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 ; Tue, 21 Nov 89 01:26:56 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 21 Nov 89 01:26:36 -0500 (EST) Subject: SPACE Digest V10 #266 SPACE Digest Volume 10 : Issue 266 Today's Topics: space news from Sept 25 AW&ST Re: Moon Ants Planetary data for space lift. Re: Mars Elevator Re: Planetary data for space lift. Re: Moon Colonies / Ant Tanks? NASA Headline News for 11/20/89 (Forwarded) ---------------------------------------------------------------------- Date: 19 Nov 89 21:48:41 GMT From: mnetor!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: space news from Sept 25 AW&ST Space Industries Inc may revive its Industrial Space Facility as an "out building" for the space station if budget cuts and engineering changes make the station less suitable for microgravity work. (In particular, changes aimed at support of lunar operations might do this.) Joe Allen, ex-astronaut and SII president, says that the biggest problem for the Moon/Mars initiative is not engineering or funding but the "ponderous laws of federal procurement". SDI starts development of a $400M sensor-demonstration satellite for launch in 1992. This will be the first space test of sensors suitable for use in an operational system. It will go up on an uprated Titan 2 with eight small solid strapons, being developed by Martin Marietta. The strapons will be variants of the Castor-4 used on the Delta. They will boost polar-orbit payload from 4200lbs to 7500lbs. MM is covering development costs; SDI is just buying the first launch. MM thinks the new Titan variant has commercial potential. Virginia attorney general tries to get Avtex Fibers shut down for polluting the Shenandoah river. Avtex is the sole source of rayon yarn used to make carbon-phenolic composites used in most US space and missile systems. Avtex has been in trouble on pollution rules before. Ford Aerospace picked to modernize Mission Control at Houston and to build a new control center for the space station. Ford built the original Mission Control in 1963. Large article, with color photos, on Mir expansion plans. Viktorenko and Serebrov report that Mir is in good shape, but does need some work; in particular, its batteries are getting old and need replacing. Mir's computer memory will be replaced by a new unit during September. Details of plans for add-on module installation etc. [now outdated because the launch of the D module has slipped]. The D service module will be followed by the T technological module, and later by the O optical Earth-resources module and an "ecological platform". Various small changes will be done as modules go up, including transfer of solar panels from module T to mountings on Kvant. Soviets report that Titov and Manarov re-adapted to a one-gee environment completely within two months of the end of their one-year Mir mission, and no aftereffects have been seen. Soviet doctors say that the extensive program of exercise and other countermeasures is the main factor in this. The cosmonauts were generally in better shape than others have been after five-month missions; in particular, bone changes were "not more evident". -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 20 Nov 89 22:48:02 GMT From: amdahl!drivax!macleod@sun.com (MacLeod) Subject: Re: Moon Ants In article <8911162346.AA08111@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: :I agree that there might be a problem with some of the kids (who never :volunteered to live in space) being discontented, as well as adults who decide :after a while that they want to return to Earth. However, I suspect that :most kids would become accustomed to the environment in which they had been :brought up, to the extent that they would probably be uneasy (at least at :first) walking around unprotected on the open surface of the earth. We already know that important physiological changes occur when a mature human lives in free-fall for a period of time. I would expect that children born on the Moon will grow up with lunar-adapted skeletons and musculature, and quite possibly would not be able to live on Earth in comfort, if at all. Then there is the possibility (inevitability - *sigh*) of discrimination between the two groups because they look so different to each other. Michael SLoan MacLeod (amdahl!drivax!macleod) ------------------------------ Date: 11/20/89 15:59:18 From: UDOC140%FRORS31.BITNET@CUNYVM.CUNY.EDU Comment: CROSSNET mail via SMTP@INTERBIT Return-Receipt-To: UDOC140@FRORS31.BITNET Subject: Planetary data for space lift. There has been a number of messages about the slow rotation of the Moon prohibiting any selenostationary cable. Indeed, it is the planet's rotation that makes the sky hook hold in the air under its own weight, but the only requirement is that the planet does rotate. This being the case for any known body, the rotation only gives a small bonus both on the cable's resistance and on the energy needed to transfer loads on stationary orbits. The other advantage is that the stationary orbit is lower when the rotation is high, so that the cable is shorter. But once again, the limiting factor is the cable's cross-section, not its length. Remember: Delta( Log(S) ) = p/s.r0.g0.(1 + x/2 -3/2.x^(1/3) ) where 'x'=w^2.r0.g0 is the ratio between centrifuge force and gravitational acceleration on the equator. Usually the corresponding reduction factor is negligible or only a few percent, so that the order of magnitude of the cable's dimention and weight is controlled by the r0.g0 factor, for a given material (for which p=density and s=maximal traction per square meter are constants). Here is the data for the inner planets (copied from a russian book, so this may be desinformation...): !Planet ! w : r0 : g0 : r1 : r0.g0 :reduction! ! name !E-6rad.s-1: E6 m :m.s-2 : E6 m :E6.m2.s-2: percent ! !-------------------------------------------------------------! !Venus ! 0.30 : 6.052 : 8.86 :1536.8 : 53.62 : 0.0 ! !Earth ! 72.72 : 6.371 : 9.81 : 42.2 : 62.45 : 22.6 ! !Mars ! 71.24 : 3.397 : 3.71 : 20.4 : 12.60 : 25. ! !Mercury! 1.24 : 2.44 : 3.68 : 242.4 : 8.98 : 0. ! !Moon ! 2.66 : 1.738 : 1.63 : 88.6 : 2.83 : 0.0 ! Moon's figures just give an order of magnitude, since Earth's attraction adds a small bonus: the two Lagrange points are at 58 E6.m for the inner one (288_557 furlongs) and at 65 E6.m for the outer one (35_519_125 fathoms - I love these old english units). The table shows our bad luck: of all the reachable planets, Earth is the one where the energy expense to reach synchroneous orbit is the largest, when rotation is not taken into account. When this correction is taken into account, the figure falls down to 48.4 E6.m2.s-2, some ten percent under Venus - which is definitely the unreachable planet. Mars' fast rotation together with its small gravity makes it almost as easy to reach as Mercury, and with a much shorter cable. For outer planets, the size and ground(?) acceleration clearly prohibits any cable for the time being. (Exept of course for Pluto - but who wants to go there anyway?) The data for their larger satellites might be nevertheless useful, but we can wait a while before we reach them and use them industrially. The cable's construction consists basically in launching a synchroneous satellite plant, a big spider wich will spin the cable both up and down so as to remain in equilibrium. The gravitation field tends to align both cables toward the planet's center, whereas the cable's progression tends to tilt it due to gyroscopic effect. For a proper progression, both effects cancel out (and the cable has a constant tilt). Once the cable reaches the ground, one simply has to anchor it, then add some weight at the other end so as to put it under tension (otherwise the cable would be unable to lift anything: adding a payload at the bottom would merely pull the satellite down...). The plant need not be a synchroneous one, of course, thought it simplifies the matter. As Michel van Roozendaal pointed out (13 nov. 89), the cable itself can be used to control the station's final altitude: if a load is thrown downward before the cable is anchored, the station will be pulled upward, and mutatis mutandis an upward load thrown into space will lower the station. As soon as the cable is anchored, up and down traffic change the planet's momentum and not the satellite's, so that the corresponding energy is free and the effect negligible. This can be helpful for Mars: as Paul F. Dietz said in this forum (17 nov. 89), Phobos can be pulled in higher orbit using a tether that throws part of its mass on Mars. Of course, this has to be done before we send anybody down there. (Pebbles in the sky? Who said that?) Phobos is not that large (a couple of kilometer across), so that digging out part of it is not much of a problem once you get there. *BUT* this only give a synchroneous orbit: how can it be turned into a Mars-stationary one (that is: bring Phobos' orbit into Mars' equator)? This is also useful for the Moon: it would be useless to build a plant in sel.-station. orbit, since the target Lagrange points are unstable: the plant would tend to drift away, and correcting the trajectory of a thousand-kilometer long satellite might be tricky. It would probably be easier to assemble the cable on a lower stable orbit, then give the station a final pull up while bringing down some weight and the last part of the cable. Et voil'a. Bertrand MICHELET uDoc140 at FrOrs31 (BitNet) ------------------------------ Date: Mon, 20 Nov 89 18:56:50 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Mars Elevator >From: sei!firth@pt.cs.cmu.edu (Robert Firth) >Subject: Re: Mars space elevator >In article <8911170010.AA08134@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >>This problem was discussed in Fountains >>of Paradise by Arthur C. Clarke. The proposed solution was to set up a >>carefully-controlled vibration in the elevator, which would cause it to >>move out of the way as Phobos passed by. >Um... wouldn't it be a lot simpler to move Phobos? Several people have pointed out that it would be an undertaking way beyond current technology to get Phobos beyond synchronous orbit or crash it into Mars. While this is true, there is an alternative which is "not quite as impossible". The Martian day is about 24.62 hours. Phobos orbits Mars in about 7.65 hours. If this period could be increased to around 8 hours, so that it was exactly equal to 1/3 of the period of a synchronous orbit, it seems to me that it could be set up to always pass over the equator at certain fixed points. You could then pick a spot that it never passes over, and build the elevator there. Of course, you might have to periodically adjust Phobos' orbit to maintain this relationship, which would be a nuisance. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 21 Nov 89 02:19:45 GMT From: jarvis.csri.toronto.edu!me!helios.physics.utoronto.ca!physics.utoronto.ca!neufeld@rutgers.edu (Christopher Neufeld) Subject: Re: Planetary data for space lift. In article UDOC140@FRORS31.BITNET writes: > >This is also useful for the Moon: it would be useless to build a >plant in sel.-station. orbit, since the target Lagrange points are >unstable: the plant would tend to drift away, and correcting the >trajectory of a thousand-kilometer long satellite might be tricky. > > Bertrand MICHELET > uDoc140 at FrOrs31 (BitNet) Please, somebody correct me if I'm wrong. The L1 and L2 points are 2/3 stable points, so that a mass which drifts in the plane perpendicular to the line connecting the two masses tends to drift back to the L1/L2 point. The unstable direction is radial. If it falls slightly toward the earth, it will keep falling that way. The converse is also true. Since the tether would be anchored at the moon, and held under tension by the ballast weight, it seems to me that this situation should still be dynamically stable. Of course, I'm ignoring quadrupole mass effects for the earth and the moon, and the sun's gravitational force. Still, it should be fine without active maneuvering. -- Christopher Neufeld....Just a graduate student | "Space probe may be cneufeld@pro-generic.cts.com | Doomsday machine!" neufeld@helios.physics.utoronto.ca | -Toronto Star article "Don't edit reality for the sake of simplicity" | on Galileo 19/11/89 ------------------------------ Date: 18 Nov 89 01:18:26 GMT From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!leonard@uunet.uu.net (Leonard Erickson) Subject: Re: Moon Colonies / Ant Tanks? dmocsny@uceng.UC.EDU (daniel mocsny) writes: >What does this have to do with space? Industries and economies that >are not spectacularly profitable in an environment with more >advantages than anyplace else in the solar system will not work >elsewhere. The only way to overcome the expense of an inherently >hostile environment is to increase the productive ability of each >individual. This translates ultimately into giving the individuals >more Information Power. Of course we will do this anyway whether >we go to space or not. But if you want to get something viable >going upstairs, that is the place to start. You are assuming that space is a hostile environment *in general*. For many industrial activities, space or the moon have *advantages*. The disadvantages have to do with the need to give workeres more protection from the environment. Semi-silly example. A steel mill in space can obtain high temperatures more easily and *maintian* them even more easily. Vacuum is an advantage here. Gravity may or may not be desired. Once you get to the point where you are working on the billets then the situation is more nuetral, or possibly even slightly negative (lubrication is harder in space, cooling is a *lot* harder). -- Leonard Erickson ...!tektronix!reed!percival!bucket!leonard CIS: [70465,203] "I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters." -- Solomon Short ------------------------------ Date: 20 Nov 89 19:23:07 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 11/20/89 (Forwarded) ----------------------------------------------------------------- Monday, November 20, 1989 Audio: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Monday, November 20.... Project officials at Goddard Space Flight Center report that the Cosmic Background Explorer satellite is operating well following its launch into near polar orbit last Saturday. The COBE spacecraft was placed into orbit by a Delta rocket. The delta rose off the pad ten minutes into the half-hour launch window after high winds aloft finally abated enough to allow the lift-off. COBE was placed into a 559-mile circular orbit. As COBE scientists prepare for their one-year search for remnants of the big bang some 15 billion years ago....astronomers at Palomar Observatory report that they have located a quasar 14 billion light years from earth making it the most distant and oldest object ever discovered. Workers continue their pre-launch pad operations at Kennedy Space Center aiming for a Wednesday lift-off of the space shuttle. Discovery's five-member crew arrived at KSC Sunday afternoon. Pad workers were running behind schedule over the weekend completing work on the the right hand Solid Rocket Booster Following replacement of an Electronic Controller Unit. Launch Director Robert Sieck told United Press International it would be "a very tight fit in terms of being finished in time" for Wednesday evening's scheduled launch. Discovery's payload bay doors have been secured and today pad personnel are closing out the aft compartment of the orbiter. The classified Department of Defense mission will be launched sometime after 6:30 P.M., Eastern time, Wednesday. Last Friday, NASA Administrator Richard Truly provided members of the National Space Council with the results of a 90-day study aimed at establishing a manned base on the moon and a manned mission to Mars. The report came about as the result of President Bush's space initiative earlier this year. The paper spelled out issues and discussed special technology required for the two proposed programs. The White House has released an unclassified version of a revised national space policy. The document, approved by the President earlier this month, contains strong support for human exploration of the solar system and for commercial space ventures. * * * ----------------------------------------------------------------- Here's the broadcast schedule for public affairs activities on NASA Select TV. All times are Eastern. Wednesday, November 22...... 5:30 P.M. Coverage begins of the STS-32 launch only of the space shuttle orbiter Discovery. The mission is classified. This note: NASA Update will not be transmitted this Thursday because of the Thanksgiving holiday. All events and times are subject to change without notice. ----------------------------------------------------------------- These reports are filed daily, Monday through Friday, at 12 noon, Eastern time. ----------------------------------------------------------------- A service of the Internal Communications Branch (LPC), NASA Headquarters, Washington, D.C. ------------------------------ End of SPACE Digest V10 #266 *******************