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 ; Thu, 11 Apr 91 01:28:59 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 11 Apr 91 01:28:51 -0400 (EDT) Subject: SPACE Digest V13 #390 SPACE Digest Volume 13 : Issue 390 Today's Topics: shuttle radiator experiment Re: space news from March 4 AW&ST Re: comsat cancellations and lawsuits Re: Space Stations, Money, Startrek Re: SPACE Digest V13 #364 Re: back-up crews Re: Advancing Launch Technology Re: Nuclear Rockets Re: SPACE Digest V13 #378 Re: SPACE Digest V13 #364 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, 10 Apr 91 09:56:33 EDT From: Alan B. Owens Subject: shuttle radiator experiment *** Reply to append in SPACE USENET of 13:31:37 on 91/04/10 writes: >I hear on CNN that there was a space station radiator experiment on board. >They never say what kind of radiator, yet it involved fluid. Does anybody >knw what type of radiator the experiment was testing? Since space >radiators are what the main thrust of my thesis' desin prject, any >information would be helpful. It's the Space Station Heatpipe Advanced Radiator Element (SHARE II). Alan B. Owens Building 182, Room 3M106 Staff Programmer 800 N. Frederick Avenue IBM Corporation Gaithersburg, Md 20879-3395 owensa@wmavm7.vnet.ibm.com 301-240-7191 ------------------------------ Date: Wed, 10 Apr 91 14:08:40 -0400 From: "Allen W. Sherzer" Subject: Re: space news from March 4 AW&ST Newsgroups: sci.space,sci.space.shuttle Cc: In article <1991Apr10.053135.3470@zoo.toronto.edu> Henry Spencer writes: >DoT issues the first launch operator's license, to General Dynamics... >[It is not clear what this means, although the suggestion is clearly that >GD won't have to go through as much paperwork for each launch. Yep. They can pretty much launch Atlas at will as far as DoT is concerned. It amounts to an 'airworthiness certificate' for Atlas. >Hmm... I wonder if this was a move to head off a confrontation with NASA, >which has been insisting that when it buys a commercial launch from GD, that >somehow becomes a government launch, exempt from licensing...] I had the same thought. DoT has had this in the works for some time however so I doubt it is in reaction to NASA (although I wouldn't be suprised to find the process went faster for this reason). Side note: a Justice Department opinion seems to say that if NASA ever launches anything aside from Shuttle, sounding rockets, and experimental vehicles without a licence from DoT they are in violation of the law. >Three more applications for such licenses are under review, two [!] from OSC OSC needs one for Pegasus and one for Taurus. The licence is for a launcher and not a company. >American Physical Society complains of lack of scientific justification >for Fred. [Reportedly the politics of envy at work again, i.e. they thought >less money for Fred would mean more for physics. Rotsa ruck.] I don't think this will prevent station funding. Even Congresscritters who would like to kill it won't vote against it. Allen -- +-----------------------------------------------------------------------------+ |Allen W. Sherzer | If you love something, let it go. If it doesn't come back | | aws@iti.org | to you, hunt it down and kill it. | +-----------------------------------------------------------------------------+ ------------------------------ Date: 11 Apr 91 01:47:30 GMT From: agate!typhoon.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Re: comsat cancellations and lawsuits In article <1991Apr10.095549.12310@pbs.org> pstinson@pbs.org writes: >In article <1991Apr9.234822.25971@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: >And they DID fly on another launcher named Ariane after Hughes made >arrangements with ArianeSpace. Then sometime AFTER the satellites were in >orbit Hughes decided they had paid the French more than they wanted to. Why >should NASA have to renegotiate a contract to launch something the French >aerospace company had already orbited? Hughes had a vaild contract with NASA to provide it a service it needed. (Admittedly with extenuating circumstnces), NASA cancelled that contract, without reimbursing Hughes for damages or costs that the cancellation would occur. NASA is not liable because it cost more to launch on Arianne. It is liable because it had to launch on Arianne. -george william herbert gwh@ocf.berkeley.edu ------------------------------ Date: 10 Apr 91 20:12:12 GMT From: tahoe!jimi!herbert!doug@apple.com (Doug Phillipson ) Subject: Re: Space Stations, Money, Startrek In article <1991Apr7.001002.16456@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <10941@ncar.ucar.edu> steve@groucho.ucar.edu (Steve Emmerson) writes: >>Odd. Don't we (i.e. the human species) already know how to live and >>work in space? > >Yes, in the sense that we know some approaches that work. No, in the sense >of knowing all there is to be known about it, and being able to estimate >the effectiveness of new approaches before trying them. > >>Haven't humans spent up to a year in space with no major problems? > >Two humans have done this, without major problems. More data would be >very welcome, since future efforts are unlikely to precisely duplicate >the exact set of conditions under which this was done. We have an >existence proof, but not enough data to confidently draw graphs and >define the boundaries between acceptable and unacceptable conditions. > >>>... One of the things we need to know is what exercise is necessary >>>and why... >> >>Odd. Don't we already know the answer to these questions? > >No. We have vague notions at best. What's wanted is enough detailed >knowledge to guide engineering design of future space activities. That >we do not have. >-- I can't believe that after Skylab and Mir we need MORE data! We built a space shuttle, for heavens sake, from previous data and extrapolation of learned data. The magnificent thing flew the first time with no unmanned trials. Data isn't the problem. Vision, imagination and motivation are the problem. We don't have a clear national goal. I wonder where we would be now if Kennedy hadn't been killed. We would probably at least have a manned Martian base by now. We have some very smart professionals out there and Gigabytes of data they could be drawing on for a real station. I heard that we can't even recreate Apollo because the blueprints are missing. Thats utterly criminal. Heads should roll just for that. To think the American taxpayers spent 25 Billion on a moon program, a quite successful one at that, and we can't recreate it or come close to doing it again after we have already done it once! NO SIR We don't need to spend money on FRED to reaquire DATA we already have. But like I originally stated I would agree to a TAX hike for a REAL STATION. Doug Phillipson My thoughts are my own! ------------------------------ Date: 10 Apr 91 15:14:27 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!samsung!news.cs.indiana.edu!maytag!watmath!watdragon!watyew!jdnicoll@ucbvax.Berkeley.EDU (James Davis Nicoll) Subject: Re: SPACE Digest V13 #364 In article <9104052012.AA24364@ucbvax.Berkeley.EDU>, space-request+@ANDREW.CMU.EDU writes: > >I agree that chemical rockets haven't much future beyond LEO. But I'm > >rather fond of fission torch rockets myself. I want to get there NOW, > >not next year. :-) > > But where can you go? You certainly won't be using fission in MY back > lagrange point (oops, I mean yard) |-) > > Actually, with Ion systems, since the ISP is so high, you can accelerate for > the entire trip. Toward your destination at first, and slowing down > after the half-way point. You'll start out at only a few meters/minute, since > the amount of mass is so low. But after a day you'll be moving 76400 times > faster. after a week, 534800 times, and after a year, 2.7e+7 times. (.90c) > This is all ignoring relativity, of course. As an example, at .9c, a trip to > Alpha Cent. would appear (th those on earth) to take 4.4 years. But you would > feel like it only took about 2.5 years. That's 2 times the speed of light! You might want to consider what mass ratio you think is feasible. Isp for an ion drive is, uh (flip flip flip) 20,000, so the exhaust velocity is 200 km/s. The equation you want to use is M1/M2 = e**V1/Ve where M1 is the mass of the ship & reaction mass M2 is the mass of the ship sans reaction mass V1 is the total change in velocity Ve is the exhaust velocity If you play around with this equation, you'll find that once V1/Ve gets much bigger than 1, M1/M2 gets very large rather quickly. V1 (km/s) M1/M2 50 1.28 100 1.65 200 2.72 400 7.39 800 54.60 1600 2980.96 3200 8,886,110.52 3200 km/s is a bit over .01 C. That would make it over four centuries to Alpha Centauri. This does not, of course, show that using rockets to get very high (tenths of C) delta vees is impossible, but it is impractical with the system you are talking about. Pulsed Fission rockets are listed as having an Isp of 50,000 (Exhaust velocity of 500 km/s), so a mass ratio of 7.39 would get you 1000 km/s delta vee. A mass ratio of 8,886,110.52 (somewhat larger than is now used) would get you 8000 km/s delta vee (about .03 C), which gets you to Alpha C in ~160 years. I have no idea what the Ve is for the fission system the other poster was talking about is. In any case, you can't just assume that the ion drive gives you unlimited delta vee (although being able to get delta vees of 400km/s would make travel within the solar system much less time consuming). 400 km/s delta vee at an acceleration of .1 m/s**2 gives you 46 days of acceleration. If you weren't planning on stopping, you would go 5 1/3 AU before running out of reaction mass. Using half your delta vee, you'd go about 1 1/3 AU during the boost phase, and the same decelerating (ignoring trivialities like orbital mechanics). Much faster than we can do, but it still would take weeks or months to get around within the solar system. I'm sure other posters could do a better job on this subject than I just did. While pointing out the no doubt numerous flaws in the above, try not to char me *too* much :) James Nicoll PS: Relativistic equations to calculate mass ratios give higher values (although the difference is very small for small delta vees) ------------------------------ Date: 10 Apr 91 17:06:19 GMT From: pa.dec.com!rust.zso.dec.com!shlump.nac.dec.com!engage!pobox!kaplow@decwrl.dec.com (Bob Kaplow) Subject: Re: back-up crews In article <8025@eos.arc.nasa.gov>, brody@eos.arc.nasa.gov (Adam R. Brody) writes... >Since they abolished back-up crews since STS 4, what is the plan if >someone gets sick or for some reason cannont make the flight? I wondered about this as well Friday night. After leaving KSC after the launch of STS-37, I went back to my motel room to follow the news, and heard that Manley Carter, scheduled for the last shuttle flight this year (STS-44?), had been killed in a plane crash along with John Tower. I don't know what NASA does in this case, because I guess it hadn't come up yet. I guess we will find out soon. >How long before the flight do the crew go into quarantine to >prevent catching someone's cold or the flu? One week. This I know for sure, because a friend of mine (Jay Apt) is on the crew of STS-37. His wife held a reception on L-1, and told us that he had been quarantined for a week before the flight. That meant we couldn't see him off in person, and I probably won't get to see him until this August. Bob Kaplow | UUCP: ...!decwrl!pobox.enet.dec.com!kaplow Digital Equipment Corp. | ARPA: kaplow@pobox.enet.dec.com Elk Grove Village, IL | CIS: >INTERNET:kaplow@pobox.enet.dec.com There is no such thing as a free launch! ------------------------------ Date: 10 Apr 91 16:05:01 GMT From: swrinde!mips!spool.mu.edu!cs.umn.edu!sialis!orbit!pnet51!schaper@ucsd.edu (S Schaper) Subject: Re: Advancing Launch Technology I suppose you'd have to put a cow-catcher on a rail-gun launch vehicle... ************************************************************************** Zeitgeist Busters! UUCP: {crash tcnet}!orbit!pnet51!schaper INET: schaper@pnet51.orb.mn.org Aslan is on the move! **************************************************************************** ------------------------------ Date: 10 Apr 91 02:09:46 GMT From: vsi1!hsv3!mvp@ames.arc.nasa.gov (Mike Van Pelt) Subject: Re: Nuclear Rockets In article <10933@ncar.ucar.edu> fhage@virga.rap.ucar.edu (Frank Hage) writes: -If a nuclear rocket develops thrust by vaporizing liquid hydrogen -passing over (through?) the reactor core, and the hydrogen acts -as the coolant, what keeps the reactor from melting "before ignition" -and after the LH fuel has run out? I believe the hydrogen also acts as the moderator, so the reactor can't fission at all unless there's hydrogen flowing through it. -- The powers not delegated to the United States by the | Mike Van Pelt Constitution, nor prohibited by it to the States, are | Headland Technology reserved to the States respectively, or to the people.| (was: Video Seven) U. S. Constitution, Amendment 10. (Bill of Rights) | ..ames!vsi1!v7fs1!mvp ------------------------------ Date: Wed, 10 Apr 91 17:48:40 EDT From: Tommy Mac <18084TM@msu.edu> Subject: Re: SPACE Digest V13 #378 Hey, Hey, Did you see the spacewalk? First in five years, first EVER non-scheduled maintenance by our guys. Think yer robots could do that, Nick? I guess that's one advantage to a Gov. space program. By the time we do have commercial space activity, there will be lots of really experienced astronauts, since they learned on NASA's equipment... Tommy Mac 18084tm@msu Acknowledge-To: <18084TM@MSU> ------------------------------ From: mauxci!eci386!jmm@apple.com (John Macdonald) Date: Wed, 10 Apr 1991 16:36:56 EDT Newsgroups: sci.space X-Mailer: Mail User's Shell (7.1.2 7/11/90) Subject: Re: SPACE Digest V13 #364 In article <9104052012.AA24364@ucbvax.Berkeley.EDU> you write: | [ ... ] As an example, at .9c, a trip to |Alpha Cent. would appear (th those on earth) to take 4.4 years. But you would |feel like it only took about 2.5 years. That's 2 times the speed of light! But, to a photon, it seems like no time has passed at all - that's many times faster than "your" speed. -- sendmail - as easy to operate and as painless as using | John Macdonald manually powered dental tools on yourself - John R. MacMillan | jmm@eci386 ------------------------------ End of SPACE Digest V13 #390 *******************