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 ; Mon, 6 May 91 02:17:02 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 6 May 91 02:16:57 -0400 (EDT) Subject: SPACE Digest V13 #492 SPACE Digest Volume 13 : Issue 492 Today's Topics: Jonathan's Space Report, May 3 Re: Gas Guns and Tethers Re: SPACE Digest V13 #470 Re: Galileo Update On CNN atmosphere probe question Re: SPACE Digest V13 #475 Re: Terraforming Venus Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster) Re: slight problems with HLV's in general, Saturn or not... Terraforming Venus? Re: Saturn V vs. ALS 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: 3 May 91 19:59:23 GMT From: swrinde!elroy.jpl.nasa.gov!freedom!xanth!mcdowell@ucsd.edu (Jonathan McDowell) Subject: Jonathan's Space Report, May 3 Jonathan's Space Report May 3 1991 (no.73) ---------------------------------------------------- Discovery was launched on mission STS-39 at 1133.14 UT on Apr 28. The IBSS-SPAS satellite was deployed on May 1 at 0817 and retrieved at 2225 on May 2. The CRO-C subsatellite was deployed on May 2 at 0128; the CRO-B subsatellite was deployed on May 2 at 1803; the CRO-A subsatellite was deployed on May 3 at 1210. Landing is scheduled for May 6. Viktor Afanas'ev and Musa Manarov continue in orbit aboard the Mir/Kvant/Kvant-2/Kristall/Soyuz TM-11/Progress M-7 complex. Launch of Soyuz TM-12 is due for May 18, with the replacement long stay crew of Anatoliy Artesbarskiy and Sergey Krikalyov. Soyuz TM-12 will also carry as a passenger the British Project Juno cosmonaut Helen Sharman, who will return with Afanas'ev and Manarov in Soyuz TM-11. Kosmos-2142, a navigation satellite, was launched by Kosmos R-14 from Plesetsk on Apr 16 into a 1000 km orbit. The fourth Meteor-3 weather satellite was launched by Tsiklon from Plesetsk on Apr 24 into a 1200 km orbit. ___________________________________ |Current STS status: | |Orbiters | | | |OV-102 Columbia LC39B | |OV-103 Discovery Earth orbit | |OV-104 Atlantis OPF Bay 2 | |OV-105 Endeavour Palmdale | | | |ML/ET/SRB stacks | | | |ML3/STS-40/ET/OV-102 LC39B | ----------------------------------- 20 years ago: 5 May 1971. DSP F2 was launched by Titan 3C from Cape Kennedy. It was the first successful craft in the DSP early warning satellite system, which watches for missile launches from stationary orbit. DSP F2 was stationed over the Indian Ocean. 30 years ago: 5 May 1961. The Mercury spaceship "Freedom Seven", with astronaut Alan B. Shepard aboard, was launched on the suborbital MR-3 mission by a Redstone booster. Shepard became the first U.S. citizen to enter space; the flight lasted 15 minutes. (c) 1991 Jonathan McDowell. Information in this report is obtained from public sources and does not reflect the official views of NASA. .-----------------------------------------------------------------------------. | Jonathan McDowell | phone : (205)544-7724 | | Space Science Lab ES65 | uucp: | | NASA Marshall Space Flight Center | bitnet : | | Huntsville AL 35812 | inter : mcdowell@xanth.msfc.nasa.gov | | USA | span : ssl::mcdowell | '-----------------------------------------------------------------------------' ------------------------------ Date: 3 May 91 19:23:29 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!ox.com!fmsrl7!wreck@ucbvax.Berkeley.EDU (Ron Carter) Subject: Re: Gas Guns and Tethers In article waltdnes%w-dnes@torag.uucp writes: [regarding capturing sub-orbital payloads with a tether] >Theoretical problem 1) The centre-of-mass of the combined structure has >instantaneously dropped closer to the earth's surface without the orbital >velocity increasing. The result should be a lower orbit. This is not a problem. It requires only: a.) that the decrease in the size of the orbit be managable, or b.) the opposite end of the orbit be higher to compensate. >Theoretical problem 2) Remember my "Summary:" line about no boostrapping? >As the shuttle climbs the tether, the space-station+tether descend a bit. >Since we're dealing with a closed system, the centre-of-mass must remain >in the same orbit. Yes, so? Is an absolutely constant orbit a requirement? For what? >Practical problem 1) Conservation of angular momentum... Unless the >shuttle matches velocity *VERY* closely with the station, the two bodies >will be spinning around each other at some horrendeous rpm's by the time >the shuttle has climbed all the way up the tether. You are ignoring tidal effects on the tether, which tend to hold it along the primary's radius. After a payload capture, the tether would swing back and forth relative to the radius like a pendulum. By proper control of the tether reel, these swings can be damped. > The theoretical problems are where many "perpetual-motion machines" >trip over reality. It takes X joules of work to lift a specific payload >to a specific orbit. If you'd take a detailed look at the energy and angular momentum transfers, you'd realize that tethers don't offer a free lunch, or a free launch. What they give you is checking and credit, letting you loan or transfer energy and angular momentum w/o using rockets. ------------------------------ Date: 3 May 91 00:22:03 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!uakari.primate.wisc.edu!samsung!umich!umeecs!msi.umn.edu!cs.umn.edu!kksys!wd0gol!newave!john@ucbvax.Berkeley.EDU (John A. Weeks III) Subject: Re: SPACE Digest V13 #470 In article 18084TM@MSU.EDU (Tommy Mac) writes: > The computer that was used on the original Apollo Landings had only 64K of > core memory. > It's teeny sure, but they did it with tubes back then. To give you an idea > how that translates into lbs, a 40 BIT register that we have in a showcase > here weighs about 20lbs. That means that 64K of tube-memory would translate > to, say 40000 lbs? That can't be right! It must be really heavy tho. > That;s not even talking about the coooling system they needed. > (That 40 bit job was about 2 cubic feet) Think about the space 2 cubic feet would have to scale up to in order to become 64K. The 64K is main memory, where as a register would be part of the CPU. The Apollo CPU was solid state. The memory was probably magnetic core. No tubes in either, but I bet the CPU still generated a bit of heat. The magnetic core memory is surprisingly small, except when compared to IC chip memory. -john- -- ============================================================================= John A. Weeks III (612) 942-6969 john@newave.mn.org NeWave Communications ...uunet!tcnet!wd0gol!newave!john ------------------------------ Date: 4 May 91 07:51:16 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Galileo Update On CNN atmosphere probe question In article <1991May3.203721.6889@cbfsb.att.com> wa2ise@cbnewsb.cb.att.com (robert.f.casey) writes: > >I saw part of this news report, too. There was mention that if they can't >get the antenna fixed, there will be no nice pictures. But they can still >do the atmosphere probe. Are there cameras on this probe (didn't think so)? >Data rate on the probe must be fairly low, then, if the antenna problem >won't get in the way. Will NASA "hear" the atmosphere probe directly from >Jupiter without being relayed thru Galileo? The Galileo atmospheric probe has no camera. All its data is transmitted by a low power, omni-directional antenna. It is low power since it must run off of the probe's bateries and omni-directional, since a directional antenna could not keep an keep pointing in a constant direction, while hanging from a parachute in possible gale-force winds. As a result the probe has a very low data rate, even to the nearby orbiter. From Earth the probe's signal would inaubable, so the orbiter must be there to relay the signal. The good news is that, given the short transmission time and low data rate, the orbiter can transmit via its low gain antenna and/or store the data for later transmission. Frank Crary UC Berkeley ------------------------------ Date: 1 May 91 22:38:53 GMT From: wuarchive!rex!rouge!dlbres10@decwrl.dec.com (Fraering Philip) Subject: Re: SPACE Digest V13 #475 In article <9105011747.AA01962@ucbvax.Berkeley.EDU> space-request+@ANDREW.CMU.EDU writes: >Sure dropping Jupiter for a 'few measly asteroids' would seem to be a waste. >But dropping Jupiter for the most abundant, accessible resources and plantetary >science specimens in the Solar System is a FANTASTIC idea. >Remember that, unlike the Planets, we can (eventually) study every gram of the >Asteroids, given the time and determinantion. We will never study the interior >of any of Jupiter's moons, let alone Jupiter. >This not only means the Asteroids would make better scientific specimens, but >also means we can recover all the heavy metals (i.e. gold, iron, lead, copper) >that are forever hidden at the center of the other planets. >And finding those heavy metals could be the incentive that private industry >needs to get their butts busy building a space infrastructure. >You would like to see a space infrasturcture wouldn't you? >Tommy Mac >Acknowledge-To: <18084TM@MSU> Yes, but at present Galileo is a very lousy asteroid probe. You aren't going to get much info from a bunch of 100 or so meters/sec flybys from a great distance. Something a lot smaller than Galileo, with instruments more appropriate to the task, could for less money than the replacement to Galileo to Jupiter give us a lot better asteroid data. Besides, for economic development, you'd want to look at the near-earth asteroids. Am I the only one here who understands that you won't get optimal data using a planetary orbiter to look at asteroids? -- Phil Fraering dlbres10@pc.usl.edu Joke going around: "How many country music singers does it take to change a light bulb? Four. One to change the bulb, and three to sing about the old one." ------------------------------ Date: 2 May 91 00:42:25 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!sdd.hp.com!wuarchive!rex!rouge!dlbres10@ucbvax.Berkeley.EDU (Fraering Philip) Subject: Re: Terraforming Venus In article <74253@eerie.acsu.Buffalo.EDU> v096my2q@ubvmsc.cc.buffalo.edu (Mark A Wieczorek) writes: >Also when people talk about bombarding either mars or venus with >comets. Where are they going to come from and how are they going to >get here? >Is their any evidence that their actually is an oort cloud, or is this >just a nice hypothesis? >Mark Wieczorek Yes, there actually is an Oort Cloud, and many of the comets were there before they entered the inner solar system. However, over the lifetime of the solar system, the Oort Cloud doesn't last very long, so there is also a closer reservoir of comets called the Kuiper Belt, past Neptune and Pluto, I don't really have the numbers handy. All the scales I've seen the distances displayed on have been logarithmic in nature; just past Neptune could be an orbit twice as large, as far as some people are concerned. Neither of these places are very convienent in terms of energy, but neither is terraforming Venus to begin with. Terraforming the moons of Jupiter would probably be easier :-). -- Phil Fraering dlbres10@pc.usl.edu Joke going around: "How many country music singers does it take to change a light bulb? Four. One to change the bulb, and three to sing about the old one." ------------------------------ Date: 5 May 91 02:46:32 GMT From: skipper!shafer@ames.arc.nasa.gov (Mary Shafer) Subject: Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster) In article <1991May4.023935.10779@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1991May3.161528.29165@en.ecn.purdue.edu> irvine@en.ecn.purdue.edu (/dev/null) writes: >>No, life DOES NOT have a value that can be estimated. The LEGAL >>COSTS of a trial does not equate to a human life. >Life may not have a value that can be estimated, in some theoretical sense, >but for practical planning one *must* assign it some specific value. There >is *NO LIMIT* to how much you can spend making the hardware a little bit >safer. If you want to get anything done, sooner or later you have to say >"enough". Whether you like it or not, when you say that, you have set the >value you put on life. To provide a more explicit example of what Henry says, in the early 70s Caltrans (California Department of Transportation) set the value of one life at $100,000. The cost/benefit analysis had to reflect this value: if a recommended action cost more than $100,000 times the lives that would be saved in the first n years, the action would not be taken. That's why there are a lot of 4-way stops near schools and few signals. >"For perfect safety... sit on a fence and watch the birds." --Wilbur Wright To quote something I said last year, "Perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA "Turn to kill, not to engage." CDR Willie Driscoll -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA "Turn to kill, not to engage." CDR Willie Driscoll ------------------------------ Date: 2 May 91 18:08:41 GMT From: hela!aws@uunet.uu.net (Allen W. Sherzer) Subject: Re: slight problems with HLV's in general, Saturn or not... In article <1991May2.020418.13913@world.std.com> unicorn@world.std.com (unicorn) writes: >AWST reported that one of the reason that the Russian heavy lift vehicle >has not flow again is that there is no payload for it. Agreed. Outside of SEI there is no current need for a 250K to LEO launcher. However, if a cheap 100K pound to LEO launcher came up (like HL Delta or Titan V) then I think we would see payloads. Space at GEO is getting tight and large payloads means larger satellites which make better use of the space available. >I think that the >US should com up with a list of prospective payloads for the first few >years of the vehicles life. In that case there are no payloads. Nobody in their right mind is going to spend the money to develop the payloads with no way to launch them. If Von Braun had that attitude there would have been no Apollo 11. The work on the F-1 engine began long before a need for it (apollo) was identified. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | Allen's tactics are too tricky to deal with | | aws@iti.org | -- Harel Barzilai | +---------------------------------------------------------------------------+ ------------------------------ Date: 2 May 91 16:48:43 GMT From: cadence!jonmon@uunet.uu.net (Jon Monsarrat x6227) Subject: Terraforming Venus? > dlbres10@pc.usl.edu (Philip Fraering) writes: > > Terraforming the moons of Jupiter would probably be easier :-). Wait, do Jupiter's moons (like Ganymede) have enough gravity to support an atmosphere even if supplied with impacted comets? Thanks to any responders! -Jon Monsarrat jonmon@cadence.com ------------------------------ Date: 28 Apr 91 23:59:52 GMT From: unisoft!fai!sequent!crg5!szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: Saturn V vs. ALS In article rjc@cstr.ed.ac.uk (Richard Caley) writes: >Besides, there is nothing sacred about one payload per rocket. Sharing works only where there is a common destiation orbit and time of deployment. There are many orbits of interest -- GEO, low polar, SSO, Molniya, equatorial, 28 degree, 60 degree, 5 Lagrange points, various deep space trajectories -- and many possible planes within some of those orbits. Unless the two spacecraft just so happen to share a common destination _and_ a common time of deployment, and just so happen to fit together in the payload shroud, sharing a launcher can be a severe handicap. Furthermore, sharing requires specialized payload interfaces which decrease the payload well below the specified maximum launch mass, and increase price due to the customized hardware. At this point, sharing probably only makes sense for some GEO-bound satellites and microsatellites systems with multiple spacecraft per plane (eg Iridium). -- Nick Szabo szabo@sequent.com "Living below your means allows you to live better than living above your means." -- Dave Boyd The above opinions are my own and not related to those of any organization I may be affiliated with. ------------------------------ End of SPACE Digest V13 #492 *******************