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, 16 Jun 91 01:27:15 -0400 (EDT) Message-ID: <0cKjOge00WBw4NTE4g@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 16 Jun 91 01:27:09 -0400 (EDT) Subject: SPACE Digest V13 #655 SPACE Digest Volume 13 : Issue 655 Today's Topics: Re: Extra Terrestrial Intelligence Re: vacuum energies for propolsion Re: Privatization Re: satellite refuelling Re: Info on spacecraft power storage wanted Re: Self-sustaining infrastructures Re: satellite refuelling Re: Babies in Space Re: Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence) Re: Self-sustaining infrastructures 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: 29 May 91 16:14:08 GMT From: dev8g.mdcbbs.com!rivero@uunet.uu.net Subject: Re: Extra Terrestrial Intelligence In article <91143.125932A6014BB@HASARA11.BITNET>, A6014BB@HASARA11.BITNET writes: > (5) Maybe we're the only inhabited planet in the universe... > > Any other comments on this would be greatly appreciated There are two general classes of stars called Population I and Population II stars. Population I stars have heavy elements in them from their creation, while Population II stars are lacking in heavy elements. The designations are reversed chronologically as the Population II stars exist prior to the Population I stars. When a Population II star ends its life and goes nova, that is the source of the heavy elements which get swept up into a Population I star and its planets, which is where the heavy elements that make us up originate. Now then, a quick survey of the stars immediatly surrounding us reveals (surprise) lots and lots of Population II (no heavy elements) stars! No heavy elements are available to the solar systems which accompany these stars, hence, life as we know it is not likely to have evolved, nor would any life forms on these planets have the heavy elements on which our technologies are based. There might very well be many advanced cultures in our galaxy, but it appears that WE are the oldest, most advanced species in this neck of the galatic woods! Being way off in our own little corner may explain a lack of interest on the part of other space-faring races. ========================================================================== \\\\ Michael Rivero | "I drank WHAT!" |"Why bother with marriage?| (. rivero@dev8a.mdcbbs | Socrates -------------------Just find a | )> DISCLAIMER::: |-----------| "Life is CHEAP! |woman you hate == "Hey man, I wasn't |Looking4luv| But toilet paper|and buy her a | ---/ even here then!" |Settle4sex!| is EXPENSIVE!" | house!" | ++++++++++++++++++++++++++++++++++++++++-------------------+++++++++++++++ ------------------------------ Date: 30 May 91 04:22:43 GMT From: cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!unixhub!slacvm!doctorj@ucbvax.Berkeley.EDU (Jon J Thaler) Subject: Re: vacuum energies for propolsion In article <37491@sequoia.UUCP>, jkg@sequoia.UUCP (John K. Gibbons) says: > > On the other hand, we know damned little about what is >happening at the Planck length, where vacuum fluctuations become significant. This is incorrect. Vacuum fluctuations are important and measureable at presently accessible lengths. For example they modify the effective strength of the EM force by about 5% at the highest accessible energies. The possible existence of a lower energy state than our favorite vacuum is highly constrained by the known long lifetime of the universe. ------------------------------ Date: 30 May 91 15:00:12 GMT From: mentor.cc.purdue.edu!pop.stat.purdue.edu!hrubin@purdue.edu (Herman Rubin) Subject: Re: Privatization In article <11682@hub.ucsb.edu>, 3001crad@ucsbuxa.ucsb.edu (Charles Frank Radley) writes: > How will you ensure that the billions simply do not get embezzled if > a private concenr gets it ? > I like the idea of a public government agency habndling sums of > money this big. They are completely open to public scrutiny and > we know exactly where every penny gets spent. > Large sums of money temp people to do some pretty weird things you know, > jjto that is the main problem with the S & L industry.... A government will not openly embezzle the funds, but they will divert them. I suspect that misuse of funds is far more common in the government than in the private sector, and is least in the for-profit sector. Those who invest in something do not want their investment wasted. There is plenty of scrutiny in how every penny gets spent in all firms except those with only a few owners, and even there it is not that free. Look at the income tax laws. This has been reported elsewhere, but the S&L problem was due to the combination of GOVERNMENT insurance and economic pressures combined with deregulation. It was foreseen, the S&Ls were subject to public accounting, and improper activities were only a small part of the problem. -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399 Phone: (317)494-6054 hrubin@l.cc.purdue.edu (Internet, bitnet) {purdue,pur-ee}!l.cc!hrubin(UUCP) ------------------------------ Date: 30 May 91 19:06:59 GMT From: hela!aws@uunet.uu.net (Allen W. Sherzer) Subject: Re: satellite refuelling In article <1991May30.145438.17276@sequent.com> szabo@sequent.com writes: [refuelling sattellites] >You missed another option, which is to decrease the payload mass in >order to allow more stationkeeping fuel for the same launcher. That is a viable option right now. No new technology would be needed. The fact that it isn't done indicates that it is not a good tradeoff. In other words the capability lost by reduced mass translates to less cash flow which would make the satellite unprofitable. >For most satellites, the cost of a refueling mission will not be >significantly smaller than the cost of launching a new generation, more >capable satellite. Depdend on the cost. If I can refuel the satellite for less than $100M it is likely to be worth it. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ Date: 29 May 91 21:32:52 GMT From: van-bc!rsoft!mindlink!a752@ucbvax.Berkeley.EDU (Bruce Dunn) Subject: Re: Info on spacecraft power storage wanted There was a bit of a flurry several months ago about a development by Sanyo. Apparently they have a way of making an extremely high capacity capacitor out of activated carbon (presumably coated with an insulating layer). No details were given in the press reports, but for a while the idea of powering electric vehicles from the device was mentioned. This apparently floundered on lack of long term storage capacity of the capacitor. However, if extremely high capacity capacitors can indeed be made, they may make it possible to get short term discharge rates from a battery system much higher than can be supported by the batteries directly. Since battery capacity is often inversly proportional to design discharge rate, peak shaving by a capacitor system might give higher energy storage per unit power supply mass. -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ Date: 31 May 91 03:49:55 GMT From: agate!earthquake.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Self-sustaining infrastructures In article <1991May30.151147.17424@sequent.com> szabo@sequent.com writes: >Not at all. I am assuming that we can decrease payload mass if a >larger launch vehicle is not available and longer lifetime is desired >(it often isn't, BTW). This is a common engineering tradeoff. > A hell of a lot of time, effort and money goes into making a satellite as small as possible NOW. You want to try to get substantial mass reduction beyond that? >BTW, what are the cost proposals for developing refueling infrastructure? >I think it would blow the cost of doing the payload mass/lifetime tradeoff >out of the water. I suspect we are talking $billions for a problem that >costs, at most, a few $million per satellite. > In fact, I'm in the middle of doing such a cost estimate (though a very rough one...) in my spare time. I had intended to wait untill I finished, but... For a 2-man station, of a soviet Mir-type, able to maintain/refuel/repair 50 satellites / year, the OMV to move the satellites around, and the logistical support of this system... approximately $ 5,000 Million to develop/launch 1,500 Million per year to support This comes to $30 million per satellite repaired. This is less than launch costs for most satellites, and therefore cheaper than launching a replacement. I can go into greater detail if there is any interest... Frank Crary ------------------------------ Date: 31 May 91 12:59:09 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: satellite refuelling In article <1991May30.215257.20590@sequent.com> szabo@sequent.com writes: >The real fact is that it is the central planners, not the satellite builders >and operators, who are pushing refueling capability. It's no different from any large scale infrastructure effort. Builders won't add costs to allow refueling when no refueling companies exist and nobody will enter the refueling market without satellites which can be refueled. Again, it's like the early days of avation and the Kelly Act. Without it and the incentives it provided (multi-engines, advanced navigation and large cargo areas) we wouldn't have the aerospace industry we have today. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ Date: 31 May 91 17:29:45 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!ox.com!fmsrl7!wreck@ucbvax.Berkeley.EDU (Ron Carter) Subject: Re: Babies in Space In article <77002@brunix.UUCP> cgy@cs.brown.edu (Curtis Yarvin) writes: >In article <42950@fmsrl7.UUCP> wreck@fmsrl7.UUCP (Ron Carter) writes: >>A fetus floating in amniotic fluid is already experiencing nearly zero-G >>conditions, and has to resist no gravitational loads. >Balls. Buoyancy is not antigravity. I never said it was. However, the stresses on a bone from its difference in density with the flesh surrounding it are minuscule compared to the stress involved in holding up a body against gravity. The gravitational stress is almost completely absent when floating, compared to, say, walking. >When you drop a wrench in a submarine, does it fall to the deck? Or does it >just hang there? (I ought to flame you properly for getting the question completely wrong.) If I raise my arm and drop it when I'm in air in 1 G, it falls very quickly, and the bone takes significant linear and torsional stresses while supporting the arm. If I do it in 1 G in water, the arm falls (due to the greater density of bone and muscle compared to water), but very slowly. The comparative stresses are much smaller. If I did it in 0 G, it would not fall at all. The question is, how great are the biological effects of the difference between 1 G in water and 0 G, for the maturation of bone? I'd bet they're smaller than the difference between 1 G in water and 1 G in air. >A baby in the amniotic sac experiences the same gravitational load as a baby >lying in a parking lot. The difference is that, in the former case, the force >which opposes gravity is buoyancy, which is well-distributed over the body >surface and thus causes minimal stress. The same effect could be achieved >by immobilizing the critter and placing it on an ideal contour couch. Immobilizing someone is not under consideration, and would have effects of its own. Eliminating muscular stresses would not only have effects on the bones, but also on the muscles. ------------------------------ Date: 1 Jun 91 18:29:17 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!jarthur!nntp-server.caltech.edu!iago.caltech.edu!irwin@ucbvax.Berkeley.EDU (Horowitz, Irwin Kenneth) Subject: Re: Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence) In article <7470015@hpfcso.FC.HP.COM>, mll@hpfcso.FC.HP.COM (Mark Luce) writes... >/ hpfcso:sci.space / rivero@dev8g.mdcbbs.com / 10:14 am May 29, 1991 / >In article <91143.125932A6014BB@HASARA11.BITNET>, A6014BB@HASARA11.BITNET writes: > >> (5) Maybe we're the only inhabited planet in the universe... >> >> Any other comments on this would be greatly appreciated > > > There are two general classes of stars called Population I and >Population II stars. Population I stars have heavy elements in them >from their creation, while Population II stars are lacking in >heavy elements. The designations are reversed chronologically >as the Population II stars exist prior to the Population I stars. >When a Population II star ends its life and goes nova, that is >the source of the heavy elements which get swept up into a Population I >star and its planets, which is where the heavy elements that make us up >originate. > >Now then, a quick survey of the stars immediatly surrounding us reveals >(surprise) lots and lots of Population II (no heavy elements) stars! Sorry to burst your bubble here, but Pop I stars far outnumber Pop II stars in "our little neck of the woods." I believe that the numbers are on the order of 1%-2% of the stars in the solar neighborhood are Pop II. However, in the galactic halo, the vast majority of stars are Pop II (since no active star formation is occuring in these regions today). >No heavy elements are available to the solar systems which accompany >these stars, hence, life as we know it is not likely to have evolved, nor >would any life forms on these planets have the heavy elements on which our >technologies are based. > > There might very well be many advanced cultures in our galaxy, but it >appears that WE are the oldest, most advanced species in this neck >of the galatic woods! Being way off in our own little corner may explain >a lack of interest on the part of other space-faring races. > > > I don't know about other nearby stars, but according to an article > > in the April 1991 issue of Astronomy magazine, the Alpha Centauri > > system has a *higher* metal content than the Solar System, and is > > believed to be somewhat older to boot (about 6 billion years). > > Don't write off our neck of the woods just yet... >========================================================================== >\\\\ Michael Rivero | "I drank WHAT!" |"Why bother with marriage?| > (. rivero@dev8a.mdcbbs | Socrates -------------------Just find a | > )> DISCLAIMER::: |-----------| "Life is CHEAP! |woman you hate > == "Hey man, I wasn't |Looking4luv| But toilet paper|and buy her a | >---/ even here then!" |Settle4sex!| is EXPENSIVE!" | house!" | >++++++++++++++++++++++++++++++++++++++++-------------------+++++++++++++++ >---------- ------------------------------------------------------------------------------- Irwin Horowitz |"Suppose they went nowhere?"-McCoy Astronomy Department |"Then this will be your big chance California Institute of Technology | to get away from it all!"-Kirk irwin@romeo.caltech.edu | from STII:TWOK ih@deimos.caltech.edu | ------------------------------------------------------------------------------- ------------------------------ Date: 1 Jun 91 19:23:56 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!samsung!umich!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: Self-sustaining infrastructures In article <1991May31.235412.61@sequent.com> szabo@sequent.com writes: >* The best cost estimate for a four-man station is $120,000 million (GAO). This is a large part of your problem Nick. You look at one station which costs $120B and from that conclude that ALL stations must cost $120B. The GAO doesn't think that is true, why do you? >* You didn't even bother to amortize the $5 billion. During my daughters writing class this morning I did some rough numbers. I (and my trusty HP 12C calculator) came up with the following: Let's assume the station is similar to the design proposed by LLNL and we use a Titan derived HLV for launch. Development costs (in millions of $$): Station: $1,000 OMV: $ 600 HLV: $ 500 ------- $2,100 This is over three years and assume that 1/3 the money is spent in each of the three years. To give our investors a 10% return we must pay back the future value of our investment which amounts to $2,437M. To amortize this over ten years (continuing to pay our investors 10%) will cost $386M per year. For transport we will use the Soyuz (I use Syouz because I know what they cost; if you want another, build it) at $50M each and a Titan derived HLV which costs $250M per launch and lifts 150K pounds. We will buy four launches per year where two are supply runs and two are combination crew/ supply runs. Finally toss in $100M/year for whatever. This comes to: $ 386M - Amortize of station, OMV, and HLV development costs $1,100M - Transport (4 HLVs and two Soyuz) $ 100M - Misc costs ------- $1,586M - Total cost $ 159M - Profit margine of 10% ------- $1,745M - Total price Now we have a station, transport, and supplies for the crew. We also have half a million pounds of stuff we can lift as well to sell. If we can sell this stuff for at least $3500/pound we break even. Now if satellite manufacturers build their satellites with satndard busses and interfaces along with refueling we could lift up fuel and parts. This would allow us to refuel, repair, and upgrade satellites in orbit. If we use 20,000 pounds of material per satellite we could repair and upgrade 25 satellites per year at a cost of $70M per satellite. which looks on the verge of being practical. A few years of learning curve would also make significant reductions to transport costs making it look even better. The problem of course is that even if there where that many satellites to repair we won't see standard busses and refueling facilities. That's because without the station discussed above there's no point. On the other hand, without that station there is no poing in making satellites repairable. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ End of SPACE Digest V13 #655 *******************