observed together with a weak Type IV. The 2695 MHz emission was measured at 5,700 s.f.u.. The flare was located at N32W84 and may have ejected protons. These figures are preliminary. There is a moderate risk for a satellite proton event to begin near 16:00 UT on 18 May. Proton levels could exceed 200 p.f.u. at that time. Polar latitudes are alerted to the potential for minor PCA activity and/or a polar cap disturbance affecting polar radio communications and navigational systems. Increased levels of absorption could introduce errors in navigational signals passing through or near the polar latitudes. If a flare shock arrives from the previous class M8.9 major flare of 16 May (which is expected sometime near 12:00 UT on 18 May), the latitudinal boundary of polar ionospheric absorption could migrate equatorward, affecting a larger area than might normally be expected. Radio communicators and navigators should be aware of the increased threat for proton-related disturbances. Region 6619 maintained a stable configuration since the last major class M8.9/2B flare of 16 May. No change in size or apparent spot configuration was observed during the period prior to this major X-class flare. POTENTIAL TERRESTRIAL IMPACT ASSESSMENT Aside from the possible proton impact mentioned above, no significant terrestrial geomagnetic impacts are expected from this event. Region 6619 is very near the west limb and will be out of view on 19 May. This region will still remain capable of producing terrestrial flare-effects (SIDs/SWFs and proton activity) until it rotates further beyond the west limb. The Potential Major Solar Flare Warning will remain in effect until further notice. The other regions currently visible are not capable of producing major flare activity. At best, only isolated low-level M-class flares will be possible from these regions, with a higher probability for C-class flares. Once Region 6619 rotates beyond the west limb and out of influential range, solar activity will likely return to low levels, with occassional periods of moderate activity. WARNINGS CURRENTLY IN PROGRESS: - POTENTIAL GEOMAGNETIC STORM WARNING (18-19 MAY) - LOW LATITUDE AURORAL ACTIVITY WATCH (18-19 MAY) - POTENTIAL MAJOR SOLAR FLARE WARNING ** End of Alert ** ------------------------------ End of SPACE Digest V13 #602 *******************