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 ; Sat, 29 Jun 91 05:22:37 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 29 Jun 91 05:22:32 -0400 (EDT) Subject: SPACE Digest V13 #745 SPACE Digest Volume 13 : Issue 745 Today's Topics: Re: Dark matter Re: Slingshot effect Re: The economics of flooding a market Re: Mars or bust! Re: Stafford Commission Report Re: Excavating (mining) gold in the space by NASA. Re: Space Link Re: Mars or bust! 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: 15 Jun 91 03:11:34 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!m.cs.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu!tbm19061@ucbvax.Berkeley.EDU (Thomas B MacIukenas) Subject: Re: Dark matter lev@slced1.nswses.navy.mil (Lloyd E Vancil) writes: >And I was wondering, why cant "dark matter" be planets, rocks, comets, etc etc? > Just a question... Well, let's see-- Planets. These are only a small fraction of the mass of solar systems, which are already accounted for, so they can't be the dark matter. Rocks. I don't see any reason why not. Comets. These are just rocks which get too close to stars, so the same comment applies. The only thing I can think of is that since rocks/comets are formed of matter which comes from dead suns, maybe what we know about star life cycles says that not enough rocky material could have been formed already. -- __ ____ ____ ________ __ __ __ __tbm19061@uxa.cso.uiuc.edu_________________ \_ _\ _ \ _ _ \ \ \ \ "Does the falcon a creature of the skies \ \ \ \ \ \ \__\__\__\ Mourn the passing of it's prize?" ______\__ \____\__\__\__\__\__\__\____________________-Animator____________ ------------------------------ Date: 15 Jun 91 03:21:46 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!think.com!spool.mu.edu!snorkelwacker.mit.edu!news.media.mit.edu!media-lab.media.mit.edu!minsky@ucbvax.Berkeley.EDU (Marvin Minsky) Subject: Re: Slingshot effect In article la_carle@sol.brispoly.ac.uk (Les Carleton) writes: > >Can you please explain the "slingshot" effect as used on recent >probes. I understand that it increases the velocity of the vehicle by >making passes around the sun. I'm not a physics or Astrophysics major >so it may seem a naiive question. What I don't understand is why the >velocity increases. Surely if a pass of the sun is made, the energy >conservation law will come into play and the vehicle will end up with >the same velocity at its original distance from the sun as it had when >left there (after launch?). When a probe passes around a planet the effect is a bit like bouncing off the planet and, if the planet is coming toward you then you will leave with (in the limit, which requires a very close passage) an additional twice the relative velocity. However, for planetary visits, bouncing off the sun is no use because it has zero velocity with respect to the solar system, more or less by definition. Nevertheless it can be very useful for changing your direction without comsuning any fuel. And also there's another way to use the sun, if you're carrying fuel: fall into the sun and fire the rockets at perigee. The fuel has gained potential energy in the fall, and you don't have to carry it ------------------------------ Date: 15 Jun 91 03:27:54 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!ub!galileo.cc.rochester.edu!rochester!dietz@ucbvax.Berkeley.EDU (Paul Dietz) Subject: Re: The economics of flooding a market In article <1991Jun14.223648.17095@sequent.com> szabo@sequent.com writes: > increases faster than its price decreases. For example, there are > greater revenues from corn, wheat, iron, oil etc. in our economy today > even though the per unit prices of these are lower than in previous > centuries. For platinum, this will probably also be true, since it is > widely used in oil refining, environmental cleanup technology, and > other important industrial applications.A drop in price could increase > demand by a much larger factor. One very interesting application of platinum would be in fuel cells. For a variety of reasons, cheap platinum would make fuel cell powerplants for electric vehicles considerably more practical. In particular, one could use a direct methanol/air fuel cell, avoiding the need to handle hydrogen, scrub air of CO2, or thermally reform the methanol. Ford was looking at methonal/air fuel cells some years back, but abandoned the effort when they could not reduce the platinum loading requirements enough for it to be economical. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 14 Jun 91 13:56:42 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: Mars or bust! In article <1991Jun13.115140.3962@waikato.ac.nz> pjs1@waikato.ac.nz writes: > Could any one tell me how to get hold of a copy. Note that I'm in New >Zealand so there may be some export of technology problems I doubt very much that there are any ITAR restrictions on the report so you should have no trouble. >We won't >take your nuclear ships and you want to give them to us :-). Hmmm... they are proposing nuclear rockets. I would say to get a copy write to the Synthesis Group at: Synthisis Group 1225 Jefferson Davis Highway Suite 1501 Arlington VA 22202 US citizens should write or call their senators or representative. If you go through them I suspect you can get it for free. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ Date: 14 Jun 91 14:21:33 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!malgudi!caen!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: Stafford Commission Report In article <1991Jun13.163927.28205@sequent.com> szabo@sequent.com writes: >* The panel was dominated by Apollo-era astronauts and engineers. So? They are all competent engineers well qualified to do the work. >* The panel made the the first recommendation in any major > space commission report that the earth-crossing asteroids could > also be a good target for astronaut and automated exploration. > The Plan does change, even if much more slowly than the real > world. I'll take good news wherever it comes from. These quys want to make extensive use of extra-terestrial resources. Earth-crossing asteroids are a good source. They will also be using trips to these asteroids as their 'Apollo 8'. It will be a test run for Mars and demostrate the ability to operate outside the Earth-moon system. >* The group recommended revival of Saturn/Apollo technology, as > has been discussed in this newsgroup. What can I say? Great minds think alike :). >Aside from some details (nuclear power, asteroids) these guys are >still living in the 60's, I'm afraid. They are using 60's technology because that is what works best and cheapest. A desire to use the cheapest technology and then continuously improve it is not 'living in the 60's'. >Geezers rocking back and >forth on the patio, reminiscing about the good ol' days, when >rockets were big, budgets were bigger, and astronauts had the >Right Stuff. Thanks for the memories, gramps. :-)... You concluded all that from a two paragraph summary of a 180 page document? Would it be too much to ask that you actually read it before forming an opinion about it? >Any real space buff is also worried about the costs. What makes you think they aren't? I have spoken with Synthesis people and others connected with them. They are ALL concerned with reducing cost. >>"It's no accident there are no dollars attached to it," said John E. >>Pike, associate director for space policy at the Federation of >>American sientists. "People would have sticker shock at the price." There are a number of good estimates far below the commonly given estimates. It can be done for less than the cost of Freedom. >I reccomend yesterday's Wall Street Journal and this week's Aviation >Week & Space Technology for more complete coverage of the report. You might also get and read the report itself. Of course, those who prefer to make up their minds in advance can skip this step. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ Date: 14 Jun 91 20:59:30 GMT From: mojo!SYSMGR%KING.ENG.UMD.EDU@mimsy.umd.edu (Doug Mohney) Subject: Re: Excavating (mining) gold in the space by NASA. {I hate to do this but.....} In article <1991Jun14.183424.654@noose.ecn.purdue.edu>, G E Derylo writes: > > Today's Washington Post reports that an asteroid has been found orbiting the >Sun at a distance of about 20 million miles from Earth (closest point). It >apparently contains 10000 tons of gold and 100000 tons of platinum, as well as > > I'm no economist, but wouldn't the introduction of that much gold and >platinum into the market *drastically* decrease its value, making this a >questionable financial venture? Sure, I know these materials also have crutial >industrial applications, so we're not just dealing with jewelry here. Yes, it would. But then people would do all kinda nifty things with gold and platinum, assuming the refined stuff came back in one piece. >tomarrow in the middle of Nebraska, would do really nastiy things to our >gold-based (?) economy. We ditched the Gold Standard years ago. Our currency (as well as those of many other nations) operates on a "floating" principle of trade in relation to other nation's supply and demand for our greenbacks (and us for their currency). I'm not sure any country has its cash backed by gold these days. The Soviets are looking at backing the ruble in this fashion but they will prob'ly peg their currency to the Yankee Dollar or let it float as well. I do not have my econ texts at hand, so you only get the Reader's Digest version here.... Signature envy: quality of some people to put 24+ lines in their .sigs -- > SYSMGR@CADLAB.ENG.UMD.EDU < -- ------------------------------ Date: 14 Jun 91 10:47:29 GMT From: mcsun!hp4nl!sara5!hasara11!a6014bb@uunet.uu.net Subject: Re: Space Link You can also try ames.arc.nasa.gov anonymous entry it's got lot's of astro-stuff including software and text/gif Also the space link directory: pub\SPACE\SPACELINK get the index first before you list this directory since it takes ages (it's DAMN long...) Bjorn ------------------------------ Date: Fri, 14 Jun 91 13:23:34 SET From: MSKALA%ESRIN.BITNET@vma.cc.cmu.edu Comment: CROSSNET mail via MAILER@CMUCCVMA Date: 14 June 1991, 13:22:51 SET From: Mike M. Skala ++39-6-94180-293 MSKALA at ESRIN To: space+@andrew.cmu.edu yamada@yscvax.ysc.go.jp ESA Press Release No.19; Paris, 14 June 1991 INVESTIGATION INTO OLYMPUS SATELLITE FAILURE STARTED The European Space Agency, ESA, has started an investigation into the origins of the loss, early on 29 May 1991, of orbit and attitude control of its Olympus Satellite. In parallel, ESA has succeeded in gaining additional evidence on the status of the spacecraft, thus improving the chances for recovering the mission in a few weeks. Olympus is an advanced telecommunications satellite featuring direct TV broadcasting, distance learning, various business networks and several other experimental payloads. As already reported, all services have been interrupted since the loss of control. The satellite rotates once every 90 seconds or so, and it is drifting eastwards at five dgrees a day. Since Olympus continues to send short streams of telemetry data to Earth, more information on its attitude and the status of its subsystems has been obtained in the meantime. The telemetry data indeicate in particular that, for the time being, the solar array is receiving rays from the Sun at a very oblique angle; in a few weeks this situation will improve, and it might then be possible to recharge the batteries and get commands into the satellite. Because of the present unfavorable orientation of the solar array, attempts to get commands into the satellite from NASA's high-power ground station at Robledo near Madrid (Spain) were unfortunately not successful. The Enquiry Board set up to investigate the cause of the failure met for the first time on 11 June 1991 under the chairmanship of Professor Massimo Trella, ESA Inspector General. It reviewed in detail the events immdeiately before and after the loss of control of the satellite. For reasons that are still not known and are currently the subject of a technical investigation, the satellite ceased to point at the Earth at 0321 hours GMT and went into Emergency Sun Acquisition Mode, which is an on-board automatic safety procedure that is activated whenever the satellite loses the Earth reference signal. In recovering from the emergency to the normal mode, commands were sent to the satellite that did not conform to standard procedures. It appears that modifications to those procedures had been introduced in an attempt to have the satellite back in normal mode by 0900 EST for the start of the broadcasting operations, but instead a sequence of events was initiated thet eventually led to loss of control. However, another contributing factor was the technical status of the satellite: one solar array had not been active since January, and had the solar generator been fully operational the spacecraft would most likely have recovered on its own. The team specially set up to lead activities to rescue the mission has started work, and has been analyzing all the available data from the satellite and the conditions onboard resulting from the abnormal attitude and power situation. At this time, it is believed that salvaging Olympus might be feasible. Detailed procedures are being agreed, and the actual recovery telecommands will be initiated in a few weeks, when solar illumination will have improved. ------------------------------ Date: 14 Jun 91 20:32:35 GMT From: cbmvax!ricci@uunet.uu.net (Mark Ricci - CATS) Subject: Re: Mars or bust! In article <1914@uqcspe.cs.uq.oz.au> rhys@cs.uq.oz.au writes: >> concerns among critics who are worried about the huge cost, put at $500 >> billion or more by some analysts. The report, issued after 10 months of >> study, did not mention a price tag. > >Numbers like this always make me laugh. They sound SO BIG!!! Let's say that >100 million Americans had to carry the cost in their tax (I don't know the >exact tax-paying population of America). We are talking $5000 each. OK, >maybe that's quite a lot to wear all at once. But we are talking over >20 years before the mission gets off the ground. Is $250 a year average too >much to ask? Heck, I pay more than that (the equivalent Australian amount) >each year on computer equipment and software alone (and I'm a VERY low-volume >buyer). My yearly bus pass costs around that as well. And not all of the >cost will be borne by the taxpayer if they get industry support, etc. > >Sheesh. Sheesh yourself, Rhys. You seem to forget that the US budget is bloated with far more than NASA's toys. The $250/year you cite would be added to the gouging that's already occurring. For that reason alone, it IS too much to ask. Mark -- ============================================================================= Mark Ricci - CATS | "I don't think so! Homey don't play dat." Commodore Applications and | Technical Support | - Homey the Clown ricci@cbmvax.commodore.com | In Living Color ============================================================================== ------------------------------ End of SPACE Digest V13 #745 *******************