Date: Fri, 11 Sep 92 05:04:24 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #185 To: Space Digest Readers Precedence: bulk Space Digest Fri, 11 Sep 92 Volume 15 : Issue 185 Today's Topics: 20 Questions About the Delta Clipper 3 booster questions (2 msgs) Climate cycles from Earth's orbital geometry Launch order (was: is this the 50th space shuttle launch?) Mars Direct One Small Step for a Space Activist... Vol 3 No 9 (3 msgs) Pluto Fast Flyby mission goals... QUERY Re: Pluto Direct/ options (3 msgs) Relativity spacesuits SPS SSTO has been achieved 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: Fri, 11 Sep 1992 02:06:22 GMT From: Greg Moore Subject: 20 Questions About the Delta Clipper Newsgroups: sci.space In article amon@elegabalus.cs.qub.ac.uk writes: >> actual wear and tear on the engines. You may find the atmospheric >transit >> has strange affects (look at the British Comet) that negatively >affect >> wear and tear, requiring more maintainance than required. And this > >> > > >The problem with the Comet had nothing at all to do with engines. It >had to do with metal fatigue on the fuselage and an insufficient >number of rip stops. This is not likely to be a problem on DCX as >materials are much better understood now. Not to mention that >simulation, while not perfect, allows problems like this to be >uncovered before prototyping. It even eliminates the need for >fullscale models (as has been noted by Dani I believe) and thus cuts >cost at the same time it cuts design risk. > Sorry, I was not clear above. I did not mean that the Comet faield due to engine problems. The problems were partly a result of extrapolating the known into the unknown. THEIR engineering tests didn't indicate the stress fatigue would be a problem. Bringing the anology to the DC-X and later, I'm curious as to what problems they expect with the cycling of pressure differentials (i.e. sea-level to vacumn) and tempature ranges will have on the engines. Yes, our knowledge is better, but is it enough? >The DCX is a simple craft using off the shelf parts and well >understood technology. There may be some flight regimes in which >there is something to be learned, but I suspect there is not much >from a science viewpoint. Unlike other vehicles built in the past, >its design is not a research project. This is a skunkworks aviation >project whose only goal is operational hardware. > The key there is "some flight regimes in which there is something to be learned" I think we might learn a lot. I just hope known of it endangers the craft. ------------------------------ Date: Fri, 11 Sep 1992 00:08:31 GMT From: Nick Szabo Subject: 3 booster questions Newsgroups: sci.space In article <1992Sep10.052322.27424@u.washington.edu> brettvs@u.washington.edu writes: >[1].What makes Titan so expensive? As is normal, cost is a function of economics and politics as well as technology. First, Titan like Delta and Atlas is a reworked ICBM design, not something designed from scratch as a launcher. That may add significantly to the cost, though there has been a notable failure of anybody to build a launcher from scratch that gives big savings (Ariane gives some small savings, but at the cost of reliability, and Atlas has caught up to Ariane on cost with the 2AS). Second, Martin Marietta has a lock on many large government contracts, espically the USAF Titan IV contract, for reasons having little to do with efficiency. The more Martin charges, the more money they make. In their defense, this situation is by no means unique to MM or Titan, and Titan does have an explary reliability record, justifying a bit higher cost per pound in the eyes of rational customers. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: 11 Sep 92 00:28:00 GMT From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: 3 Booster Questions Newsgroups: sci.space In response to Josh's statment about single engines for the booster phase of an HLV. Josh the NLS one booster which as an Atlas II class launcher only uses one STME booster (600,000 lbs thrust) for 20,000 lbs to orbit. Why? Lower labor costs. Titan IV costs much because of all of the labor involved in the build up as well as the reliability issues that others have mentioned. Funny that I did not know this three weeks ago (about NLS having single engine) when I spoke of the single engine "Baby Saturn" approach. I have to up the payload to orbit value to 60,000-65,000 for the F1A/STME combo to orbit. It still costs less than an Altas to fly. A Rockwell engineer I spoke with at the WSC thought the baby Saturn might be as low as 55 million per launch. This gets the cost per lb down to less than $1000 bucks a pound. This is mostly due to labor savings in the booster construction. Reliablity is a large question BUT 65 F1 engines fired without failure during the Apollo program. This does give a baseline for an optimistic flight reliablilty percentage. Dennis, University of Alabama Huntsville ------------------------------ Date: Fri, 11 Sep 1992 03:31:36 GMT From: Chris Gellasch Subject: Climate cycles from Earth's orbital geometry Newsgroups: sci.geo.geology,sci.astro,sci.space,sci.geo.meteorology In article <1992Sep8.214846.17598@mailer.cc.fsu.edu> cain@geomag.gly.fsu.edu (Joe Cain) writes: > > We were just going over some sedimentary cycles in a class >today which related to an article in EOS.* I would >like to find some material which discusses the Milankovitch-type >forcing functions which lead to climate cycles. i.e. > >precesssion of the equinoxes 19, 23 K years >obliquity of Earth's axis 41, 54 K years >eccentricity of orbit 95, 123, 413, and 2035 K years > >I am looking for something about the level of Scientific American with >some pretty pictures that discusses the geologic findings in this >area. This is for a beginning planetary geology class for >non-scientists. Has anyone seen anything recently? > > I am taking a cylcostratigraphy seminar course this semester and we have been looking at papers by A.G. Fischer. He has published quite a number of papers on cylcicity relating to orbital variations. I have some of the papers with me and I will list them. Fischer, A.G. 1981. Climate Oscillations in the Biosphere. In: Biotic Crises in Ecological and Evolutionary Time, M.H. Nitecki. Academic Press. p. 103-131. Fischer, A.G. 1986. Climatic Rythms Recorded in Strata. Annual Review of Earth and Planetary Science. v. 14 p. 351-376. Gilbert, G.K. 1895. Sedimentary Measurement of Geology Time. Jour. Geol. 3:121-127. The first paper deals more with 300 MY "super cycles" but does talk about the shorter Milankovich cylces. Gilbert was one of the first to see these cycles but could not prove it (no radiometric dating). These papers are not as straight forward as you may be looking for but they deal with the subject in a Sed/Strat context. I can look up other, more straight forward, articles if these don't work. Speaking of cycles, does anyone else have input about these Milankovich cycles found in the stratigraphic record? Chris Gellasch cgellasc@ucs.indiana.edu (use this address, not the one in the header) Indiana Univ. -- ------------------------------------------------------------------------------- Chris Gellasch gellasch@emunix.emich.edu ------------------------------------------------------------------------------- ------------------------------ Date: 10 Sep 92 22:41:03 GMT From: "Shadan M. Ardalan" Subject: Launch order (was: is this the 50th space shuttle launch?) Newsgroups: sci.space.shuttle,sci.space In article sasdhb@lizard.unx.sas.com (Doug Brann) writes: > >In article <1992Sep10.152507.19177@unocal.com>, stgprao@st.unocal.COM (Richard Ottolini) writes: >> >>The LA Times said so. >>But I see the number sts-47 used here. >>How many have actually been launched so far? > >This is the 50th shuttle mission. The STS numbers do not match the number >of missions. The numbers are assigned when the mission is planned and due >to delays and schedule changes the STS numbers became out of order. For >example STS-50 was the Columbia Microgravity Lab a couple of months back and >was the 48th shuttle mission. The Voyager's were not launched in order either. The numbering of the Voyager's was not based on launch order.... Instead, NASA based their numbering on their trajectories....... Here`s what I`m talking about.................................... Voyager 1 was launched on September 1977......(i.e., launched second) Voyager 2 was launched on August 1977.........(i.e., launched first) BUT...... Voyager 1 arrived at Jupiter on March 1979....(i.e., arrived first) Voyager 2 arriver at Jupiter on July 1979.....(i.e., arrived second) Pretty neat, huh :-).... Shadan M. Ardalan ardalan@astrosun.aero.org P.S. BTW, they also arrive at Saturn in that order.... Source: NASA Facts regarding the Voyager Mission ------------------------------ Date: 10 Sep 92 23:37:25 GMT From: Nick Szabo Subject: Mars Direct Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1992Sep4.143843.18127@neptune.inf.ethz.ch> aweder@iiic.ethz.ch (Andreas Michael Weder) writes: >>I'd say, forget about that. Even a manned mission to Mars would cost >>*at least* 500 billion dollars (according to a NASA researcher). > >According to a NASA politician, you mean. > >There is no technical reason why it has to cost that much. See Bob Zubrin's >"Mars direct" proposal for an example of a method that ought to cost about >a tenth that much, total, for the first ten missions. If enough people prod >me, I'll type in my notes from his talk, although there was a good summary >paper about it a year or two ago in JBIS. There is no "technical" reason why anything should cost anything; that is a judgement of economics, and in this case of politics, as well as of technology. I have previously shown that Mars Direct, while being a considerable improvement, would still cost $150 billion for a single 4-astronaut mission to Mars. The two orders of magnitude improvement postulated here is sheer fantasy. We can just as easily improve automated missions to the planets by two orders of magnitude; in fact the improvement in spacecraft technology is proceeding much faster than improvement in space station technology, so that cost breakthroughs are much more likely for automated projects. We will have hundreds of automated stations, sampling robots, propellant plants and much else on Mars before astronauts ever set foot there. In fact the biggest savings in Mars Direct comes from putting an automated propellant manufacturing plant on the surface of Mars. There is also an automated sample-return version of Mars Direct that uses two currently operational launchers, Titan IVs, to return hundreds of kilograms of samples to Earth for a $2 billion, a considerable savings over current Mars sample return designs and a whopping savings over the astronaut version for a similar function. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: Thu, 10 Sep 1992 22:33:22 GMT From: Nick Szabo Subject: One Small Step for a Space Activist... Vol 3 No 9 Newsgroups: talk.politics.space,sci.space First off, I'd like to congratulate Allen on this effort and express my support for this direction. I do have some questions and comments on the specifics, though. > There is an old saying in Mexico: What cannot be remedied > must be endured. With the July House appropriations vote and > with the retirement of Rep. Traxler (D-MI) it looks like Space > Station Freedom is out of remedy mode and into endure mode. > With all its flaws and costs it looks like Freedom WILL be > built (in some form anyway). Fred is still being funded one year at a time. This year it took some significant hits. The probability of Fred being completed, while rising, is still only around 50%, so the market needs to be adjusted by that factor (to start with). The probability of SSF being a significant milestone in space development remains very low; it adds practically no functionality of importance to future endeavors, while consuming a large sum in opportunity costs (cf. my post, "The Opportunity Costs of SSF"). The Shuttle also consumes large amounts of funding, so I applaud this effort to find a superior alternative to the Shuttle. > On the plus side, station supply will mean placing a lot of > mass into LEO, and this could make the market for launch > services a LOT bigger, > ...but non-Shuttle > based resupply could mean that the entire Shuttle program > can be phased out, freeing up roughly three BILLION every year. Shuttle should be phased out with launchers shared by the military and commerce, and eventually by SSTO. Developing a unique capability for one program doesn't make sense, especially a program as inconsquential as SSF. > So what do we need to do? We need to: 1)Fly about 160,000 > pounds of supplies and experiments up and about 50,000 > pounds back down (returned cargo will need low-G return); > 2)Fly four crew to and from Freedom four times a year; and > 3)An Orbital Transfer Vehicle needed to transport payloads > to Freedom (this is needed since we are eliminating > Shuttle). I don't understand the 160,000 pounds. Shuttle only carries 50,000 pounds. What in blazes does #3 mean? We only need to circularize at 300 nm, normal launchers can do that. > A heavy lift vehicle would be one way to meet requirement one. > such an HLV would lift 100,000 pounds to Freedom orbit and would > carry a reusable logistics module. The logistics module would > have an aerodynamic shape (perhaps like DC-Y or an Apollo > capsule) and be capable of returning 20,000 pounds to Earth. I thought you said we need 160,000 pounds? In any case, why can't we use Titan IV? At 40,000 pounds, it can carry nearly as much as the Shuttle. > Such an HLV should be a commercial procurement where the > government buys launch services only (as required by current > federal law). I agree with the commercial aquisition approach, but a launcher custom-made for a single NASA program is a very poor candidate for commercial aquisition. This service has a politically risky future, both in terms of funding SSF and non-use of the Shuttle. A 50% chance of funding with a 25% chance of NASA actually using the service instead of Shuttle gives a 87% chance that the company will lose its shirt trying to develop the beast. > Two candidates are Heavy Lift Delta (see One > Small Step... Vol. 2 No 2) and Titan V (see One Small > Step... Vol. 2 No 3). Both manufacturers have already offered > to sell launch services for either vehicle for less than $200 > million per launch (including development costs). MM already charges $280 million for Titan IV; how are they going to launch more than twice the payload with the same tech for less than $200 million? It makes more sense to use the Shuttle phase-out to fund new technology, like AMROC and SSTO, along with sharing the existing fleet with military and commerce, instead of stretching out the ancient missiles to even more bizzarre lengths. Titan IV, Atlas 2AS, Ariane 44L, and similarly sized launchers with newer technology should be sufficient for serving a rationally designed space station operation. Again, while we quibble on the specifics, I applaud the direction being taken here for sharing resources between NASA and other space programs, instead of keeping NASA fixed on, and then stuck with, its own limited in-house capabilities. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: 11 Sep 92 00:14:05 GMT From: "Frederick A. Ringwald" Subject: One Small Step for a Space Activist... Vol 3 No 9 Newsgroups: talk.politics.space,sci.space In article <1992Sep10.223322.5189@techbook.com> szabo@techbook.com (Nick Szabo) writes: > Fred is still being funded one year at a time. This year it > took some significant hits. The probability of Fred being > completed, while rising, is still only around 50%, so the > market needs to be adjusted by that factor (to start with). Yes, as a space scientist, I know this feeling all too well. Fred ;-)/2 ------------------------------ Date: 11 Sep 1992 02:09:49 GMT From: kjenks@gothamcity.jsc.nasa.gov Subject: One Small Step for a Space Activist... Vol 3 No 9 Newsgroups: talk.politics.space,sci.space First, kentm@aix.rpi.edu (Michael V. Kent) wrote: >>NASA intends to use only the Shuttle for resupply ONLY until something >>better comes along. Then, aws@iti.org (Allen W. Sherzer) replied: >As it currently stands Shuttle and Freedom together spend all the money >which could go toward a Shuttle replacement. NASA therefore intends >to use the Shuttle forever. Goldin says we should consider the Shuttle program to last "at least" until 2005, but not much beyond that. 12 years != forever. No word on where a Shuttle replacement might come from, or how it would be funded. -- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office kjenks@gothamcity.jsc.nasa.gov (713) 483-4368 "HERE MEN FROM THE PLANET EARTH FIRST SET FOOT UPON THE MOON JULY 1969, A.D. WE CAME IN PEACE FOR ALL MANKIND." ------------------------------ Date: Fri, 11 Sep 1992 04:22:00 GMT From: "Horowitz, Irwin Kenneth" Subject: Pluto Fast Flyby mission goals... Newsgroups: sci.space Folks, Hearing all these wild ideas passed around on this Pluto flyby has led me to try to remind everyone of a few things concerning this mission. First, Staehle is trying to bring back the concept of "faster, better, cheaper" that Goldin is pushing, which was so successful in the '60s. As a result, the primary concern for this mission is COST. After that, is a rapid schedule. Finally, they'll address the performance aspects. As a result, this mission WILL NOT use any exotic or unproven technology, just because they strike someone's fancy. There are a lot more "down-to-Earth" missions that can be used as technology testbeds. No ion thrusters. No aerobrakes. They are also limiting the scientific payload to only those instruments that have been deemed most critical to a Pluto flyby. These include a CCD camera, a UV spectrometer, an IR mapping spectrometer, as well as the radio science that can be done using the main antenna. This means no magnetometer. No dust collectors. Nothing else. The second criterion is schedule. They want to get to Pluto before its atmosphere freezes out, so that it can be studied. As to when that will happen, we can't really predict too well. But the sooner we get there, the better chance we'll have of studying that atmosphere. That means we want a quick development schedule, as well as a short flight time. The current plans are to launch in 1998 on an 8 year direct flight (hopefully). No gravity assists. No secondary encounters. AND NO ORBIT INSERTION! It just can't be done within the contraints of the mission. And finally, on the cost for the mission...Staehle has been given a direct order from Goldin to keep the cost of the entire mission under $400M, and we believe that it can be done. There is to be no cost overruns on this project, or it will be killed by NASA. Remember, the last thing we need is to overdesign this mission like CRAF/Cassini. ------------------------------------------------------------------------------- Irwin Horowitz | Astronomy Department |"Whoever heard of a female astronomer?" California Institute of Technology |--Charlene Sinclair, "Dinosaurs" irwin@iago.caltech.edu | ih@deimos.caltech.edu | ------------------------------------------------------------------------------- ------------------------------ Date: Thu, 10 Sep 92 23:38:37 GMT From: Joshua Bell Subject: QUERY Re: Pluto Direct/ options Newsgroups: sci.space In article <15008@mindlink.bc.ca> Nick_Janow@mindlink.bc.ca (Nick Janow) writes: >henry@zoo.toronto.edu (Henry Spencer) writes: > >> In article <1992Sep10.135754.1491@eng.umd.edu> sysmgr@king.eng.umd.edu >> writes: >> In what? :-) Pluto does have an atmosphere of sorts at the moment, but I'd >> guess it's too thin to do much aerobraking in, even if we knew >> its properties well enough to plan an aerobraking mission, which we don't. > >Would it be possible to aerobrake at Uranus or Neptune, perhaps also using the >atmosphere to change trajectory significantly? This would provide a fast >flight for much of the journey and have the remaining part at a speed slow >enough for aerobraking in Pluto's atmosphere, or at least a much slower pass by >Pluto. It would also allow a mission at Uranus or Neptune. > >I can see lots of problems with this, but sometimes wild ideas are workable. Looking at my National Geographic map from Aug 1990, Uranus is getting rather far from an eyeballed route to Pluto. It'd mean sending the probe out away (maybe 120 degrees or so on the ecliptic) from Pluto, and having it whip around. If the intent is slowing the probe down, you will probably end up with an even slower mission. Neptune is only 50 degrees 'off course'. I can imagine a slingshot (ignoring the fact that you're going against the orbit - can you slingshot that way?), but I'll leave it to the experts to judge on the breaking maneuver. Question for the real experts: A few years back I remember seeing tentative 'maps' of Pluto, based on observing the spectrum of the Pluto-Charon system during the eclipse cycle. The maps were rather simple - large white ice caps, a redish-brown surface, a large black/brown spot on one side, and a smaller white spot on the other. Is there any planning of the probe's to take advantage of what little we know about Pluto and 'aiming' for these spots, as the probe will likely shoot past, not wait around 6 days (?) for Pluto to revolve? Joshua | Tremble only if you build false accounts and stand pridefully upon them | | - Lord Leto II, God Emperor of Dune | | | | jsbell@acs.ucalgary.ca Academic Computing Services, University of Calgary | ------------------------------ Date: Fri, 11 Sep 1992 02:05:07 GMT From: "robert.f.casey" Subject: QUERY Re: Pluto Direct/ options Newsgroups: sci.space Something to consider if you want to areobrake your probe: you'd have to build it to take a lot of wind and blowing. And the weight of an Apollo capsule type heat shield. Probably end up being similar to the weight of a retrorocket. And less predictable and controllable than the rocket engine. ------------------------------ Date: Wed, 09 Sep 1992 16:58:00 -0500 From: Shawn McCarthy Subject: QUERY Re: Pluto Direct/ options Newsgroups: sci.space > Although an orbiter has been discussed, the current mission > design calls for only a flyby. To go into orbit, you need to travel more > slowly, thus flight times are longer. And you need to carry more fuel, > which impacts the size of the instrument payload. All kinds of > tradeoffs. Has the possibility of a light-sail been looked into? use it for accelleration from the 'bright' area near the earth, then brake off Jupiter's light... (more complex than that, but thats the general idea)... ------------------------------ Date: Wed, 09 Sep 1992 16:53:00 -0500 From: Shawn McCarthy Subject: Relativity Newsgroups: sci.space Ok.. you look like you know what ur talking about (considerably more than i do anyway.. :> ) got a question: what if that train is moving just 5mph slower than c (as measured from the station) and i run forwards at 6mph? According to the train, i am moving at 6mph.. what does the station see? (or move a flag foreward at that speed on the outside, so they can see it) ... when the object (me or the flag) moves past c according to the station, what happens? or is that a case of the train being shorter (from the station) so the speed really ISN'T faster than c..? ------------------------------ Date: Fri, 11 Sep 92 02:14:58 GMT From: "Amy L. Cooprider" Subject: spacesuits Newsgroups: sci.space Does anyone know the latest figures for how much a spacesuit weighs?? I`ve heard of figures between 150 and 300 pounds. This is somewhat trivial... I only need the values to compute the payload of a vehicle for my senior design course. Thanks!! -ALC ------------------------------ Date: 10 Sep 92 22:38:54 GMT From: Nick Szabo Subject: SPS Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >Actually, you don't have to fool around with aluminum-oxygen (which is >a hassle as a rocket fuel, because both the aluminum and the aluminum >oxide are solids, where you'd really like liquid and gas respectively). >Jordin Kare's latest laser-launcher design, the heat-exchanger rocket, >needs liquid hydrogen for launch from Earth but would work well enough >on liquid oxygen for a lunar launch. You'd still have to do some of >the same work on chamber/nozzle materials, I expect. After you spent the $trillions needed to get the power plant, power storage, laser, etc. for this launcher system to the moon. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: Thu, 10 Sep 1992 21:11:55 GMT From: "Kevin W. Plaxco" Subject: SSTO has been achieved Newsgroups: sci.space As the subject line says, a Single Stage ascent To Orbit has been achieved a half dozen times already, the last taking place almost 20 years ago. The Lunar module ascent stage achieved lunar orbit without dropping any stages (the lower section of the descent stage was abandoned upon liftoff, serving as a launch platform). The fact that lunar escape velocity is 1/6 that of earth, and that without an atmosphere a 15 km high orbit is stable (for a few orbits at least) and that the reduced forces (due to the lack of aerodynamic stress and the reduced force of gravity) involved lighten the craft substantially, a lunar SSTO was an achievable task in 1969. But what about a martian SSTO? I have seen several discussions about the logistics of a manned (or even unmanned return) mars mission, but I have never seen a proposal for how to achieve mars orbit after the mission has ended. How difficult will this be? Presumably, since numerous people here believe DC-Y will succeed, similar technology will prevail on mars (where the conditions, while more difficult than on the moon, are still easier than on the Earth). But what about an unmanned sample return mission? What would the minimum weight be for a sample return craft capable of achieving mars orbit (or solar orbit)? -Kevin -- -Kevin Be particular ------------------------------ End of Space Digest Volume 15 : Issue 185 ------------------------------