Date: Tue, 12 Jan 93 05:02:41 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #037 To: Space Digest Readers Precedence: bulk Space Digest Tue, 12 Jan 93 Volume 16 : Issue 037 Today's Topics: Cheap Mars Rocks (was Re: Moon Dust For Sale) Cheap Mars Rock Sources... DC-1 and the $23M NASA Toilet fiber optic cable Let's be more specific (was: Stupid Shut Cost arguements) LRDPA Magellan Update - 01/11/93 One Small Step for a Space Activist... (Vol. 4 No. 1) Railgun in Southwest US (2 msgs) Re; Shuttle Toilet Saving an overweight SSTO.... Shameless Hucksterism to Plague STS-54 Shuttle tiles What was NASA thinking? (2 msgs) 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: Mon, 11 Jan 1993 20:26:04 GMT From: Henry Spencer Subject: Cheap Mars Rocks (was Re: Moon Dust For Sale) Newsgroups: sci.space,sci.astro,alt.sci.planetary In article <1993Jan11.070745.23686@mr.med.ge.com> hinz@picard.med.ge.com (David Hinz (hinz@picard.med.ge.com)) writes: >By what mechanism do these rocks get here? Volcanic action & random launching? >How do they acheive escape velocity? Probably by complex phenomena associated with large impacts. One of the sticking points on declaring the SNC meteorites to be definitely Martian has been the difficulty in explaining precisely how they got off the planet. Getting shrapnel from a large impact off the Moon is not hard, but Mars's escape velocity is rather high for this kind of thing. >Why do they end up so often in >Antarctica? Or are they just more visible there? ... This one's just a sampling effect. Antarctica is a great place for meteorite hunters, because any rock found sitting on the ice *must* be a meteorite -- there's no other way it could get there. Elsewhere, it is hard to tell whether a random rock belongs where it's sitting or not. In particular, if memory serves, there are a few areas of Antarctica where ice flows just sort of terminate, gradually eroded away by wind rather than flowing into the ocean. A meteorite which falls on ice that is heading that way will end up on the surface in the termination area. This concentrates meteorites from large areas over long periods of time. A bonus is that the Antarctic environment is very cold and virtually sterile, preserving the meteorites in very nearly their pristine state. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Mon, 11 Jan 1993 20:51:59 -0600 From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Cheap Mars Rock Sources... In article <93011.111344K3032E0@ALIJKU11.BITNET> writes: >Nobody knows for sure how the SNC came from Mars to Earth, Shed spore pod shells, maybe? -- Phil Fraering |"...Who in the valley shed the poison tear 318/365-5418 |no one knows... pgf@srl02.cacs.usl.edu|An old myth of a mythical hero..." ------------------------------ Date: 11 Jan 93 01:32:01 EDT From: Ethan Dicks Subject: DC-1 and the $23M NASA Toilet Newsgroups: sci.space In article schumach@convex.com (Richard A. Schumacher) writes: >Uhhh... why didn't NASA just reuse the Skylab toilet on Shuttle? Because the Skylab toilet was just a large outhouse in orbit. The system was a very low tech, based on the astronauts filling up plastic bags and chucking them into the waste storage area. The Skylab living quarters were built into the area of the Saturn V normally used for the hydrogen tank in the second stage. The oxygen tank area was where the garbage was stowed. Skylab was never intended to be used enough to fill the entire waste disposal area with waste. The toilet on the shuttle was supposed to be a major breakthrough in orbital waste management. The collected human byproducts were supposed to be dessicated in the vacuum of LEO and (devoid of significant volume) discharged into orbit. You think the STS toilet is expensive? Take a look at the head aboard Fred. Last I heard, there were two competing designs; NASA was not expected to endorse either, but rather combine both designs. BTW, does anyone have the text of the toilet instructions on _2001_? I recall that a still was reproduced in the book of the movie. -ethan ------------------------------ Date: Mon, 11 Jan 1993 16:33:11 GMT From: Brad Whitehurst Subject: fiber optic cable Newsgroups: sci.space In article roberts@cmr.ncsl.nist.gov (John Roberts) writes: > >-From: Mark.Perew@p201.f208.n103.z1.fidonet.org >-Subject: Fiber optic umbilical >-Date: 4 Jan 93 15:30:14 GMT > >-Putting a fiber optic umbilical on a remote sensing platform designed to >-traverse rough terrain seems very odd to me. Can someone explain to me why >-this was done? A few things come to mind such as eliminating the weight >-required for a radio and associated power supply. Also the fiber optic does >-allow for high reliability and high speed data transfer. > >-I'm *not* throwing stones at the Dante folks. I'm just doing some head >-scratching and hoping someone will explain this to me. > >Well, one thing for sure - plans for an Earth-Mars fiber optic link >will have to be scrapped. :-) > >I can imagine the Dante team trying to straighten out the cable by hand, >and that tiny, heartbreaking "snap" (or maybe they didn't hear anything >at all). Commercial fiber optic cable is great in stationary applications, >but it's too easy to stretch it or bend it beyond the radius of curvature >limits. The people who install our fiber optic links put up warning signs >with a drawing of a hangman's noose, implying what will happen to anybody >who tries to move the equipment. :-) > >Does anybody (the phone companies or the military, for instance) use >fiber optic cable that's stiff enough to reduce the risk of breaking? > Speaking to a friend in Pittsburgh who is apparently acquainted with one of the students on the Dante team this weekend, she commented that they had apparently had an intermittent glitch in the fiber cable before they went to Antarctica (N.B., while likely, this is still 2nd hand quasi-rumor). The cable supplier apparently tested the assembly and claimed to find no problem. So, the flaw may have existed all along, and progressed to a complete break in field condition. Actually, fibers can be quite rugged. Isn't there a new version of one of the wire-guided anti-tank missiles that uses a fiber instead of copper, to reduce weight and increase range? Is it operational? The key is to make a cable that is not stiff, I would guess. -- Brad Whitehurst | Aerospace Research Lab rbw3q@Virginia.EDU | We like it hot...and fast. ------------------------------ Date: Mon, 11 Jan 1993 18:19:49 GMT From: "Edward V. Wright" Subject: Let's be more specific (was: Stupid Shut Cost arguements) Newsgroups: sci.space In <1993Jan11.154812.235@ke4zv.uucp> gary@ke4zv.uucp (Gary Coffman) writes: >A warhead re-entry vehicle is not a good model for a lander. A warhead >doesn't attempt to do atmospheric braking. It's shaped like a long narrow >cone, or hypersonic bullet.... A lander presents a blunt surface to the >atmosphere and tries to shed as much velocity as possible by atmospheric >braking. Ah, which lander are you talking about. The Delta Clipper *is* shaped like a bullet. It does not present its blunt surface (base) on entry. It makes a nose-first, high-angle-of-attack entry modelled after an ICBM-warhead trajectory. This was chosen because of the large amount of data available from computer modelling of missile warheads. It seems rather presumptuous to claim you know more than McDonnell Douglas engineers working on the project about what is and isn't possible when you are uninformed on such basic facts as this. >Shuttle designers originally >considered a titanium skin for the Orbiter, but even a metal as refractory >as titanium wasn't up to the job Yet Another Historical Error. Refractory metals were up to the job until NASA doubled the size of the Shuttle orbiter to meet military payload demands. (And some engineers at Rockwell still felt that refractory metals were viable, given sufficient ingenuity. Langley, and possibly other NASA centers have since come up with refractory metals which they believe can do the job. Some of these were considered for use on the fifth orbiter.) ------------------------------ Date: 11 Jan 93 09:47:52 From: David.Anderman@ofa123.fidonet.org Subject: LRDPA Newsgroups: sci.space Back to the Moon Bill to Be Unveiled in San Diego during January - San Diego L5, a chapter of the National Space Society, will publicly release a draft version of the Lunar Resources Data Purchase Act on Thursday, January 28 in Tierrasanta, San Diego. The event will begin at 7 pm at the Tierrasanta Public Library, located at 4985 La Cuenta Drive, and is open to the general public. This legislation, also known as the Back to the Moon bill, would authorize the U.S. government to purchase lunar science data from private vendors. This new cost-saving approach to exploration of the Moon would jump start the long dormant U.S. lunar program, and provide scientists with a more complete understanding of the potentially valuable mineral and elemental resources on the lunar surface. The Lunar Resources Data Purchase Act is planned to be introduced in the 103rd Congress, once comments on the draft bill to be released in January are considered. San Diego L5, founded in 1982, promotes the development and exploration of space through public education, communication with other special interest groups, and political activity. San Diego L5 played a major role in the enactment of the Launch Services Purchase Act, a Federal law that prohibits NASA from launching most space satellites. For more information, please contact Gregory Nemitz, San Diego L5 Publicity Coordinator, at 619/295-3690. --- Maximus 2.01wb ------------------------------ Date: 11 Jan 1993 18:51 UT From: Ron Baalke Subject: Magellan Update - 01/11/93 Newsgroups: sci.space,sci.astro,alt.sci.planetary Forwarded from Doug Griffith, Magellan Project Manager MAGELLAN STATUS REPORT January 11, 1993 1. The Magellan spacecraft continues to operate normally, orbiting Venus 50 times per week and transmitting a carrier signal (plus X-band telemetry) which is precisely tracked by the DSN (Deep Space Network) stations to extract gravity data. 2. Temperatures remain in the expected range. Bay 7 which contains the CDS (Command Data Subsystem), is at 46 degrees C with a cycle depth of 4 degrees. Transmitter B is at 49.2 degrees with a variation of 0.7 degrees. 3. Attitude control continues to be precise. All starcals (star calibrations) over the weekend were successful with only one partial scan. 4. Magellan has completed 6523 orbits; 887 so far in Cycle-4 which will end on May 25, 1993. 5. Following the end of Cycle-4, the Magellan mission will begin a "Transition Experiment" in which the periapsis will be intentionally lowered to allow the atmospheric drag to slow the spacecraft's velocity. This aerobraking maneuver will enable the mission planners to circularize the orbit and gather high-resolution gravity data closer to the poles of Venus. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Choose a job you love, and /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you'll never have to work |_____|/ |_|/ |_____|/ | a day in your life. ------------------------------ Date: Mon, 11 Jan 1993 19:33:16 GMT From: "Allen W. Sherzer" Subject: One Small Step for a Space Activist... (Vol. 4 No. 1) Newsgroups: sci.space,talk.politics.space One Small Step for a Space Activist... Vol. 4 No. 1 - January 1993 By Allen Sherzer & Tim Kyger The San Diego L5 Chapter and David Anderman have come up with a good idea on how to get Lunar probes back to the Moon. The idea is encapsulated in the Lunar Data Purchase Act (LDPA) which has been circulating and which will hopefully be introduced soon. The LDPA would authorize the Administrator of NASA to purchase from the private sector maps of the Moon (chemical, terrain, or gravity). The requirements are simple enough that a 'smaller, faster, cheaper' probe can accomplish the task, which means that the NASA Administrator can fund LDPA activities by simply reprogramming the small amounts of money needed. Note that the bill is an authorization, NOT an appropriation. LDPA may also specify resolution and other details. This approach is far more likely to gain us our goals then the course we have taken in recent years for three reasons. First, by emphasizing commercial procurement of data and not hardware the way is left open for more creative solutions. In addition, those solutions will not be bogged down by the NASA requirements process. Second, a vendor doesn't get paid unless they provide the data; there will be no incentives for dragging out the effort. Third, and most important, is that the bill gets the job done by using our strengths and not our weaknesses. To understand how this is so, one must understand the difference between an Authorization and an Appropriation. Like the rest of the government, there are a series of checks and balances which apply to getting money from the Feds. Each house has Budget Committee which sets overall guidelines for outyear spending. Each year the budget committees pass a budget (usually) early in spring to guide Congressional spending. Next comes Authorization Committees. These committees are where the experts live. Their main function is to be knowledgeable about their area and judge which programs are worth funding and which aren't worth funding. They pass on the merits of projects, both blessing for funding and providing guidelines on how much can be spent. Finally, the Appropriations Committees. They decide how much money the government will spend each year and allocate it to subcommittees who appropriate funds among various projects. They are guided by the Authorization Bill; they cannot appropriate funds to projects not authorized or appropriate more than authorized. Authorization is a work order, Appropriations is the check. That, of course, is the theory. In practice it doesn't work that way. In many cases, authorization bills are passed very late; usually too late to do any good. This makes appropriation bills de facto authorization bills. Thus, the House Appropriations Committees a very powerful place and its chair arguably the most powerful person in the government. Because of their power, space activists have spent a lot of effort trying to pressure Appropriators to do what we want. Several times we have even shut down the office phone of the Subcommittees responsible for funding NASA with calls to fund SEI. These efforts have, to quote the bard, been full of sound and fury, signifying nothing. This is because we have no power. We are out-spent and out-classed by the older Veterans and Housing interest groups which compete with us for funds. So where are we strong? Where have we actually made a difference? The answer is in the House Subcommittee on Space and in the full Science and Technology Committee. Here activists have been instrumental in getting bills passed covering areas from commercial launch service purchase to patent protection for space research. Twice the Committee Chair (Rep. Brown (D-CA)) has received important election help from space activists, and many members on the Committee share our agenda. This brings us back to the LDPA. By AUTHORIZING the program and keeping costs down, we can do the precursor work which the Appropriations Committee to date refuse to fund. The thing to remember is that LDPA accomplishes it by using our strengths, not our weaknesses. This is an example of working faster, better, cheaper; smarter, not harder. Legislative Roundup SSTO/SSRT Freshmen Orientation is taking off. Among others Rep. Torkelson will soon be visited by the Boston chapter. Several other chapters are sending out letters and making initial contacts. If you want to help, contact Tim Kyger at (202) 225-8459. On the inside, Clinton's new Science Advisor is John Gribbin who was at the Office of Technology Assessment. He is neutral about SSTO but most of his staff are strong supporters. Gore will likely be calling the shots but this is good news. Commercial Space The start of the 103RD Congress is near. Time again to continue the process of chipping away at government impediments to commercial space activity. Expect to see some of the tax provisions which didn't make it into last year's NASA bill to be re-introduced. If Clinton is serious about targeted tax cuts to promote investment then odds of passage, even if only as an amendment may be pretty good. Thing to do: 1. Do you have any ideas on what would be good to include in future commercial space legislation? If so, drop a note to Barry Berringer, Care Of Rep. Robert Walker. -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------103 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Mon, 11 Jan 1993 17:06:00 GMT From: PETER YASUDA Subject: Railgun in Southwest US Newsgroups: sci.space In article , ssi!lfa@uunet.UU.NET ("Louis F. Adornato") writes... >uunet!eros.calpoly.edu!jgreen writes: >> I've heard a rumor that some organization (SSI?) has actually >> built a large railgun somewhere in the SW USA. It's apparently >> supposed to be big enough to put small payloads (>5 kg) into >> orbit, though I don't know if they've done that yet. >> >> Is this a rumor or is there some truth to it? It's not a rail gun; it's some kind of gas gun. It's being built by one of the Energy Dept labs. It uses a really big piston to compress hydrogen gas which drives the projectile out the launch tube, which is mounted at a right angle to the piston. Gas is fed into the launch tube as the projectile passes by. The first attempt will be a test with a light projectile. If successful, the plan is to scale it up. Sorry, that's all I recall. I don't even remember where the article appeared. pyy ------------------------------ Date: Mon, 11 Jan 1993 20:24:52 GMT From: kjenks@gothamcity.jsc.nasa.gov Subject: Railgun in Southwest US Newsgroups: sci.space In article ssi!lfa@uunet.UU.NET ("Louis F. Adornato") writes: >Personally, I don't know that a railgun is going to be worth much for >anything other than ASAT and ABM applications. The problem is that a >ground launched body can't attain orbit (at least, not an orbit that >doesn't intersect the surface) without a circularizing burn at >periapsis. This means that you have to carry propulsion (motor and >fuel), GNC hardware (star trackers or a gyro/accelerometer platform, >momentum wheels or an RCS, guidance computer and control hardware), >power and cooling, a shroud capable of protecting the whole shebang >when it exits the launcher in sea level air at better than 17,000 mph >(orbital velocity at 150 mi), aerosurfaces to prevent tumbling, and >probably active control of same, and still retain enough mass >capability for a payload. You also has to survive the launch. With accellerations up to 5 million G, temperatures in the 1000's C range, and some of the most serious electrical and magnetic fields you can find anywhere, you wouldn't want to be fired out of a rail gun. Nor would you want to try to design a payload which could be fired out of a rail gun. But for those of you who don't know what a railgun is, I'll give you a brief intro. This is a VERY high level description, greatly simplified. A rail gun works because of the interaction between an electrical field with a magnetic field called the Lorentz force. If I recall correctly, the basic equation is f = E x B. So you want great big E (electrical) fields and hefty B (magnetic) fields so you get a whole lot of f = mA. Let's see if I can explain using ASCII sketches: NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN <- North end of NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN magnetic field +++++++++++++++++++++++++++++++++++++++++P++++++++ <- Positive rail <- Velocity vector <- P -----------------------------------------P-------- <- Negative rail SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS <- South end of SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS magnetic field Where "PPP" marks the payload or payload carrier, which is a conducting bar touching both rails. A great big current flows through the rails, passing through PPP. This electrical field is perpendicular to the magnetic field, so the PPP is subject to the Lorentz force, f = E x B. Assuming there's little or no friction with the rails (which is very difficult to arrange), the PPP scoots down the rails in a heckuva hurry, accellerating as it goes. Because there is friction with the rails, they erode quickly and have to be replaced after every N launches, where N varies with the friction and wear properties. Since you need to reach orbital velocity in a short distance, you need to have BIG accellerations. This implies the big E fields (hence hefty current along the rails and PPP), big B fields (hence hefty magnets), and low mass (f = mA). We now return you to discussions about the PEACEFUL use of space. -- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office kjenks@gothamcity.jsc.nasa.gov (713) 483-4368 "...Development of the space station is as inevitable as the rising of the sun." -- Wernher von Braun ------------------------------ Date: Mon, 11 Jan 1993 20:33:23 GMT From: Henry Spencer Subject: Re; Shuttle Toilet Newsgroups: sci.space In article <321010b68@ofa123.fidonet.org> Wales.Larrison@ofa123.fidonet.org writes: >>>Uhhh... why didn't NASA just reuse the Skylab toilet on Shuttle? >>Good question. I haven't seen a detailed explanation... > > Actually, I think the primary reason was because the Skylab >toilet used the old empty Saturn tank to dump the wastes into (like >the Skylab trash disposal did)... Nope, the Skylab toilet captured and bagged the solid wastes, because some of the biomedical experimenters wanted them. I don't remember exactly what was done with the urine; I know there was a long squabble about the best approach during Skylab's development. >Skylab toilet was rather large and heavy, and on shuttle they tried >to reduce it down into a "closet" size... There wasn't any particular reason why the Skylab toilet needed to be big or heavy; are you sure? Unlike the original shuttle toilet, it wasn't a mechanical contraption with moving parts. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 11 Jan 93 12:27:25 -0600 From: Bill Higgins-- Beam Jockey Subject: Saving an overweight SSTO.... Newsgroups: sci.space In article <1993Jan11.075346.12742@bby.com.au>, gnb@baby.bby.com.au (Gregory N. Bond) writes: > Suppose DC-X works more-or-less as planned, and they go ahead and > attempt to build a DC-Y/DC-1. And suppose the pollyannas are right > and it bloats and the dry mass goes up. ^^^^^^^^^^ Cassandras? > There are a couple of scenarios here: [...] > 3) The mass overrun is much larger than that. At this point, the > project is lost; however I suspect that (given the findings of the > various reports into the general feasability) this is much less likely > than the previous cases. > > And in any case, you know a lot more than when you started, and you > can do it right next time! If DC-Y flops, there won't BE a next time for SSTO. Not before our teeth fall out. What a Pollyanna. (-: "Read my lips, Hal: Bill Higgins Open the Pod Bay doors!" Fermi National Accelerator Laboratory Bitnet: HIGGINS@FNALB.BITNET (Happy 1st, or -4th, birth- SPAN/Hepnet: 43011::HIGGINS day to Hal 9000 on 12 Jan!) Internet: HIGGINS@FNAL.FNAL.GOV ------------------------------ Date: Mon, 11 Jan 93 15:44:08 PST From: "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov Subject: Shameless Hucksterism to Plague STS-54 Here is a report on the upcoming Shuttle mission from Francis Slakey of The American Physical Society. Is it just me, or does anyone else think that NASA's Shuttle people engage in a little too much hucksterism? I especially find the wake-up calls to raucous music annoying - do those people really find that amusing? Do they do their Christmas shopping at Spencer's Gifts? ______ WHAT'S NEW (in my opinion), Friday, 8 Jan 93 Washington, DC 3. SHUTTLE MISSION STS-54 WILL ADVANCE THE FRONTIERS OF SCIENCE. The seven-day $843M mission is scheduled for a 13 Jan 93 launch. In the "Application Specific Preprogrammed Experiment Culture System Physics of Toys" test, Mission Specialist Susan Helms will play with a "flipping mouse," Mario Runco with "klacker balls", Greg Harbaugh with a basketball, and pilot Don McMonagle with a "balloon helicopter". After recess they can relieve themselves in a test of the new $30M Hamilton Standard Space Toilet. Then, it's on to the Extravehicular Activity test. The Intravehicular Crew Member (Helms) will observe as Extravehicular Crew Member 1 (Harbaugh) and Extravehicular Crew Member 2 (Runco) manipulate each other in the cargo bay. As explained by NASA: "To simulate carrying a large object, the astronauts will carry one another; to simulate how well they can align an object, they will attempt to place each other into brackets in Endeavor's airlock." Francis Slakey (202) 662-8700 The American Physical Society _______ _____________ Dale M. Greer, whose opinions are not to be confused with those of the Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER "Let machines multiply, doing the work of many, But let the people have no use for them." - Lao Tzu ------------------------------ Date: Mon, 11 Jan 93 21:14:50 EST From: John Roberts Subject: Shuttle tiles -From: gary@ke4zv.uucp (Gary Coffman) -Subject: Re: Let's be more specific (was: Stupid Shut Cost arguements) -Date: 11 Jan 93 15:48:12 GMT -Shuttle designers... 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. I think perhaps you mean a propane torch, or butane torch like Mary described. Pulling some numbers from the Rogers report and elsewhere, the leading edges of the Shuttle wings have to withstand heating up to 2750 F, and are made of layers of graphite cloth in a carbon matrix, with the outer layers chemically converted to silicon carbide. The upper fuselage, the coolest portion during reentry, is only heated to about 600 F. The Shuttle has high-temperature and low-temperature ceramic tiles, which are described in this report as being "nearly pure glass" (I had thought they were silica), with nearly 90% of the volume being "air". The low-temperature ceramic tiles are are rated to 1200 F, and the high-temperature tiles to a higher value, but something below wing leading-edge temperatures. While such temperature resistance is admirable, a properly-designed acetylene torch can heat a thermally isolated object to 6000 F (~ 3300 C). I wouldn't expect any trouble melting most ceramics - I've accidentally melted fire bricks that I was using as a backstop for acetylene welding. >From the 1961 CRC handbook, here are some temperature ratings for ceramics and other materials: SAFE CONTINUOUS OPERATING TEMPERATURE / MELTING POINT Material C F / C F -------- ---- ---- ---- ---- Porcelain 1195 2185 / .... .... Alumina (84%) 1400 2550 / .... .... Zircon 1455 2650 / 2500 4530 Silicon carbide 1510 2750 / 2295 4160 (volatilizes) Silica 1620 2950 / 1670 3038 Alumina (96%) 1700 3100 / .... .... Alumina (100%) 1950 3540 / 2050 3720 Zirconia 2316 4200 / 2680 4850 Magnesia .... .... / 2800 5072 Titanium boride .... .... / 2900 5250 Thoria ... .... / 3110 5630 Titanium carbide ... .... / 3125 5660 Tantalum nitride ... .... / 3440 6050 Tungsten ... .... / 3370 6100 Zirconium carbide .. .... / 3520 6370 Graphite ... .... / 3800 6870 Tantalum carbide ... .... / 3850 7025 Hafnium carbide ... .... / 4160 7520 John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 09 Jan 93 17:10:08 GMT From: Ralph Buttigieg Subject: What was NASA thinking? Newsgroups: sci.space Original to: Clarke@Next1.Acme.Ucf.Edu c> Hence the question in the title of my post: What was NASA c> thinking about? Apparently the Saturn engines could have c> been used to build the shuttle vehicle. Why weren't they? c> c> A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable c> boosters would have taken advantage of a history of literally c> dozens of successful flight firings. Plus there would c> have been a much wider range of abort modes. c> But how reusable were the Saturn engines? Then again, how reusable are the SSME... ta Ralph Buttigieg --- Maximus 2.01wb * Origin: Vulcan's World-Sydney Australia 02 635-1204 (3:713/635) ------------------------------ Date: Mon, 11 Jan 1993 20:27:56 GMT From: Henry Spencer Subject: What was NASA thinking? Newsgroups: sci.space In article <3_713_635.02b4e7a50@Kralizec.fido.zeta.org.au> ralph.buttigieg@f635.n713.z3.fido.zeta.org.au (Ralph Buttigieg) writes: > c> A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable > c> boosters would have taken advantage of a history of literally > c> dozens of successful flight firings. Plus there would > c> have been a much wider range of abort modes. > > But how reusable were the Saturn engines? Then again, how reusable are > the SSME... Any regeneratively-cooled liquid-fueled engine ought to be reusable almost indefinitely, if it's mounted on a reusable vehicle. Test-stand experience certainly supports this. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Received: from crabapple.srv.cs.cmu.edu by VACATION.VENARI.CS.CMU.EDU id ac03645; 11 Jan 93 17:57:24 EST To: bb-sci-space@CRABAPPLE.SRV.CS.CMU.EDU Xref: crabapple.srv.cs.cmu.edu talk.politics.space:2080 sci.astro:30349 sci.space:54576 Newsgroups: talk.politics.space,sci.astro,sci.space Path: crabapple.srv.cs.cmu.edu!cantaloupe.srv.cs.cmu.edu!rochester!udel!news.udel.edu!darwin.sura.net!gatech!mailer.cc.fsu.edu!geomag!cain From: Joe Cain Subject: NASA Administrator Message-Id: <1993Jan11.174333.11027@mailer.cc.fsu.edu> Followup-To: talk.politics.space Summary: any new input? Sender: Usenet News File Owner Nntp-Posting-Host: geomag.gly.fsu.edu Organization: Florida State University Geology Dept. Distribution: usa Date: Mon, 11 Jan 93 17:43:33 GMT Lines: 14 Source-Info: Sender is really news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU Following the recent posting I asked my congressman's assistant if he knew of any new information as to a possible new adminstrator for NASA. His response was that the only two names he has seen floated around DC have been Bill Nelson and Sally Ride. He specifically had not heard anything new, nor that there was any action on replacing Goldin. He said that these have been discussed since the election. It sounds like some trial balloons are in the air, likely comments or opinions should be directed to the new administration. Joseph Cain cain@geomag.gly.fsu.edu cain@fsu.bitnet scri::cain (904) 644-4014 FAX (904) 644-4214 or -0098 ------------------------------ End of Space Digest Volume 16 : Issue 037 ------------------------------