Date: Fri, 18 Dec 92 05:05:31 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #565 To: Space Digest Readers Precedence: bulk Space Digest Fri, 18 Dec 92 Volume 15 : Issue 565 Today's Topics: Chase planes DoD launcher use fast-track failures (2 msgs) Greek jet engine (Was: Terminal Velocity of DCX?) Justification for the Space Program (2 msgs) Making Orbit '93 Sea Dragon? Shut up about DC (was Re: DC vs Shuttle capabilities) SSTO Concepts FAQ (2 msgs) Terminal Velocity of DCX? (was Re: Shuttle . . .) Voyager UVS shutdown Wither the ET? 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: 17 Dec 1992 23:51:16 GMT From: steve hix Subject: Chase planes Newsgroups: sci.space In article <1gofeqINN6td@rave.larc.nasa.gov> claudio@nmsb.larc.nasa.gov (Claudio Egalon) writes: >The chase plane that crashed with Valkyrie was being flown by Joe >Walker, the pilot that broke so many records with the X-15. I was >wondering if anyone in the net knows what was the reason for the >crash. My first impression was that it was pilot error but I may be >wrong. Walker had insufficient experience in formation flying, got too close to the B-70 and got caught by trailing wake turbulance, rolled over the top of the B-70's near wing, took off a least one of the vertical stabs and killed himself before the B-70 went down itself. -- ------------------------------------------------------- | Some things are too important not to give away | | to everybody else and have none left for yourself. | |------------------------ Dieter the car salesman-----| ------------------------------ Date: 17 Dec 92 18:59:53 GMT From: Doug Mohney Subject: DoD launcher use Newsgroups: sci.space In article <1992Dec17.110426.8596@ke4zv.uucp>, gary@ke4zv.uucp (Gary Coffman) writes: >In article <1992Dec16.202219.2063@eng.umd.edu> sysmgr@king.eng.umd.edu writes: >>>. With a serious opponent, your space assets would be priority targets. >> >>So, uh, gary, where are the serious opponents supposed to afford A-SATs? hmm? > >The ex-Soviets have a system. Getting into a fight with them would still >be dealing with a serious opponent in my book. Yes, but you imply there's more than the Russians who have ASAT. Could you illustrate who else has demonstrated said technology? And describe the CURRENT state of the SS-9s (?) which were used to pitch them up? They had that capability. Whether it still exists is open to question. Besides, the Russians are our friends. We're buying reactors and science data and a good portion of their research establishment with good old Yankee Dollars. >>If you can kill recon planes, it's damn sight harder to kill sats. > >In principle no, the sats are predictable, the planes aren't. Putting >some "buckshot" in their orbital path is sufficient to knock them down. >In practice planes probably are easier to down because few countries >have space launch capability while they do have AAA, but most planes >in combat zones aren't shot down, and planes are cheaper than spysats too. Depends on what type of plane. The RF-16s are, oh, how much these days? $16-20 million? >>Furthermore, you assumed that the KH-11 is the benchmark (also known as >>the Szabo yardstick) without the resultant drop in costs which would occur if >>you could rapidly deliver sats to orbit. > >Launch costs don't dominate a spysat's cost, at least not one capable of >doing tactical damage assessment. The cost is dominated by the superior >optics required for a orbital spy versus the optics required for an aircraft, >and by the flight control systems required to point the thing at the right >place and compensate for orbital motion and downlink the data. An aircraft's >photorecon equipment is much cheaper because the optics don't have to be as >good because of the lower altitude, the pilot takes care of pointing chores, >and the data is physically returned at the end of the mission. Gary, depending on who you listen to, the KH-12 costs between $800 mil and $1 billion dollars, but it's also a LOT of hardware and fuel to make sure it stays up there for a long long time. Now, SPOT gets 5-10 meter resolution and costs some number ($150-200 million?) below that. A follow-on to SPOT with 1-2 meter resolution will probably cost the same... You CAN build a cheap sat with the resolution needed to do tactical damage assessment. The ex-Sovs did it all the time; they used film rather than rad-spec hardened long-life electronics to transmit images back. You can go cheap on the electronics if you don't want your spysat to live for 5-7 years. I have talked to Ehud, and lived. -- > SYSMGR@CADLAB.ENG.UMD.EDU < -- ------------------------------ Date: Thu, 17 Dec 92 20:47:10 GMT From: Dave Jones Subject: fast-track failures Newsgroups: sci.space Pat (prb@access.digex.com) wrote: > > Actually another case was the YB-49 and YB-50? those were > northrops flying wing prototypes, the turbo-prop and the jet versions. > > They actually flew but had trouble with range, and power. the prop job > needed twin counter rotating props to really develope thrust. > > Plus there were enormous political problems witht he Air Force on the > birds. Too bad, the effort broke jack northrop and he never got to > see his vision carried off in the B-2. Actually he was given a look at a B-2 model while it was still a black program. His reported words were "Now I know why I got to live so long". -- ||------------------------------------------------------------------------ ||Dave Jones (dj@ekcolor.ssd.kodak.com)|Eastman Kodak Co. Rochester, NY | ------------------------------ Date: 17 Dec 1992 23:47:34 GMT From: steve hix Subject: fast-track failures Newsgroups: sci.space In article <1goasfINNnne@mirror.digex.com> prb@access.digex.com (Pat) writes: > >Actually another case was the YB-49 and YB-50? those were >northrops flying wing prototypes, the turbo-prop and the jet versions. Almost. The B-50 was from Boeing, mostly a tricked-up B-29. Northop's YB-35 was prop flying wind. YB-49 was jet-powered version. >They actually flew but had trouble with range, and power. the prop job >needed twin counter rotating props to really develope thrust. The YB-35 was designed to carry 10,000lb load 7,500 miles (with a remaining 15% fuel reserve), economy cruise of 183mph gave it a range of 8,125miles. Top speed was 393mph at 35,000', service ceiling was 40,000'. Not too shabby for a 40's bomber. *Nobody* had much luck with counter-rotating props (save a handful such as the Shackleton and Spitfire XXII). Using them meant that you could get by with a smaller prop diameter for a given powerplant, and they provided more yaw stability...but the stupid gearboxes never worked. The YB-35A switched to normal single props. The XB-35's were converted to single four-bladed props because of the gearbox problems. The jet (YB-49) had only about a 2,800 mile range...but nobody at the time was getting much range out of jets. And the J-35 wasn't the greatest jet engine ever made. >Plus there were enormous political problems witht he Air Force on the >birds. Too bad, the effort broke jack northrop and he never got to >see his vision carried off in the B-2. Ain't politics wonderful. -- ------------------------------------------------------- | Some things are too important not to give away | | to everybody else and have none left for yourself. | |------------------------ Dieter the car salesman-----| ------------------------------ Date: Thu, 17 Dec 1992 18:47:00 GMT From: Roger Wilfong Subject: Greek jet engine (Was: Terminal Velocity of DCX?) Newsgroups: sci.space In Article <1992Dec17.154644.23836@mksol.dseg.ti.com> "pyron@skndiv.dseg.ti.com (Dillon Pyron)" says: > > Imagine a sphere, mounted on an axle. Place a nozzle perpendicular to the > axle, fill the sphere with water and light a fire underneath. If the nozzle is > L shaped, you can make the sphere spin. The porblem is, if the water is not > hot enough when it starts to spin, the rig will stall at the bottom, water will > gush out and kill the fire. > You can get rid of this problem by extending the tube(s) into the sphere about 1/3 of the diameter of the sphere. That way it stays above the water level and the liquid water doesn't spray out. ------------------------------ Date: 17 Dec 92 22:12:02 GMT From: games@max.u.washington.edu Subject: Justification for the Space Program Newsgroups: talk.politics.space,sci.space > In article <1992Dec17.172656.27110@technology.com>, judy@technology.com (Judy McMillin) writes: > |> > |> Can any of you think of any moral or philosophical justification > |> for using huge amounts of taxpayer money to fund the "space > |> program" at all? Not counting, of course, it provides high- > |> pay, high-tech jobs for a bunch of us. > How about, "If we want to avoid the fate of the dinosaurs, at some time in the future (never mind that it might not be in OUR lifetimes), then we better get something up there that can track every asteroid, and comet. Better yet, we better build something that can deflect one of these at some time in the future." The fact that this implies space science, and a good launch system, and several other things is secondary. This is the long term human survival approach. Note: It works VERY well with people who have small children, or who are thinking about having children. (I know, I have a small child, and I think about the long term survival of the race in conjunction with thinking about her growing up, and having kids of her own.) John. ------------------------------ Date: Thu, 17 Dec 1992 21:29:53 GMT From: Jared Dahl Subject: Justification for the Space Program Newsgroups: alt.rush-limbaugh,talk.politics.space,sci.space In article <1992Dec17.172656.27110@technology.com>, judy@technology.com (Judy McMillin) writes: |> |> Can any of you think of any moral or philosophical justification |> for using huge amounts of taxpayer money to fund the "space |> program" at all? Not counting, of course, it provides high- |> pay, high-tech jobs for a bunch of us. Sure. Very easy. How about, "Where do we go now?" We've been everywhere on this planet, it's time to start exploring everything else in the universe. Let's go see what's on Mars, or the moons of Jupiter. We started out in Africa, and spread slowly all around the world. We have moved from walking to riding animals to ships to cars to aircraft. Why not take the next logical step in our evolution? We have always been curious explorers, and we can't change our nature now. Jared Dahl Opinions expressed are mine, not my employer's. Don't send e-mail - I won't get it. ------------------------------ Date: Thu, 17 Dec 1992 21:37:36 GMT From: "David W. Berry" Subject: Making Orbit '93 Newsgroups: rec.arts.sf.announce,sci.space M M A K K IIIII N N GGGG MM MM A A K K I NN N G G M M M M A A KKK I N N N G M M M AAAAAAA K K I N N N G GGGG M M A A K K I N NN G G M M A A K K IIIII N N GGGG OOOO RRRRR BBBB IIIII TTTTTTT 9999 333 O O R R B B I T 9 9 3 3 O O R R BBBB I T 9 9 33 O O RRRRR B B I T 99999 3 O O R R B B I T 9 3 3 OOOO R R BBBB IIIII T 9999 333 Making Orbit Conventions is proud to announce Making Orbit '93! It is a fact that most Americans support the idea of a sound space program that gets real people out into space to do real work. Yet, how far have we really come toward making that a reality? What is being done to make that happen? What are the most promising technologies? Will we really get real people to space soon? Is there anything individuals can do to help make space living attainable for everyone? Are rocket launch systems the way to get there? Or are there other viable launch systems? How much of an influence does science fiction have on science fact and vice-versa? These are just a few of the questions we hope to address at Making Orbit '93, a space oriented hard science and science fiction convention sponsored by Making Orbit Conventions and Space Access Society. Along with answering these weighty questions, we also intend to have some fun along the way. A forum will be provided for many organizations so that information can be shared and enthusiasm for space can be rekindled. This is your chance to share ideas with the experts who are forging the path to the stars, and the science fiction writers who have been furnishing us with dreams. The convention will begin Friday afternoon with two program tracks. One will be a segment sponsored by the Lunar Society, featuring space oriented curriculum ideas and guides for educators. The other will be a mixed track of lighter programming. Then in the evening we really get down to business with an opening ceremony, participant reception and cash bar where you can meet all our speakers. On Saturday and Sunday there will be three programming tracks all featuring space oriented subjects. Two of those tracks will be oriented to hard science and space information with a special emphasis on alternate launch technologies and space policy. A third will be a lighter "Sex in Space" track. On Monday we expect things to wind down but there will still be lots to do. To round things out, in addition to our panels, there will be a dealers' room, art show, and evening hospitality to allow you to share ideas in a more informal atmosphere. We welcome any suggestions you have that would make this event more interesting and fun for you. Please feel free to call us with your ideas for guests, programs or other features. For further info and memberships contact Making Orbit, 909 Marina Village Parkway #237, Alameda, CA 94501 or (408) 321-0154. All this fun and information will be shared in the wonderful atmosphere of the Berkeley Marina Marriott. The hotel features two pools (one is adults only), a large spa, and health club, all set in a peaceful nook right on the waters of the San Francisco Bay in the Berkeley Marina. And all of this at the great convention rate of $79 per room. For hotel info and reservations contact the Berkeley Marina Marriott, 200 Marina Blvd, Berkeley, CA 94710, (510) 548-7920. Speakers Already Planning to Attend Include Max Hunter - Rocket Designer Jerry Pournelle - SF Writer Larry Niven - SF Writer G. Harry Stine - Science/SF Writer Gary Hudson - Space Entrepreneur Jordin Kare - Laser Launch Steve Hoeser - Space Technologist Jim Ransom - Lunar Society Tim Kyger - Congressional Advisor Art Bozlee - Soviet Space Expert J. P. Del Fevero - Space Economics William Gaubatz - SSTO Rick Jurmain - SSTO ------------------------------ Date: Thu, 17 Dec 1992 14:17:18 GMT From: Dennis Newkirk Subject: Sea Dragon? Newsgroups: sci.space In article <1gp19cINNb5b@uniwa.uwa.edu.au> scott@psy.uwa.oz.au (Scott Fisher) writes: >dennisn@ecs.comm.mot.com (Dennis Newkirk) writes: >>lift-off weight 45,360,000 kg. > ^^^^^^^^^^^^^ > ||||||||||||| > No way :-) Perhaps it's living in a place that uses pounds >that has confused you? Using my calculator to convert to pounds (weird units >you guys use in the US) that comes to... 100,001,682 pounds...now that means >very little to me but 45 million kg sure sticks out like a sore thumb to my >metric eyes :-) I think you are the confused one... That is a big number. It's also the weight published in both pounds and kilograms in the Congressional Research Service book I referenced. Check out the quote below. >>2 stage, water launched, pressure fed motors. >>both stages reusable >>recovered by unaided atmospheric and hydrodynamic deceleration only > >Does this mean they are allowed to free-fall back to earth and splash? That was the idea. Here's info on what must be an early Sea Dragon idea, its not quite the same as in the other reference. From : SPACE CARRIER VEHICLES Design, Development, and Testing of Launching Rockets By: Oswald H. Lange and Richard J. Stein Saturn Systems Office George C. Marshall Space Flight Center National Aeronautics and Space Administration Academic Press, New York, 1963 Advances in SPACE SCIENCE and TECHNOLOGY Edited by Frederick I. Ordway, III Editorial Advisory Board Wernher von Braun Leslie R. Shepherd Frederick C. Durant, III George P. Sutton Eugen Sanger Etienne Vassy p.297-298 "The Aerojet-General Corp.in particular has studied a scheme to launch a 600-ft high, three-stage vehicle, weighing 50,000 tons and developing 130,000,000 lb of thrust. The vehicle envisioned would be assembled in a drydock, as pictured in Fig. 221, and towed to the launch site. At the launch site a specially constructed flat-top ship would move into position to act as a service platform. Erection of the vehicle was planned by flooding the launch pontoon as shown in Fig. 222. Fueling and other pre-launch operations would then take place. Upon launch readiness, the flat top tender would be removed, and the carrier vehicle fired from its supporting pontoon." Dennis Newkirk (dennisn@ecs.comm.mot.com) Motorola, Land Mobile Products Sector Schaumburg, IL ------------------------------ Date: 17 Dec 92 14:39:31 -0600 From: Bill Higgins-- Beam Jockey Subject: Shut up about DC (was Re: DC vs Shuttle capabilities) Newsgroups: sci.space In article , strider@clotho.acm.rpi.edu (Greg Moore) writes: > In article ewright@convex.com (Edward V. Wright) writes: >>Depends on your assumptions. I've done some back-of-the-envelope >>calculations. If you can set up an oxygen-extraction plant on the >>Moon, your costs go way down if you land the DC with its LOX tank >>dry. [...] > Right, that works fine once you've built your power-plant > on the moon. I'm talking at first. It seems to me that someone > here is forgetting the middle step of testing and flying the thing. Greg is right. Everyone on the Net should refrain from speculating on the potential applications of the DC series and its derivatives until all these spacecraft are tested and flown. Sheesh. Bill Higgins, Beam Jockey | "Enough marshmallows Fermi National Accelerator Laboratory | will kill you Bitnet: HIGGINS@FNAL.BITNET | if properly placed." Internet: HIGGINS@FNAL.FNAL.GOV | --John Alexander, leader of SPAN/Hepnet: 43011::HIGGINS | "disabling technologies" [*Aviation Week*, 7 Dec 1992, p. 50] | research, Los Alamos ------------------------------ Date: 17 Dec 92 23:41:13 GMT From: Steinn Sigurdsson Subject: SSTO Concepts FAQ Newsgroups: sci.space In article <1992Dec17.141805.9416@aio.jsc.nasa.gov> begley@l14h13.jsc.nasa.gov writes: 13. How often will the SSTO be able to fly? The anticipated turn-around will be about 1 day. Hmm, last figure was two guys(? - Henry you quoted that) to handle the fuelling. Consensus was LOX/LH2 trucks carried about 3 tons, we need 300 tons total - that's 100 trips to your tank farm (which I claim damn well better be over two miles from your launch pad) or about 15 minutes per trip including pumping at each end! Don't think so, even assuming the crew can operate without error for a 24 hour shift (and I ain't going near a LOX truck hooked up by someone who hasn't slept for 24 hours...). So, is turnaround slower or are the ground crew estimates a leetle optimistic? Sounds to me like 12 people on refuelling alone will be necessary for 24 hour turnaround? BTW how does the DC to heat management in orbit? The shuttle has what half-dozen complementary systems, at least one of which forces an abort if it fails? What does the DC do (assuming two days in orbit quoted here is the requirement)? | Steinn Sigurdsson |I saw two shooting stars last night | | Lick Observatory |I wished on them but they were only satellites | | steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? | | "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 | ------------------------------ Date: Fri, 18 Dec 1992 01:25:52 GMT From: Paul Dietz Subject: SSTO Concepts FAQ Newsgroups: sci.space In article steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes: >to handle the fuelling. Consensus was LOX/LH2 trucks carried >about 3 tons, we need 300 tons total - that's 100 trips That's wrong -- the figure was that LH2 tankers carry 3 to 5 tons, but we said nothing about LOX tankers. LOX is much more dense than LH2, and most of the mass of the propellant is LOX. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 17 Dec 92 16:58:00 PST From: "RWTMS2::MUNIZB" Subject: Terminal Velocity of DCX? (was Re: Shuttle . . .) My apologies to the net if this has been discussed before, but I've been pretty far behind in my reading. Anyway, . . . In article <1992Dec3.143759.2535@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >tested. Later it intends to use aerospike engine designs that have >*never* been tested, even on the ground. It will be difficult for This is definitely not true! On Date: Thu, 19 Nov 1992 15:04:00 GMT, "Allen W. Sherzer" writes: >conventional bell nozzles. The GD design could enter base first but had >to have an aerospike nozzle to do it. Since aerospike nozzles have never >flown, that would add another risk to the propulsion system. This is more correct, but not the total story either. In the Spring 1992 (No. 8) issue of Rocketdyne's *Threshold* magazine there is an article "Nozzle Design" by R. A. O'Leary and James E. Bech which states "During the 1960's, Rocketdyne tested numerous aerospike engines, ranging in size from subscale, cold-flow models to this 250,000-pound-thrust oxygen/hydrogen shown at a test stand in Nevada (picture of engine firing). The low altitude performance advantage of the aerospike over conventional bell nozzle is clearly seen". The curve presented looked like this: 1.0 .----.----.----.----.----.----.----.----.----.----. | + T +T T + +/ +/ +/ +/ T +/ | T + / : + / | / 0.9 | / : / Area Ratio = 75:1 Nozzle | / nozzle length = 25% equivalent Efficiency | / conical : / 0.8 | / / Bell Nozzle | / + Aerospike (predicted) : / T Aerospike (test data) | / | 0.7 :----.--/-.----.----.----.----.----.----.----.----. | | | | | | | | 10 100 200 400 800 2000 4000 10000 Pressure Ratio: Pc/Pa Various propellants and both conical (1-D) and axial (2-D) models were been tested. I have heard from several sources that Rocketdyne's original proposal for the Space Shuttle Main Engines used an aerospike design. At the California Space Development Conference held in San Diego in February 1991, Vern Larson from Rocketdyne gave a presentation on the aerospike test program. At that same conference, I asked Max Hunter ("father" of the Delta rocket and a major player in the SSTO field) why it seemed that an aerospike was not baselined for the DC-X or the proposed DC-Y and DC-1. He replied that there was concern regarding the lack of *flight-test data* (he acknowledged that there was plenty of ground test data), in particular for the transonic regime. However, the Rocketdyne article states ". . . from Mach 1 to about Mach 3, *wind tunnel tests* (emphasis mine) indicate a drop in nozzle efficiency due to the slipstream turning into the nozzle region . . . Nevertheless, the interval of time that is spent in this adverse flight regime is short for typical flight trajectories, and overall performance of the aerospike nozzle remains well above that of a conventional bell-type nozzle". Wind tunnel test results and CFD simulations are usually sufficient for design of experimental flight vehicles. Therefore the question remains: If lack of *flight-test* data is seen as the long pole in the tent (holding things up), why isn't it being flown on the admittedly experimental DC-X (and DC-Y)? A reference on aerospike engines that I've seen noted but haven't had a chance to get is: Ballard, R. O., "The Aerospike/Aeroplug Engine: A Technology Development Summary", Sverdrup Technology Inc., MSFC Group, Contract NAS8-37814, 1991. In regards to technology for SSTO, I came across an article by C. E. Tharratt of Chrysler Corporation Space Division in JBIS Vol. 28, pp.3-25, 1975, entitled "SERV - A Reusable Single Stage to Orbit Space Shuttle Concept". It says that a reusable SSTO could be built to NASA requirements with the technology level of the day, except for an added "requirement for large cross range (1500 nautical miles with crew and cargo) and through it, the ability the ability to launch and land in one earth orbit." I seem to recall this as an Air Force driven requirement, and that the original NASA requirement was less stringent. The paper states the original requirement as a return to a preselected [launch?] site every 24 hours (approximately 15 orbits), rather than one orbit. Any idea what the requirement will be for DC-Y (and DC-1)? In order to meet the cross range requirement, the article mentions the weight benefit of using a reusable reradiative heat shield (todays Shuttle tiles) rather than the baselined ablative material, and a major advance in specific impulse from using an activated oxygen/hydrogen engine with a 650 second vacuum specific impulse. It ruled out weight reduction based on materials technology (which today is a most viable technology!). Ben Muniz: President, Rocketdyne Employees Space Society/a chapter of NSS Internet:munizb@rocket.rdyne.rockwell.com w(818)700-5549 h(818)346-6647 ------------------------------ Date: 17 Dec 92 15:44:09 -0600 From: Bill Higgins-- Beam Jockey Subject: Voyager UVS shutdown Newsgroups: sci.space,sci.astro In article <1992Dec16.214714.22600@news.arc.nasa.gov>, murthy_j@jhunix.hcf.jhu.edu (Jayant Murthy) writes: > The Voyager Ultraviolet Spectrometer (UVS) Guest Observer (GO) Program > Scientist, Bob Stachnik/NASA HQ and the UVS GO Project Scientist, Ron > Oliversen/GSFC regretfully announce the termination of the UVS GO program. Ouch! Bummer. The UVS has quietly been observing stellar spectra in the far ultraviolet for many years. To give this announcement some context, I append excerpts from a 1990 posting I wrote. There was an article by J.B. Holberg and others giving results from the UVS observations in *Journal of the British Interplanetary Society* in the past year or so; sorry, don't have the citation handy. ============================================== Now that all the planets on the Voyagers' itinerary have been passed, some of their instruments are essentially useless. The imaging and infrared spectroscopy gadgets have nothing close enough or bright enough to look at anymore. As a one-time stunt (I almost said "one-shot," but then remembered it's a mosaic (-:), Voyager 1 snapped the "family portrait" showing the bodies of the Solar System as little dots. Data are back on the ground, and we oughta see the result any week now. The final frame of the portrait showed the Sun, and in taking it solar heat may have damaged the shutter of one camera permanently. That's okay-- Voyager 1 will never need that camera again. (Barring flying saucer visits.) If there is a scientific purpose to the family portrait, I'm not aware of it. But it's a nice thing to have. Other instruments aboard continue to gather interesting information, which is what JPL means by "routine cruise science." The particles-and-fields stuff reports on the environment at the edge of the solar system; examples include the Plasma Wave System, the Magnetometer, and Low Energy Charged Particle instrument. As the plutonium in the generators decays and power runs low in the years to come, instruments and their heaters will be shut off, starting with the cameras. But the Voyager gang hopes to hit the heliopause-- the boundary between the solar wind and the interstellar wind-- in the next decade or two. So they'll need as many of the P&F experiments running as they can manage. One special case is the Ultraviolet Spectrometer (UVS), which sits on the scan platform with the cameras and the infrared spectrometer. Its primary purpose is for looking at ultraviolet emission and absorption lines in the atmospheres of planets. It is sensitive to wavelengths in the "extreme ultraviolet," between 500 and 1700 angstroms. It happens that not much astronomy has been done in these wavelengths. The galaxy has clouds of interstellar hydrogen. A "Lyman alpha" photon (912 angstroms, 13.6 electron volts) has enough energy to ionize neutral hydrogen. Any photon of wavelength *shorter* than this runs the risk of bumping into a hydrogen atom and getting absorbed as it knocks the electron loose. Now, there is not much hydrogen in interstellar space. There's a lot of room between hydrogen atoms. But over trillions upon trillions of kilometers, the hydrogen adds up. Beyond a few light-years, it's hard to see any light with really short wavelengths, because it gets absorbed in the interstellar hydrogen before it gets to us. Consequently, the ultraviolet telescopes that have flown in space, such as the International Ultraviolet Explorer, have not been given the capability to see extreme ultraviolet (EUV) colors. But the sky isn't as opaque as people thought; you can see *some* distance into space in the EUV, and there is interesting physics going on in nearby stars, especially extremely hot ones. The Voyager UVS instruments are the only currently flying which can make measurements in the EUV. They are small, and their spectral resolution is only about 100 angstroms, but they have lots of leisure time to make long exposures these days. So there's an ongoing program to use the UVS to study a series of stellar targets, which, I imagine, will continue as long as they have the power to operate them. [Hah! --WSH, 1992] I'd speculate that the Voyager studies are valuable precursors for planning such missions as the STS-35 ASTRO observatory, carrying the Hopkins Ultraviolet Telescope [it flew once, and will fly again --WSH, 1992], and the Extreme Ultraviolet Explorer, which will make an all-sky survey. O~~* /_) ' / / /_/ ' , , ' ,_ _ \|/ - ~ -~~~~~~~~~~~/_) / / / / / / (_) (_) / / / _\~~~~~~~~~~~zap! / \ (_) (_) / | \ | | Bill Higgins Fermi National Accelerator Laboratory \ / Bitnet: HIGGINS@FNAL.BITNET - - Internet: HIGGINS@FNAL.FNAL.GOV ~ SPAN/Hepnet: 43011::HIGGINS ------------------------------ Date: 17 Dec 1992 20:07:30 GMT From: Pat Subject: Wither the ET? Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: >or is ET use to remain forever a dream? Did the SOFI (Spray On Foam Insulation) I saw a preseentation on uses for the ET's, and asked about the insulation problem. THe response was, that given the low density of the insulation and the presence of atomicx oxygen, any kernels would not last more then 14 days in orbit, an acceptable level of problem reduction. Now my gut instinct is that the best way to use the ET's would be in a wet workshop configuration, ALA skylab. rig the tanks with either Airlocks, or hardpoints for airlocks, and put flooring and racks in, flooded in the LOX/LH2. then just carry cargo in the Shuttle Bay and load it in, before you put an atmosphere in. they also had lots of applications, using the tanks as carriers. put a truss on hte tank, and then hang stuff off the truss. i saw it, but i couldnt see people going for 2 week expendable space craft. ------------------------------ End of Space Digest Volume 15 : Issue 565 ------------------------------