Date: Fri, 15 Jan 93 05:00:07 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #048 To: Space Digest Readers Precedence: bulk Space Digest Fri, 15 Jan 93 Volume 16 : Issue 048 Today's Topics: ** BUSSARD RAMSCOOP ** averting doom (2 msgs) best food for space? Defuse Xray Experiment ESA press release Galileo Stuck Ribs / Remote Manipulator? (3 msgs) Helium (2 msgs) How much? (was Re: Moon Dust Sold) Let's be more specific (was: Stupid Shut Cost arguements) Saving an overweight SSTO.... Shuttle timetable wanted.... SNC meteorites TPS Systems 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: 13 Jan 93 14:27:50 GMT From: Jason Cooper Subject: ** BUSSARD RAMSCOOP ** Newsgroups: sci.space Just been talking to Lynn Wahl over in my mailbox, and came up with an idea for using a light sail to bring the thing into orbit. The plan is this: 1. Laser-assist out of earth orbit 2. Close approach to sun with sail edge-on to sun (for minimum drag) 3. Sail up to orbit sequence out of the solar system It was broken into a lot more categories in my mail, but I _believe_ that was the gist of it, though Lynn could correct me on here if I'm fatally at fault. The sail could _also_ act as a solar panel. You could probably generate HUGE amounts of energy to store for the long trip on your close approach to the sun. Ah, yes, and the sail can be used as a BRAKE at the destination. Second thing that I've been thinking about... What's the average temperature of space (just "empty" space, not including planets, etc)? I've been reading up about superconductors and found one that apparently can THEORETICALLY reach superconductivity even at 160 degrees kelvin (or was that the real measurement?). Just wondering if the temperature of deep space would help much in the way of cooling the magnetic coils and other components of HUGE concern. Also, does anybody know if a superconducting electromagnet still works? Would that work for the collection magnets? Jason Cooper ------------------------------ Date: Thu, 14 Jan 93 03:37:45 GMT From: Tino Subject: averting doom Newsgroups: sci.astro,sci.space,sci.physics,sci.environment In article <1993Jan13.225015.24673@stsci.edu> vener@stsci.edu (Patricia C. Vener-Saavedra) writes: >Hi there. As I recall, in about a billion years the sun will have >about twice the luminosity it presently has. The average surface of >Earth will be about 100 degrees C. Some lakes and rivers will have >begun to boil. It will not be pleasant for homo sapiens.:-) Don't Panic. Tino -- "Here are the young men, the weight on their shoulders..." - J.D. ---------------------------------------------------------------------------- Purdue University School of Nuclear Engineering ---------------------------------------------------------------------------- ------------------------------ Date: Thu, 14 Jan 1993 05:24:45 GMT From: Marvin Minsky Subject: averting doom Newsgroups: sci.astro,sci.space,sci.physics,sci.environment In article <1993Jan14.033745.11925@gn.ecn.purdue.edu> constant@gn.ecn.purdue.edu (Tino) writes: >In article <1993Jan13.225015.24673@stsci.edu> vener@stsci.edu (Patricia C. Vener-Saavedra) writes: >>Hi there. As I recall, in about a billion years the sun will have >>about twice the luminosity it presently has. The average surface of >>Earth will be about 100 degrees C. Some lakes and rivers will have >>begun to boil. It will not be pleasant for homo sapiens.:-) Sure it will, because by that time we'll be composed of complex polymers of zirconium phosphide or something adequately thermophilic. That is, unless the Rifkins succeed in outlawing evolutionary engineering. ------------------------------ Date: 13 Jan 1993 21:58:48 GMT From: steve hix Subject: best food for space? Newsgroups: sci.space In article rabjab@golem.ucsd.edu (rabjab) writes: >I watched Robinson Crusoe on Mars the other day and got the idea to >put my food in toothpaste tubes. I squezed out all the paste into >jars and used the blender to turn various foods into paste. I'm >having some problems getting the paste in the tubes, however. Does >anyone have suggestions? Are you having fun? :-/ If you're even marginally serious, you could go down to a backpacking store like REI and look for the tubes they sell for bringing honey, peanut butter and the like on trips. They're polyethylene, open at one end with a clip to seal them shut after filling. Reusable, too. RCoM was a pretty bad movie, no? -- ------------------------------------------------------- | Some things are too important not to give away | | to everybody else and have none left for yourself. | |------------------------ Dieter the car salesman-----| ------------------------------ Date: Wed, 13 Jan 93 19:31:58 EST From: Tom Schruefer Subject: Defuse Xray Experiment >With the successful deploy of TDRS-F, STS-54's other primary payload bean >operations. During orbital night, the Diffuse X-Ray Spectrometer will tke >measurements of the x-ray background of the solar system's interstellar >medium. This information will be used to answer questions about a nearb >super nova that scientists believe occurred about 300,000 years ago. Does anyone know which star they are talking about ??? - *====================================================================* | Howard County Public School System, Maryland | |--------------------------------------------------------------------| | From the Collected Works of: | |---------------------------------|----------------------------------| | Tom Schruefer | Bitnet : TCS1@DCC | ::: | Applications Programmer | CompuServe : 76446,1667 | MUSIC *====================================================================* ------------------------------ Date: Thu, 14 Jan 93 16:57:05 CET From: A6%ESOC.BITNET@vm.gmd.de Subject: ESA press release Press Release Nr. 01-93 Paris, 13 Janaury 1993 ESA at the starting blocks of 1993 The calendar of space activities for 1993 is, like every year, full of events and activities taking place all over the world. ESA will again play a chief role in or will be present at the following events at European and at international level. February 1st half Ariane V56: Launch of the American telecommunications satellite Galaxi IV. 22/02 Meteosat 3: Inauguration of the Wallops Island ground station. 2nd half Ariane 5 B1 : First firing test of the Ariane 5 solid rocket booster in Kourou. end STS 55/Spacelab D2 : Second German Spacelab mission with heavy ESA involvement. March 12-21 MUBA, Basel -Switzerland: International trade fair and exhibition. 2nd half STS 56/Atlas 2 : Follow-up of Atlas-1 mission for atmospheric applications and science. April t.b.c. Ariane V57 : Launch of Astra 1C telecommunications satellite with Arsene as seconday passenger. end STS 57/Eureca: Retrieval mission of ESA's Eureca platform. May t.b.c. Ariane V58 : Launch of Hispasat 1B and Insat 2B telecommunications satellites. 05-08 Geotechnica, Cologne- Germany: International geotechnology and Earth sciences trade show and congress. 11-13 Neo-Com 93, Kiev- Ukraine: Telecommunications and information industry fair and conference. 10-13 SPOT and ERS-1 symposium and exhibition, Paris: The results and applications of these two satellites. Co-organized by ESA and CNES. June 11-20 Le Bourget, Paris- France: Space and Air show. ESA will have a large Pavilion open to the general public. 28/6-3/7 COSY: Columbus Symposium in Ischia (Naples), Italy. t.b.c. Ariane 5 M1: First firing test of solid rocket booster with flight structure in Kourou. August 31/8-5/9 MosAeroshow 93, Moscow- Russia : second Russian aviation and aerospace exhibition. Open to the general public. t.b.c. Ariane: 20 years of the Ariane Programme, decided in Brussels in August 1973. September 11-14 2nd ERS-1 Symposium, Hamburg- Germany. t.b.c. Ariane V59 : Launch of Spot 3 and Stella for France. October t.b.c. Ariane V60 : Launch of Intelsat VII-F1 telecommunications satellite. 16-22 IAF, Graz- Austria: Congress and exhibition. The worldwide yearly gathering of space specialists. 19-23 SITEF, Toulouse- France: International market for advanced technologies. t.b.c. ESA Washington Office : 20 years of ESA presence in Washington for close cooperation with NASA. t.b.c. Ariane 5 M2: Second firing test of the Ariane 5 solid rocket booster with flight structure in Kourou. t.b.c. Spacelab: 10th anniversary of ESA's manned space laboratory first launch. November t.b.c. Ariane V61/ MOP-3 : Launch of ESA's meteorological satellite Meteosat MOP-3 and the Mexican telecommunications satellite Solidaridad 1. t.b.c. Maser 6 and Texus 31 sounding rocket launch with major ESA payload participation. December 1st half STS-61/HST servicing : Repair mission of Hubble Space Telescope with ESA astronaut Claude Nicollier on his second shuttle flight. t.b.c. ARIANE V62: launch of DirecTV1 and Thaicom telecommunication satellites. Dates related to launches are very much dependent on different factors (readiness of spacecraft and/or space transportation system/launcher, etc.) and thus remain t.b.c. (to be confirmed) for quite some time. We will timely keep you informed of all these events - and of many more - with a constant flow of information. Regards Hermann Schneider Network Coordinator ESOC (European Space Agency's Operations Centre) ------------------------------ Date: 14 Jan 93 05:34:07 GMT From: justin sullivan Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary In henry@zoo.toronto.edu (Henry Spencer) writes: >Bear in mind that the Galileo malfunction is of a fairly unusual type. >Most failures are subtle things ailing in the innards of the boxes. Well, I'm not one to dig up old ghosts, and I don't mean to sound negative, BUT.. It was 'a fairly unusual type' of problem that took the lives of seven astronauts (seven years ago this month). One could always argue that it wasn't an unusual problem that caused Galileo to have a crippled antenna, but an oversight of hoardes of fine engineers. Nobody's perfect, but when you get so many superbrains together and give them piles of money, they're expected to deliver a perfectly functioning piece of hardware. If they're so damn smart (I believe they are..) things like this shouldn't happen. Either way, 40bps means that my great grandchildren will have to analyze the data. ------------------------------ Date: 14 Jan 93 07:48:50 GMT From: Robert Glock Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary hinz@picard.med.ge.com (David Hinz (hinz@picard.med.ge.com)) writes: : : ..... How feasable : would it be to incorporate a robotic arm manipulator into these designs, : articulated so that it could reach everything on the probe/satellite? : As several readers already have pointed out, a device of that complexity would be *very* likely to break down. Another point: How would one control such an arm? Consider the time the control signals will need to reach a probe near the sun (several minutes) or near the outer planets (several hours!) - no chance to do remote control from earth. But it is equally impossible to send a movement program which will be executed by the vessel's computer, because one cannot foresee what the arm will have to do (e. g. when the stuck antenna ribs will come free). -- Robert Glock Dept. of VLSI Design robert@vlsivie.tuwien.ac.at University of Technology, Vienna Austria / OLD EUROPE ------------------------------ Date: 14 Jan 93 15:10:07 GMT From: "John F. Woods" Subject: Galileo Stuck Ribs / Remote Manipulator? Newsgroups: sci.space,sci.astro,alt.sci.planetary justin@nx30.mik.uky.edu (justin sullivan) writes: >In henry@zoo.toronto.edu (Henry Spencer) writes: >>Bear in mind that the Galileo malfunction is of a fairly unusual type. >>Most failures are subtle things ailing in the innards of the boxes. >One could always argue that it wasn't an unusual problem that caused >Galileo to have a crippled antenna, but an oversight of hoardes of fine >engineers. It is an unusual problem in that most failures of spacecraft are subtle things ailing in the innards of the boxes. This is an assertion about STATISTICS, not some kind of value judgement -- of the total failures of spacecraft components, big mechanical things outside where they can be reached are a small fraction of the list. Now, as to what went wrong with Galileo's antenna, it wasn't an oversight of even one engineer, really -- it was the mechanical damage caused by trucking Galileo across country several times due to missed launch opportunities and the shutdown of the space program after Challenger. The engineers didn't design the joints to withstand that much of that kind of vibration because Galileo shouldn't have been subjected to it -- I'll bet they didn't design the antenna to survive having someone whack it several times with a 15 pound sledgehammer, either. > Nobody's perfect, but when you get so many superbrains together > and give them piles of money, they're expected to deliver a perfectly > functioning piece of hardware. Yeah, and my daughter expected a fat man in a red suit to come down the chimney a couple of weeks ago. The engineers do the best that they can. > Either way, 40bps means that my great > grandchildren will have to analyze the data. No, 40bps means your great grandchildren will have to launch another probe if they want pretty pictures. Most of the science work of Galileo isn't images, and doesn't need the incredibly high bandwidth. ------------------------------ Date: Thu, 14 Jan 1993 05:30:20 GMT From: Christopher Neufeld Subject: Helium Newsgroups: sci.space In article roberts@cmr.ncsl.nist.gov (John Roberts) writes: > >-From: pgf@srl03.cacs.usl.edu ("Phil G. Fraering") > >-\Having a limited education in cryogenics is hampering my understanding >-/of this phenomenon. I understood that helium cannot exist in liquid >-\state at 6 Atm. > >-In general gas laws work the other way: increace the pressure, and the >-"boiling" point of the liquid will increace. > >In general that's true, but don't take any bets on helium - it's extremely >weird stuff. > It's true for helium, too. Unless I'm mistaken, that's a stability condition, and can be proven true for any liquid whose density is greater than the density of the vapour phase. Increasing the pressure of vapour over the liquid would increase the energy required to cross from the liquid to the vapour phase, implying a higher temperature would be required. One way we generate temperatures below 4.2 degrees is to fill a vessel with liquid helium and then pump out the space above the liquid with a very high capacity pump (ours is about the size of a volkswagen, a huge Kinney pump which is far too noisy for my tastes). It is possible to lower the temperature of the liquid to below the lambda point (so that it undergoes a superfluid transition) at 2.174 degrees. We routinely go down to about 0.8 degrees simply by pumping on a liquid helium pool. >Helium can't exist as a *solid* at atmospheric pressure - >its melting point is -272.2 C at 26 atmospheres pressure. The part about >liquid at 6 Atm doesn't sound right. > I just checked my CRC and, technically, you're right. The critical point for He-4 is at 0.227 MPa (2.24 atmospheres) and 5.19 degrees kelvin. Above that pressure the element forms a supercritical fluid, not a liquid. >(Heard recently - helium 3 does form a superfluid, but at a substantially >lower temperature than helium 4. I'm pretty sure I got that right.) > I've heard that too, in the range of a millikelvin, I believe. -- Christopher Neufeld....Just a graduate student | Everyone talks about neufeld@helios.physics.utoronto.ca Ad astra | apathy, but no one does utzoo.utoronto.ca!generic!cneufeld | anything about it. "Don't edit reality for the sake of simplicity" | ------------------------------ Date: Thu, 14 Jan 93 17:24:10 MET From: PHARABOD@FRCPN11.IN2P3.FR Subject: Helium >In general that's true, but don't take any bets on helium - it's >extremely weird stuff. Helium can't exist as a *solid* at atmospheric >pressure - its melting point is -272.2 C at 26 atmospheres pressure. >The part about liquid at 6 Atm doesn't sound right. (J. Roberts, Wed, >13 Jan 93 22:30:31 EST) According to the "Gas encyclopaedia/Encyclopedie des gaz", Elsevier/ L'Air Liquide, liquid helium does exist at 6 Atm. Of course, it is very cold ! BTW, reading again more carefully the article in the CERN courrier, I noticed that the reported experiments were in fact different: 1) the Japanese (KEK) used liquid helium, but pressure and temperature were not specified in the article; 2) the Europeans (CERN) used gaseous helium at 6 Atm, but the temperature was not specified in the article. They intended to use helium-3 and helium-4, solid, liquid and gaseous. J. Pharabod ------------------------------ Date: Thu, 14 Jan 1993 15:54:13 GMT From: Hartmut Frommert Subject: How much? (was Re: Moon Dust Sold) Newsgroups: sci.space higgins@fnala.fnal.gov (Bill Higgins-- Beam Jockey) writes: [discussion on dust price deleted] >I can't find the article with results of the >(cost of Apollo)/(mass of rocks returned) It was on sci.space.shuttle if I remem right. BTW, as I posted there when somebody requested for "any questions": Was the rocks all gain obtained from Apollo ? :) >calculation. How does this compare? I would guess it gives somewhere >around $80M/lb. - Hartmut Frommert Dept of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany -- Eat whale killers, not whales -- ------------------------------ Date: Thu, 14 Jan 1993 08:25:35 GMT From: Gary Coffman Subject: Let's be more specific (was: Stupid Shut Cost arguements) Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1993Jan12.171525.7437@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>Even the SR71 uses fuel to help cool it's titanium skin, and it travels >>more than four times slower than a re-entry vehicle... > >However, it does it for a much longer period. I don't claim to be a >hypersonics guru, but my understanding is that you get *very* different >design solutions for a "hypersonic accelerator" and a "hypersonic cruiser" >(where the former is at hypersonic speeds only briefly, accelerating >towards orbit, and the latter spends much of its operating life there). That's true, but the heat loads go up roughly as the square of the velocity. So a re-entry vehicle is going to experience at least 16 times the heat load of the SR71 during the re-entry period. So a 2 minute re-entry is equivalent in total heat load to a 32 minute SR71 high speed dash. That's not exactly true, the plasma sheath does offer some heat shielding, but it's in the rough ballpark. The design considerations for handling very high heat loads for relatively short periods are, of course, different than those for lower heat loads for longer periods, so it's not strictly comparable. But the point remains that a titanium skin by itself isn't good enough. >The X-20 Dyna-Soar's heat protection was mostly refractory metals, as >I recall. Honeycomb composites. >>The only practical >>metal more refractory than titanium is tungsten... > >A curious claim. The X-15 used titanium only for its *low temperature* >structure, and did not use tungsten at all. Most of its hot structure >was stainless steels of various types. They are heavy, but not impossibly >so. The B-70's wing and main body was stainless-steel honeycomb. I used tungsten as an example of a refractory metal because it's possible to build large structures from it and it's heat resistance is higher than titanium. I know of no other industrially available metal with a higher heat tolerance that can be used for large structures. As was pointed out by someone more knowledgeable, tungsten is highly reactive in a hot oxygen atmosphere, so it's an unsuitable material in practice, though it makes great lamp filaments. Stainless steels are less reactive to oxygen, but lose their strength at much lower temperatures than titanium or tungsten. They aren't completely inert to oxygen at high temperatures either. Honeycomb structures make fine insulators because of the air, or vacuum, gap between layers. They work much the same way as double pane windows in that regard to limit conduction of heat from layer to layer. If the heat load is high, however, the outer layer will ablate away since it can't effectively conduct the heat away due to the fine insulating property of the structure. Ceramic sandwiches like the Shuttle tiles are even more effective insulators while also having high direct resistance to heat and oxidation. NASP reportedly uses carbon-carbon composite honeycombs for strength and heat resistance. Apparently they've found some way to passivate them against oxidation at high temperatures. Diamond films ordinarily burn at relatively low temperatures. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | emory!ke4zv!gary@gatech.edu ------------------------------ Date: Thu, 14 Jan 1993 05:09:22 GMT From: Bruce Dunn Subject: Saving an overweight SSTO.... Newsgroups: sci.space > Allen W. Sherzer writes: > > Note that the 15% margin allows for lots of mistakes. However, if > it turns out that overruns are too great, the program is still > a success. We will know EXACTLY what systems must be weight reduced > to make it work. After a few years of research in those areas, we > will have a working vehicle. We will know not only what systems must be weight reduced, but will get information on how they can be reduced. Doubters may wish to investigate the history of the weight of the shuttle external tank, which was lightened considerably after a few instrumented flights gave detailed information on exactly what stresses it was subject to. -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ Date: 14 Jan 93 05:57:34 GMT From: dowen@vaxc.cc.monash.edu.au Subject: Shuttle timetable wanted.... Newsgroups: sci.space Could someone please post the shuttle launch timetable for June, July and August 1993 ? Also how do I find out about viewing facilities at a launch (do they exist, etc.). Many Thanks, Daryl OWEN. ------------------------------ Date: 14 Jan 93 11:37:00 GMT From: K3032E0@ALIJKU11.BITNET Subject: SNC meteorites Newsgroups: sci.space,sci.astro,alt.sci.planetary Just another update to my update: There are NOT seven, but five Shergottites known. For those who are interested, here is a list of all known SNCs: Shergottites: Shergotty, India Single stone of 5kg fell on August 25, 1865 Zagami, Nigeria Single stone of 18kg fell on October 3, 1962 Allan Hills ALHA77005 Single stone of 482g found in Antarctica 1977 Elephant Moraine EETA79001 Single stone of 7942g found in Antarctica 1979 Lewis Cliff LEW88516 Single stone of 13g found in Antarctica 1988 Nakhlites: Nakhla, Egypt 40 Stones (total 40kg) fell on June 25, 1911 La Fayette, Indiana, USA Single stone of 800g known prior to 1931 Governador Valadares, Brazil Single stone of 158g found 1958 Chassignite: Chassigny, France One or more stones of 4kg fell on Oct.3, 1815 Two interesting facts: * Three Shergottites were recovered in Antarctica, but not a single Nakhlite or Chassignite was found there. * Zagami and Chassigny both fell on October 3. This may be a simple co- incidence, but possibly the meteorid stream released by an impact on the surface of Mars is still "alive". Sure enough, there ARE more SNCs on earth. So keep your eyes open... Herbert ------------------------------ Date: 14 Jan 93 03:19:36 GMT From: Wales.Larrison@ofa123.fidonet.org Subject: TPS Systems Newsgroups: sci.space Gary Coffman writes: >A lander presents a blunt surface to the atmosphere and tries to >shed as much velocity as possible by atmospheric braking. The dwell >time is very much longer, and the heat loading much higher. Shuttle >designers originally considered a titanium skin for the Orbiter, >but even a metal as refractory as titanium wasn't up to the job >(besides driving up fabrication costs dramatically), so they chose >to use refractory silicates in the form of tiles. These are very >poor conductors of heat, you can place your bare hand against one >side of the tile while playing an oxy-acetylene torch on the other >and not notice a temperature rise. There has been much progress in >artificial ceramic refractory materials since Shuttle was designed, >and better choices are likely available now. Indeed, special >refractory blankets have replaced tiles in certain non-critical >areas on Shuttle. But copper, or any other metal won't do for a >lander as opposed to a hypersonic plunger like a warhead. I put this data together a while ago, and thought it might be useful to share with the net on this related subject. There are 7 basic types of thermal protection materials - here is a summary of them TYPE EXAMPLES MAXTEMP(F) ADVANTAGES DISADVANTAGES Metallic Columbium 2500 Durable Very Costly Refractories Tungsten Reusable Very Heavy Hard to manuf Superalloys Inconel 617 2000 Durable Limited Temp Haynes 188 1850 Reusable capability Rene 41 1600 Expensive Non-metal Carbon/Carbon 3000 Reusable Very Costly Refractories Silcon Carbide 2700 Heavy Brittle Ceramic Tiles FRCI 2400 Light Wt Durability Reusable Easy to Make High-density Phenolic silica 4000 Heat capacity No reuse Ablators Phenolic Carbon Heavy Insulation required Med/Low Phenolic Cork 4000 Limited heat No reuse Density Filled Silicone capacity Moderately Ablators Filled Expoxy heavy High temp Nextel/Nomex 2000 Reusable Durable Fabrics Non-Rigid Easy to manufacture It is also important to note that the tiles are very light (about 8-9 lbs per cubic foot), whereas some of the metals (tungsten for example) are heavier than lead.... Ablators are also usually pretty heavy, and have definite problems in turn-around since they require replacement each flight. To calculate the maximum temperature seem, it typically scales inversely with the radius of curvature of the leading edge going through reentry -- that is, higher temperatures are seen at sharper points. Thus, on the shuttle, RCC (Reinforced Carbon Carbon) is used on the leading edges along the wings and the nose, whereas ceramic tile is used over the broad flat areas of the wings. For DC-whatever, based upon my back of the envelope calculations, the nose and flaps will probably have to be RCC or a similar material. For the broad areas of the vehicle considering the angles of attack needed for their cross range requirement, they'll need TPS capable of over 2000 F ; using a refractory metal is probably too heavy -- which leaves either tiles, ablators, or superalloys. Ablators are immediately eliminated for turnaround time impacts, and tiles follow somewhat behind. That leaves some of the new superalloys, which are not as light weight as tiles, but hopefully more durable (most are pretty brittle, though, based upon the NASP materials I've worked with ... virtually no ductility, have a tendency to catastrophically fail rather than yield, and are real expensive bitches to make, install, or maintain.) -------------------------------------------------------------- Wales Larrison Space Technology Investor --- Maximus 2.01wb ------------------------------ End of Space Digest Volume 16 : Issue 048 ------------------------------