Date: Thu, 21 Jan 93 05:05:44 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #067 To: Space Digest Readers Precedence: bulk Space Digest Thu, 21 Jan 93 Volume 16 : Issue 067 Today's Topics: *** BUSSARD RAMSCOOP *** ** MORE BUSSARD RAMSCOOP ** Clementine Clinton's Promises (space) in Charlotte Observer ESA internal PR info 01/93 ESA press release Freedom's orbit Galileo Update - 01/20/93 Goldin's future (2 msgs) I want to be a space cadet JPL Anonymous FTP Site Oak heat shields Planets around nearby sun-like stars RTG's on the Lunar Module Solar sails Soyuz as an ACRV Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 20 Jan 93 17:30:08 GMT From: Jack Coyote Subject: *** BUSSARD RAMSCOOP *** Newsgroups: sci.space In sci.space, henry@zoo.toronto.edu (Henry Spencer) writes: > >Incidentally, to avoid running into the fabled ramscoop speed limit, >you must *not* use an engine design that converts all the kinetic energy >of the incoming gas into heat. Otherwise your thrust will drop to zero >when the incoming gas temperature reaches the exhaust temperature of >your fusion reaction. As with chemical jet engines, kinetic heating >of the gas stream is your *enemy*, not your friend, because the reaction >you're using for power produces a fixed final temperature, not a fixed >temperature rise. The simplest way around this is the Bussard equivalent >of the scramjet: don't slow the gas down much, just heat it as it goes >past. Alas, this has the same sort of problem that scramjets do: to >make a relativistic-combustion ramjet work, whatever heating reaction you >use must be fast FAST *FAST*, because it must happen within microseconds >at the very most. As I recall, this still will not solve the ~.1c speed limit. You still get big-time energy losses from bremsstrahlung (free-free) interactions and from cyclotron radiation. bremsstrahlung: Fancy term for collisions between unbound electrons in a plasma. You WILL get this kind of radiation if you have a hot fusion reaction. Any radiation means energy loss. cyclotron: You have charged particles in a magnetic field, ergo cyclotron radiation. Again, the energy has to come from somewhere, and that somewhere is your accelleration. More hazards/limits: magnetic drag: The large magnetic field will have a (admittedly smaller) interaction with the (unmapped) interstellar magnetic field. dust: Non-magnetic & relativistic (ouch) Bok globules: Blobs of cold dark gas. Rich in hydrogen, but the rapid rise in density is problematic to a ramscoop. etc. Sorry, few solutions, just more problems. Note to flamers: I LIKE the idea, it just needs work. The best way to solve the above requires that people know about them. They haven't been mentioned (that I have seen), so I did. -- "Pound for pound, lame puns are your best entertainment value." -- Gogo Dodo ------------------------------ Date: Tue, 19 Jan 93 20:27:45 PST From: Jason Cooper Subject: ** MORE BUSSARD RAMSCOOP ** Newsgroups: sci.space Just a few questions for those interested or able to reply... 1. I have been advised by somebody that creating antimatter out of the incoming protons, storing them, then dropping them into the stream, is really rather inefficient, since it requires HUGE amounts of input. Getting antimatter made beforehand seems equally impractical. He DID suggest that I might heat up (or otherwise energize) that reaction by other means. Any ideas? A couple of things have become evident (to me at least, though some may disagree). Though they sound great in the beginning, both the antimatter idea and the idea of using a solar sail is seeming less and less practical, since one takes in too much energy, and one firstly is bulky for such a ship and secondly won't accelerate it much anyways. 2. How dense is interstellar hydrogen? I've heard estimates anywhere from one atom per cubic centimeter to one atom every ten cubic centimeters. Anybody have a DEFINITE figure on this? What I'm trying for specifically is an estimate of how big the field's going to have to be to collect REASONABLE amounts of matter. 3. Although unnecessary at the moment, it may be wise to build in a system for storing some of the incoming protons "for a rainy day". Anybody have any concepts for how such a feat can be done? I'm no ASCII artist, so I won't try to draw it, but the internal shape of the engine will be very much like an elipse (medium eccentricity) just overlapping a parabolic form of the same base diameter (ah yes, that's HALF of an elipse, long dimention along the engine's radial center). That is the cavity shape. I'm looking for some sort of device to pull protons out from inside that cavity into a container on the external of the ship. 4. Any ideas for how to SLOW DOWN on the other end? I'm not sure of any myself, but nothing really comes to mind... Figured somebody else might have an idea. 5. What sort of devices could the ship (which I figure will basically be built around one engine, since that engine will be huge) be equipped with to prepare it for conditions at the other end? Just a few questions. If anybody out there wants to play devil's advocate, I'd be glad to take any _mail_ (please, it's easier to carry on a discussion there since I may be missing half of the messages here) from people who'd like to do so. This project, I have just been informed, has been chosen to participate in the INTERNATIONAL science fair in Taiwan, so I'm welcoming ALL input. Jason Cooper ------------------------------ Date: 20 Jan 93 18:08:52 GMT From: "Edward V. Wright" Subject: Clementine Newsgroups: sci.space In <571810c64@ofa123.fidonet.org> David.Anderman@ofa123.fidonet.org writes: >What is the status of Clementine at this time (post-Clinton election)? Clementine is on track for launch earlier next year (February?). It will orbit and map the Moon for two months, then procedure onward for a roundezvous with the asteroid Geographos. ------------------------------ Date: 20 Jan 93 18:15:12 GMT From: "Edward V. Wright" Subject: Clinton's Promises (space) in Charlotte Observer Newsgroups: sci.space In rabjab@golem.ucsd.edu (rabjab) writes: >> B. Support completion of the space station Freedom. >Looks like Clinton is going to make some rather severe cuts in space >projects. And "supporting completion" doesn't mean actual completion. You don't understand. NASA doesn't *want* Space Station Freedom completed. Completing a project means you no longer have job security, which is why these things go on forever. This is also why no one comes right out and opposes a project anymore. Instead, they "support it as a research program" (as in Les Aspin's "I support SDI as a research program" or Gary Coffman's "I support SSTO..."). That way, you not only ensure that nothing useful will ever get built, you also establish a permanent aerospace jobs program, and ultimately discredit anyone who supported the original project as anything more than a jobs program. ------------------------------ Date: Wednesday, 20 Jan 1993 14:59:58 CET From: JLANDEAU@ESOC.BITNET Subject: ESA internal PR info 01/93 Newsgroups: sci.space ******** Ariane V 56 ********** The first Ariane launch of 1993, flight V56, has now been rescheduled for the night from Tuesday 2 to Wednesday 3 February. An Ariane 42P launcher, equipped with two solid strap-on boosters, will place into geostationary transfer orbit the American telecommunications satellite Galaxy IV. The lift-off will take place from the Ariane launch complex nr. 2 (ELA 2) in Kourou, French Guiana, as soon as possible within the following launch window: Kourou time: 21:50 hrs- 22:45 hrs on 2 February GMT/UT : 00:50 hrs- 01:45 hrs on 3 February Paris time : 01:50 hrs- 02:45 hrs on 3 February   ------------------------------ Date: 20 Jan 93 17:54:55 GMT From: Hermann Schneider Subject: ESA press release Newsgroups: sci.space Press Release No. 03-93 Paris, 19 January 1993 The Euro/Russian BION 10 mission completed On 10 January 1993, at 04.16 UT, eight experiments jointly developed by scientists in five ESA member states, Russia and Ukraine, landed in a forest near the city of Karaganda (Kazakhstan), after a space journey of eleven and a half days. The experiments, covering research areas in biology, medicine and cosmic radiation, were carried by the retrievable "Bion-10" satellite, which had been launched from Plesetsk in Northern Russia on 29 December 1992. Due to thermal control problems the satellite had to be landed two days earlier than planned. On the whole the payload does not seem to have been adversely affected by these problems. The flight of these experiments was the result of a cooperation agreement between the European Space Agency (ESA) and the Institute of Bio-Medical Problems (IBMP) in Moscow. A major part of the payload on "Bion-10" was ESA's "Biobox" facility, a fully automatic and programmable incubator for research in gravitational biology, which housed three of the eight experiments jointly prepared by ESA and IBMP. The experiments in "Biobox", dealing with studies in bone tissue and cells under conditions of microgravity, were successfully executed during the first nine days of the mission. The first analyses carried out on some of the samples immediately after their retrieval from Space indicate a reduced mineralization in microgravity, confirming earlier flight results. Three joint experiments were also flown to study the effects of microgravity on the development and ageing of fruit flies, and on the cell structure development of unicellular algae. The fruit fly experiments produced a wealth of high quality data. The algae experiment, which, for scientific reasons had to be executed during the final days of the originally planned thirteen and a half days spaceflight, was unfortunately truncated because of the early return of the spacecraft, and will yield only partial results. The remaining two experiments, parts of which were directly exposed to the space environment, investigated the effects of cosmic radiation on plants and plant seeds, and performed dosimetric studies of the radiation in the "Bion-10" orbit. The results of these experiments will not be known until a few months after their retrieval. As was the case on the four previous "Bion" missions carried out since 1983, the payload provided by IBMP consisted of two Rhesus monkeys, which were subjected to numerous physiological, neurological, behaviourial and other investigations during their stay in Space. According to the first post-flight reports, both animals were in a reasonably good shape after their mission, though one of them had experienced problems with the food supply system after some days in orbit. Pre-launch and post-landing work on most of the experiments, as well as all engineering activities on "Biobox", were done in MOSLAB, the ESA facility built on the IBMP premises in Moscow. ------------------------------ Date: 20 Jan 93 13:48:35 GMT From: "Allen W. Sherzer" Subject: Freedom's orbit Newsgroups: sci.space In article <73695@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: >>>And Alan thinks you'll see a Soyuz sitting on top of a U.S. booster launched >>>from a U.S. facility.... >>Oh, that's a given. The booster may be the Shuttle... > Why do you say that's a given? Because NASA won't crew Freedom without a lifeboat and Soyuz is the only one they will get. > Isn't it cheaper to let the > Russians deliver the Soyuz ACRVs to Freedom? I don't know if they can deliver Soyuz to the Freedom orbit. I would prefer Atlas since it could result in significant cost reductions for other US payloads. Building NASA's ACRV or using Russian transport will not achieve those goals. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------146 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 20 Jan 1993 18:01 UT From: Ron Baalke Subject: Galileo Update - 01/20/93 Newsgroups: sci.space,sci.astro,alt.sci.planetary Forwarded from: PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 GALILEO MISSION STATUS January 20, 1993 The Galileo spacecraft is almost 31 million kilometers, or about 19.2 million miles, from the Earth, receding at more than a quarter of a million miles each day. It is 1.12 astronomical units (104.3 million miles) from the Sun, and has traveled almost 2.6 billion kilometers (1.6 billion miles) since launch, or two- thirds of its total path to Jupiter. The spacecraft is in the dual-spin mode, spinning at just over 3 rpm with the lower part fixed in orientation. It is transmitting coded telemetry at 1200 bits per second over the low-gain antenna. Except for the fact that the high-gain antenna remains undeployed, Galileo's health and performance are excellent. Yesterday the flight team sent commands to pulse the antenna deploy motors 1800 times, concluding ten days of motor hammering this year. Counting the hammering session of December 29-30, 1992, a total of 13,320 pulses have been executed in the latest attempt to free the three stuck antenna ribs. Although there has been some motion in the deployment system and in the antenna, the ribs have not yet been freed. The last remaining action in the plan for the stuck antenna is to spin up the spacecraft to 10 rpm in March; there is little expectation that this will help. Very shortly the Project plans to focus on doing the Galileo mission with the low-gain antenna. ##### ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Every once in a while, /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | try pushing your luck. |_____|/ |_|/ |_____|/ | ------------------------------ Date: 20 Jan 93 17:19:50 GMT From: Pat Subject: Goldin's future Newsgroups: sci.space,talk.politics.space >In article hagen@owlnet.rice.edu (Jeffrey David Hagen) writes: >>Besides, catch a clue about JPL. It is widely considered to be the single most >>bloated, pig-headed, and inefficient part of NASA among industry folks I have I am here in Washington DC, and mostly deal with NASA HQ and GOddard people. The senior Scientist I met who was heavily involved in funding Planetary Science programs (Name withheld due to confidence) Blamed JPL for the cancellation of Magellans Cycle 4-5 imaging. His comments were that JPL can't do mission support for under 50 million/year. In fact, the big push on now is to design probes that bypass NASA infrastructure. NO TDRSS, No SHuttle, NO JPL. direct comms back to the PI's. pat ------------------------------ Date: 20 Jan 93 18:07:11 GMT From: Ron Baalke Subject: Goldin's future Newsgroups: sci.space,talk.politics.space In article <1jk1jmINN5vh@mirror.digex.com>, prb@access.digex.com (Pat) writes... >I am here in Washington DC, and mostly deal with NASA HQ and GOddard people. >The senior Scientist I met who was heavily involved in funding Planetary >Science programs (Name withheld due to confidence) Blamed JPL for the >cancellation of Magellans Cycle 4-5 imaging. His comments were that >JPL can't do mission support for under 50 million/year. Hmmm... sounds like you have your facts garbled. Cycle 4 has never been cancelled. In fact, Magellan has been doing the Cycle 4 gravity mapping since last September, and will complete it this May. Cycles 5 through 7 may be cancelled, but it requires only 30 million *total* to support these last three cycles through 1995. Also from what I hear, Cycle 5 (which consists of the aerobraking maneuvers and improved gravity mapping) may not get cancelled. The Magellan team is being downsized to lower the costs and keep the mission alive. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Every once in a while, /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | try pushing your luck. |_____|/ |_|/ |_____|/ | ------------------------------ Date: Thu, 21 Jan 93 04:54 GMT From: Karl Dishaw <0004244402@mcimail.com> Subject: I want to be a space cadet Fuzzy writes: >Most new guys >(military) who enter AFSPACECOM go to Undergraduate Space Training for a few >months to learn all about rockets and satellites and astrodynamics. Undergraduate Space Training is a 14-week combination of freshman physics and memorizing statistics on AFSPACECOM's assets, one of the worst wastes of $taxes I've seen. I had wonderful time partying in Denver but the only time I learned stuff was talking to instructors outside class (the only time they're allowed to mention stuff that can't fit into a multiple-choice test). TDY pay was nice too--you KNOW a lieutenant's overpaid when he sends money to his parents. :-) Karl sold my soul to Uncle Sam . . . now marked down for resale. ------------------------------ Date: 20 Jan 1993 16:15 UT From: Ron Baalke Subject: JPL Anonymous FTP Site Newsgroups: sci.space,sci.astro,alt.sci.planetary Forwarded from: PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 JPL Pubinfo January 20, 1993 A public access computer site containing information on and images from missions conducted by NASA's Jet Propulsion Laboratory has been opened by the JPL Public Information Office. The site may be reached by modem over phone lines, or by file transfer protocol (ftp) over Internet. Contents of the site include: -- JPL news releases, status reports, fact sheets and other data on JPL missions. -- Images from JPL missions as GIF computer files. These may be displayed on various makes of computers; viewing software may also be downloaded. -- Back issues of JPL's in-house newspaper, Universe. In addition, teacher materials provided by the JPL Public Education Office are planned to be added shortly. Public users of the site currently may connect to it by the following methods: -- By modem over commercial telephone lines to +1 (818) 354-1333. Set parameters to no parity, 8 data bits, 1 stop bit. This line supports speeds up to 9600 bps with the v32/v42bis/MNP5 error correction and compression protocols, and supports up to two callers simultaneously. -- Users with Internet access can use anonymous ftp to pubinfo.jpl.nasa.gov (128.149.6.2). Log on as user ANONYMOUS, then send your city and state (city and country if other than USA) as the password (commas and spaces are ok, up to a total of 15 characters). For more information on this site, please call (818) 354-7170. [Note to Internet users: Although this site is not intended to support interactive communication, your comments or questions are welcome via email to newsdesk@jplpost.jpl.nasa.gov.] ##### ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Every once in a while, /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | try pushing your luck. |_____|/ |_|/ |_____|/ | ------------------------------ Date: Wed, 20 Jan 1993 21:28:50 -0600 From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Oak heat shields \I believe that what the Chinese are reported to be using is oak, not /bamboo. they are also reported to produce a lot of their space \hardware in a refrigerator factory, or soemthing like that. So much /for Western requirements for Level 100 cleanrooms. Back before the big cleanup I could have gotten you a good deal on enough oak to have retrieved a couple Skylabs intact; but we weren't able to sell it, the lumberyards don't take "windfalls" from people's yards, because they might have old nails and stuff in them... as if we don't know where all the nails are... It basically got hauled away with all the other fallen trees. \"Insisting on perfect safety is for people who don't have the balls to live / in the real world." -- Mary Shafer, NASA Ames Dryden Yup. An industry too chicken(explicitave deleted) to learn about post-stone-age devices such as metal detectors turned our potential resource back into trash. I wonder how much they'd be paying for it if it were from virgin forest that species were driven extinct for instead of from our backyard. Needless to say, I think I now support efforts to save the Northern Spotted Owl. If the lumber mills don't want to live in the real world, and throw away (possible total for the area) tens of millions of dollars worth of good oak and pine in a time when everyone could have used financial help in the cleanup, then I don't want to either. God, I think you *could* have heat-shielded several Skylabs with that wood... \------------------------------------------------------------------------------ /Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me. Just so y'all don't think Mary wrote that... -- Phil Fraering |"...Who in the valley shed the poison tear 318/365-5418 |no one knows... pgf@srl02.cacs.usl.edu|An old legend of a mythical hero..." ------------------------------ Date: 20 Jan 93 18:04:31 GMT From: Steve Willner Subject: Planets around nearby sun-like stars Newsgroups: sci.space,sci.astro In article , chico@ccsun.unicamp.br (Francisco da Fonseca Rodrigues) writes: > Does someone know where can I get information about the formation > or the possibility planet formation around the nearby stars? You will probably get better answers in sci.astro. I've cross-posted and directed followups there. As I understand it, the current situation is: 1) Everybody believes that planet formation ought to be a natural part of star formation, at least for single stars and maybe for some multiple star systems too. 2) There is lots of indirect evidence supporting 1) - but no proof. 3) There is not (yet) any single observation that is unambiguously a planet circling another star. But see below. > after that in Astronomy Magazine, about the evidences of planets around the > stars Epsilon Eridani and Gamma Cephei. This research was made by Bruce Camp- > bell, from The Dominion Astrophysycal Observatory, and the article said he > and his team would continue to reaserch others stars, and that they had 5 > more candidates, in a total of 16 stars. The observation is that the radial velocity of the star varies periodically by a very small amount. This variation is interpreted as the "reflex motion" of the star due to one or more orbiting planets. The main problem is that the mass inferred for the orbiting body depends on the angle with which we view the system. If we are viewing from a direction near the pole of the orbit, we see only a small portion of the true velocity variation, and we infer a mass that is too small. Thus it could be that the companions are really faint stars, not planets. If enough systems show variations, it may be possible to rule out the "pole-on" interpretation on statistical grounds. Or for some individual systems, it may be possible to rule out a pole-on orientation. If this has actually been done, I'd like to hear about it. -- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa Cambridge, MA 02138 USA Internet: willner@cfa.harvard.edu member, League for Programming Freedom; contact league@prep.ai.mit.edu ------------------------------ Date: 20 Jan 93 21:29:22 GMT From: shanleyl@ducvax.auburn.edu Subject: RTG's on the Lunar Module Newsgroups: sci.space The RtG supposedly was warm enough to be felt through the astronauts gloves. However the same astronaut (name eludes me) that shared that with me, did not believe that there was significant danger (especially as compared to all the other dangers inherent to the environment they were in when near the RTG). I am not sure how this will post because I am not sure how to post a reply to the group about an individuals post ("Re:..."). I fsomeone would like to share the basic command (ANSWER? REPLY? POST? etc???) I would appreciate it. Moot point if this posts the way I wanted it to (Re: RTG Lunar blah Blah blah). Thanks, Paul Shanley pshanley@humsci.auburn.edu or shanleyl@ducvax.auburn.edu ------------------------------ Date: Wed, 20 Jan 93 17:46:35 EST From: Tom <18084TM@msu.edu> Subject: Solar sails Josh Hopkins: > Jason Cooper: >> >>Hmm, can anybody here think of a way to retract a HUGE sail that's giong >>to be external of all tanks, etc, down close to the hull? >The next question though is _why_ you want to combine a solar sail with a ramjet. Solar sails are fairly slow and ramjets have to be moving very quickly >to work. Solar sails have to be near the sun for efficiency whereas I suspect >bussard ramjets benefit from being outside the solar system (someone want to back me up or shoot me down on this one?). Get a first stage with more thrust. >Or better yet, build a big laser in the solar system and just use the sail for propulsion. It may well be easier than trying to build an interstellar ramjet. About the ramjet: Inside the solar system, you have all those tasty ionized protons from the sun, which is exactly what you need, presumably in a smooth and predictable distribution, mening you could control the engine quite well. On the other hand, the solar wind may be relatively thin compared to outside the solar system. Time will tell. Also, inside the solar system there is probably a lot more floating junk that will interfere with the operation (by killing everyone, for example, when it hits at huge velocities :-). We'll see about that someday, too (I hope!) You are right about the speed differences, but with a laser, you could get a sail up to ramjet speeds, within the solar system, perhaps, before the laser loses it's effectiveness due to distance (scattering, extinction, collimnation, etc.) >> Okay, anyways, >>(no more parentheses anymore) does anybody know of a way to retract this >>solar sail (which must be rigid (but possibly foldable), as it will >>contain solar panels VERY useful for the initial approach >I'd be very impressed if you could combine the function of pv cells with solar >sail material. The sail material must be very thin and strong (as well as a >few other requirements) and should be reflective to a very high degree. Solar >cells must absorb light, and tend to be to thick and heavy to be very useful. True. But, there is a potential advantage. If you could catch the photons, rather than reflect them, you could store half their energy, while still getting the other half as actual momentum. The mass required will have to decrease for this to be realizable, no doubt. >Besides, even if you could make a solar sail the generated power you'd have a >hard time figuring out what to do with it all. A sail big enough to boost an >interstellar probe up to the speeds you require would be intercepting enough >light to power a good sized planet. OK, how about, as long as we are imagining solar sails and ramjets (both ideas, not objects) we also imagine solar cells covered in lcds, which take up very little mass. A stretch, sure, but what the hell. Now, at first, open the lcds, so the sail absorbs. Store this energy, till your battery is full. Now close the lcds so the sail reflects. Once near the heliopause, 86 the sail, run the ship on stored energy, using ion thrust. When up to speed, fire up the ram, away you go! Small glitch: The energy used by the ion thruster is the same energy that could have propelled the sail in the first place. If the difference in mass due to dumping the sail can't increase efficiency after the disadvantages of the mass required for other system, as well as the complexity involved, it's all a waste. Has anyone given any thought to sailing on something besides optical/IR waves? How about a giant radio antenna? X-ray reflectors? -Tommy Mac ------------------------------=========================================== Tom McWilliams |Is Faith a short ' ` ' *.; +% 18084tm@ibm.cl.msu.edu |cut for attaining + . ' (517) 355-2178 -or- 353-2986 | . knowledge? ;"' ,' . ' . a scrub Astronomy undergrad | * , or is it just . . at Michigan State University | '; ' * a short-circuit? , ------------------------------=========================================== ------------------------------ Date: 20 Jan 93 13:55:22 GMT From: "Allen W. Sherzer" Subject: Soyuz as an ACRV Newsgroups: sci.space In article <561810c62@ofa123.fidonet.org> David.Anderman@ofa123.fidonet.org writes: >AW>Oh, that's a given. The booster may be the Shuttle but we will see Soy >AW>being launched for (at the very least) ACRV on US launchers. >Under the terms of the Launch Services Purchase Act, NASA is prohibited >from orbiting non-shuttle-specific payloads. Therefore, >using the shuttle to orbit Soyuz spacecraft contravenes the LSPA. In a perfect world you would be correct. However, it is currently too easy for NASA to declare a payload Shuttle specific. >However, several U.S. commercial vendors can supply launchers that >can easily orbit a Soyuz for a more reasonable price than the shuttle. As you well know, I have long supported exactly this. It is obvious that using non-shuttle based logistics systems are both cheaper and more reliable. The problems are political and not technical. >AW>+----------------------990 DAYS TO FIRST FLIGHT OF DCX---------------- >Does this mean that you are now a Delta Clipper pessimist? Not as long as they seem to be on track. Rest assured that if they ever get off track I will loudly proclaim it. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------146 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ End of Space Digest Volume 16 : Issue 067 ------------------------------