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 ; Sun, 31 Mar 91 01:39:15 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 31 Mar 91 01:39:09 -0500 (EST) Subject: SPACE Digest V13 #330 SPACE Digest Volume 13 : Issue 330 Today's Topics: MAJOR GEOMAGNETIC STORM UPDATE #1 - 27 MARCH - STORM ENDED Re: Linear launchers on Earth RE: EM Launchers and G loads Shuttle Velocity Commercial Space news (4 of 12) Re: "Follies" Commercial Space news (12 of 12) 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: Wed, 27 Mar 91 16:45:31 MST From: oler%HG.ULeth.CA@BITNET.CC.CMU.EDU (CARY OLER) Subject: MAJOR GEOMAGNETIC STORM UPDATE #1 - 27 MARCH - STORM ENDED X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ GEOMAGNETIC STORM UPDATE /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ 23:30 UT, 27 March ------------- STORM UPDATE INFORMATION: The update scheduled for 06:00 UT was not posted due to local computer problems. We apologize for the loss of that update. The geomagnetic and auroral storm has ENDED. A shock from the recent major flaring has not yet been observed, and the probability for observing another shock is falling as time passes. Presently, an increase in geomagnetic activity is not expected. A return to more normal conditions will continue. HF and VHF conditions are quickly returning to normal over middle and low latitudes. DX is now possible, following the strong degradations which occurred earlier this week. Conditions, particularly over the more northerly latitudes, will continue to be somewhat unstable, although significant improvements are expected. High latitudes and polar latitudes will continue to experience some degradation in signal quality due to enduring proton activity. However, the strong PCA event is pretty well over now. Only very slight absorption is being measured (less than 0.5 dB in the night-sectors). Thanks to all of you who sent in reports during this major event. A summary of this event will be compiled and posted for general viewing over the next few weeks. The following alerts have been CANCELLED: - MAJOR GEOMAGNETIC STORM ALERT - GEOMAGNETICALLY INDUCED CURRENT (GIC) ALERT - LOW LATITUDE AURORAL ACTIVITY ALERT The following alerts remain IN PROGRESS: - SATELLITE PROTON EVENT ALERT - POLAR CAP ABSORPTION EVENT ALERT - POLAR AND HIGH LATITUDE RADIO SIGNAL BLACKOUT ALERT The following warnings are IN PROGRESS: - POTENTIAL MAJOR SOLAR FLARE WARNING - POTENTIAL PROTON FLARE WARNING /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ ------------------------------ Date: Wed, 27 Mar 91 22:12:12 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Linear launchers on Earth >From: henry@zoo.toronto.edu (Henry Spencer) >Subject: Re: EM Launchers and G loads >Date: 27 Mar 91 17:44:31 GMT >Organization: U of Toronto Zoology >In article RANCK@VTVM1.CC.VT.EDU ("Wm. L. Ranck") writes: >>...something running along the desert and then gradually curved up the side >>of a mountain... >Building that last curve will be a civil engineering project to end all >civil engineering projects -- a large mass moving at 7-8 km/s tries >very hard to keep on moving in a straight line. Assume a bend radius >of 10km, which is pretty generous, and the side force at 7km/s is a >mere 500G. Wasn't this supposed to be a low-acceleration device... :-) It would be a very *big* project, but the magnitude of the force shouldn't be all that unmanageable. (I agree it wouldn't be worth it.) >What you want, actually, is to build a rather shorter catapult along >a long, high mountain ridge sloping up to the east. Then you can make it >straight and still shoot into relatively thin air. You don't actually >need the upward angle -- the Earth's curvature will take it out from >under your payload quickly enough -- but getting out of the atmosphere >is important. >"[Some people] positively *wish* to | Henry Spencer @ U of Toronto Zoology >believe ill of the modern world."-R.Peto| henry@zoo.toronto.edu utzoo!henry OK, here's a new idea for a linear launcher that I bet isn't even among Eugene's 9999 (that have already been thought of): First, build the linear launcher of your choice, but make it completely level. Second, get several hundred million tons of steel, and build an artificial mountain along the trajectory of the launcher. The slope of the side facing the launcher should have a slope of something less than 45 degrees (an adjustable slope would be nice), and the outer 10 or 20 meters should be made of tempered spring steel. Now, when you fire your launcher, the projectile shoots out of the muzzle, and -BLAMMO!- ricochets off the slope of the steel mountain, flying off into space at a nice, steep, atmosphere-avoiding trajectory. Of course, this won't do anything to reduce G-loading (the forces will be rather high at the instant of impact), and you will probably have to repair or replace the mountain surface periodically, but think of the simplification of the engineering! :-) :-) :-) Another problem for linear launchers in general: I don't have the numbers handy, but I believe the shock wave of the projectile passing through the atmosphere would generally be great enough to kill everything for several miles around (and it could be heard for hundreds of miles). Fortunately, there are regions in the Andes that are little more than bare soil for hundreds of miles. So pick out whatever western South American country we have the least bad relations with at the moment, and start negotiating. :-) John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Wed, 27 Mar 91 11:06:37 EST From: "Wm. L. Ranck" Subject: RE: EM Launchers and G loads Hello folks, I have been reading the Space Digest archives for a while and noticed an ongoing discussion of the problems/potentials of EM or 'rail gun' launchers. Since I first saw some reports on MIT experiments with this technology I have always thought it would be a good method for launching space vehicles. Now, my question is this. Why does everyone assume that you want maximum acceleration from the system in the shortest possible distance. I can see that it make the system cheaper to build and the energy efficiency is probably better; but why not build a long rail system that accelerates the payload at 2 or 3G over many miles. Imagine something running along the desert and then gradually curved up the side of a mountain. At the top end you still need a booster of some sort to circularize your orbit, but it could be a heck of a lot smaller than the monsters we launch now. Is there some obvious problem with this that I'm missing? Is it just tunnel vision that makes people think of maximum acceleration from an EM launcher? Of course for smaller hardened payloads a higher rate of acceleration could be provided by the very same launcher. This is probably a novice FAQ, but I couldn't find anything in the archives. Bill Ranck ------------------------------ Date: Wed, 27 Mar 91 15:12:26 CST From: JD Subject: Shuttle Velocity X-Acknowledge-To: I was in an discussion with a friend of mine and we got talking about the Shuttle and we were discussing the speeds that the shuttle must achieve. And I am one for trivia, so I remembered I fact I thought I had heard--that when the shuttle clears the tower it is going over 100 mph. He didn't believe me and said that would be to fast and it would create to many G's for human to take. Could someone out there please back me up on this or correct me. And if someone knows could you please send me some numbers, such as velocity when clear of the tower and G-forces acting on the shuttle. I know this is trivial but we are both interested to find out if this is correct. Thanks for the help!!! JD (S105646@UMRVMA) |************************************ University of Missouri-Rolla |************************************ Computer Science, Freshmen |************************************ Nick Name - ??? John Doe ??? |************************************ -- Surgeon General's Warning -- |************************************ -- JD is known to be a -- | "My God, it's full of stars" -- very punny person!!!! -- | --2001: A Space Odyssey ------------------------------ Date: 26 Mar 91 05:22:30 GMT From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@ucsd.edu (Wales Larrison) Subject: Commercial Space news (4 of 12) CHANGE OF COURSE FOR ADVANCED MOBILE SATELLITE? There is much discussion in the communications satellite field of a change in an important joint NASA/commercial program to demonstrate new technology for mobile communications systems. The AMSC satellite, which is being built by American Mobile Satellite Co., is a joint venture by a consortium of U.S. communications firms. NASA provided funding for the development of critical technologies for this system, and has offered to support the launch and to fund a demonstration program of this system, as well as negotiating a joint usage arrangement with Canada. The primary change in the program is in the form of the NASA support for the launch of the satellite. Back in 1985, NASA had offered to provide a free Shuttle launch for the first mobile satellite a system. Under a Joint Endeavor Agreement (the primary legal structure available at that time for industry/NASA cooperation), NASA would receive in return the use of 15% of the satellite services for at least 2 years. In 1986, Presidential policy removed this type of satellite from the Shuttle, and the offer changed to an offer of a Delta-class ELV launch, up to $57.5 M. In 1988, AMSC was formed as a a consortium of 8 U.S. communications companies, and they have duly requested and have been granted a FCC license to build, launch and operate a mobile service satellite for the U.S. and Puerto Rico. However, the decision to give AMSC the only U.S. license for mobile satellites service was just overturned by a federal appeals court. This could delay the start of the venture by 2 to 5 years. The panel reversed the FCC dismissal of some competitor's applications as it found no justification for requiring a $5M deposit from each applicant to force the formation of a consortium over selecting the best single application. This decision will be reivewd by the full appeals court, with possibly eventual appeal to the Supreme Court, or force an unraveling of the consortium. Under the new (1991) Presidential policy on commercial space activities, the original barter deal (launch services for satellite services) is being changed to where NASA acts as an anchor tenant, making up-front progress payments, and purchasing a larger percentage of satellite use. Working from the original FCC and NASA decisions, AMSC has shelled out $100 M to Hughes to build the satellite. The satellite weight has grown, and an Atlas or Ariane launch is now required. Under the original barter deal, Ariane launches could not be considered, since NASA would have to book the launch and Federal law eliminates consideration of the Ariane under a "buy American" clause. Since the new approach has AMSC negotiating and booking the satellite launch, Ariane launch may be considered (although some remaining legal questions have to be resolved on this). Once launched, NASA would manage a 2-4 year demonstration program to introduce mobile communications services to federal, state, and local government agencies. Already, 10 federal agencies have agreed to cover the ground segment costs of using the AMSC satellite. It should also be noted that NASA has already negotiated a joint agreement with the Canadian Communications Department. It would allow a similar Canadian system to be used by the U.S. government and the NASA portion of the AMSC system to be used by Canada, if either system was not available. The Canadian government recently awarded $125 M for future mobile satellite services to Telesat Mobile Inc in Ottawa, AMSC's counterpart. [NASA has been the primary driver for developing and -- Wales Larrison Internet: Wales.Larrison@ofa123.fidonet.org Compuserve: >internet:Wales.Larrison@ofa123.fidonet.org -------------------------------------------------------------------------- ------------------------------ Date: 27 Mar 91 10:17:13 GMT From: mcsun!ukc!axion!uzi-9mm.fulcrum.bt.co.uk!beta.its.bt.co.uk!tjo@uunet.uu.net (Tim Oldham) Subject: Re: "Follies" In article <1991Mar20.221452.14658@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >Plymouth Rock was financed by borrowing on a large >scale -- the colony took nearly twenty years to get out of debt -- >because the colonists' life savings weren't enough. My mortgage is for 25 years. Doesn't sound so bad to me. Tim. -- Tim Oldham, BT Applied Systems. tjo@its.bt.co.uk or ...uunet!ukc!its!tjo US Tourist: ``Say, is this college pre-war?'' Porter: ``Madam, this college is Pre-America.'' ------------------------------ Date: 26 Mar 91 05:31:12 GMT From: sdd.hp.com!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@ucsd.edu (Wales Larrison) Subject: Commercial Space news (12 of 12) firms who then can get the financing to make the needed investments. Another way is to directly challenge Arianespace and Japan's Rocket Systems Corp and set up a consortium of US transportation companies as examined by the CBO. However, I would also expand this consortium to also include the shuttle and manned missions under its purview - organizing it approximately as was done with Comsat Corp. Since about 90% of the market demand is governmental, the consortium (SpaceTran Corp?) would act as the clearinghouse for government launch services contracts (including manned missions), and within the consortium "divisions" responsible for Titan, Atlas, Shuttle, or Delta launches could compete for the launch contracts. This single point of contact would be the focus for international marketing of U.S. launch services, including insurance and financing. It would also provide an umbrella under which technology development could take place for the use of all U.S. launch providers, and by spreading the risk over several firms with a more stable market in total, would make obtaining commercial financing more feasible. This has the problems of creating a centralized launch system organization, but since over 90% of the launches are governmental we already have such an organization - just not named as such. The ultimate goal of this organization would be to eventually become totally commercial and answer only to shareholders and the market (as Comsat has become). Comsat did not prevent the commercial- ization of communications satellite technology, and I think that a "SpaceTrans Corp" could also provide an equivalent role to encourage U.S. space transportation technology. We do need to do something to encourage and promote the U.S. space transportation industry. These suggestions are just a few of the many ideas I've seen over the past several year. But as usual, I expect the government will do nothing - but do nothing with a lot of flames and shouting.] [As a last note, does anyone have suggestions on how this informal set of news updates can be improved? I'm looking for feedback on preferences and types of information people are looking for. Send via e-mail your opinions to the address shown below. Hope you find this amusing and interesting - I've been having a blast putting it together. ] ----------------------------------------------------------------- Wales Larrison Space Technology Investor tempora mutantur, nos et mutamur in illus s -- Wales Larrison Internet: Wales.Larrison@ofa123.fidonet.org Compuserve: >internet:Wales.Larrison@ofa123.fidonet.org -------------------------------------------------------------------------- ------------------------------ End of SPACE Digest V13 #330 *******************