Date: Sat, 20 Mar 93 05:39:44 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #345 To: Space Digest Readers Precedence: bulk Space Digest Sat, 20 Mar 93 Volume 16 : Issue 345 Today's Topics: CD for Pluto Mission Flight time comparison: Voyager vs. Gallileo Grand Plan Just a little tap (was Re: Galileo HGA) Lunar Arctic, pressure, antifreeze (was Re: Lunar ice transport) Magellan Update - 03/19/93 Our Universe not a party Universe? Predicting gravity wave quantization & Cosmic Noise Space Station Redesign: Constellation SR-71 Maiden Science Flight SSTO: A Spaceship for the rest of us Water Simulations Why use AC at 20kHz for SSF Power? 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, 19 Mar 1993 21:50:46 GMT From: Bob Myers Subject: CD for Pluto Mission Newsgroups: sci.space Why a CD? Just because consumer recording technology has moved ahead is no reason to assume that the CD is a good choice for such a project. One of the nicer things about the Voyager record was that it was expected to be reasonably easy to figure out - easier, I suspect, than trying to understand the CD format without shipping a tech from Sony along with the thing! Bob Myers | "One man's theology is another man's belly laugh." myers@fc.hp.com | - Lazarus Long/Robert A. Heinlein | ------------------------------ Date: 19 Mar 93 15:24:02 GMT From: Pat Subject: Flight time comparison: Voyager vs. Gallileo Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: > >No, the fundamental problem is that Galileo really could have used a >trip to the fat farm. Galileo is much, much heavier than the Voyagers, So what is the cause of Galileos weight problem. I know , I know it's a glandular thing :-) But serious, what Extra heavy RTG's, or fat instruments? or spare mass for a locker to jam szabo in, and send him off prospecting for materials:-) pat ------------------------------ Date: Sat, 20 Mar 1993 04:57:07 GMT From: Henry Spencer Subject: Grand Plan Newsgroups: sci.space In article <19MAR199321403759@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: >>CRAF was cancelled because it had overrun its budget massively, and Congress >>was giving clear signals that this would not be tolerated... > >CRAF/Cassini did not overrun its budget... NASA proposed to do both for $1.6G. By the time CRAF died, Cassini alone was going to cost that much (and Congress had been very clear that it had priority over CRAF). "The Space Studies Board has found the cost growth in the Comet Rendezvous Asteroid Flyby and Cassini program to be very frustrating and difficult to understand." -- Louis Lanzerotti, chairman of NRC's Space Studies Board, phone interview by Space News (quoted in the March 1 issue). It's true that a certain amount of Congressional fiddling contributed *somewhat* to this, but when the SSB's chairman says he doesn't know why the costs ballooned the way they did, I have a strange suspicion that he's allowing for the known causes. -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sat, 20 Mar 1993 04:44:15 GMT From: Henry Spencer Subject: Just a little tap (was Re: Galileo HGA) Newsgroups: sci.space In article <1odffsINN9qr@access.digex.com> prb@access.digex.com (Pat) writes: >Um Nick, How does a 1,000 fold loss of Data transmission capacity, that >was fully booked, condense to only a 30% loss of Mission? ... By a combination of a lot of sweating on data compression and improved receiver hardware, plus some fairly drastic changes in operational plans, plus drastic cuts in some of the more imaging-intensive efforts. That 30% isn't across the board, it's heavily concentrated in the more data-intensive parts of the mission, notably the atmosphere imaging. (The moon flybys aren't getting hit all that badly, because while they are very imaging-intensive, they're also brief with long waiting periods in between, so they lend themselves to taping the images and then slowly dribbling the data back to Earth between encounters.) I'm sure the best possible face has been put on the numbers for PR use -- any number like that is mostly for PR anyway, since you can't weigh science results like that -- but if you aren't an aspiring Jupiter meterologist, the problem is, if not solved, at least under control. -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sat, 20 Mar 1993 04:38:00 GMT From: Henry Spencer Subject: Lunar Arctic, pressure, antifreeze (was Re: Lunar ice transport) Newsgroups: sci.space In article <1993Mar19.142635.1@fnalf.fnal.gov> higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes: >Remember Henry's assertion that the temperature is a constant 255 K >underground? That nice steady thermal environment is mighty >attractive. Note that that's at a depth of 1m. Our measurements go down only 2-3m (and go down that far at only one site -- it took until Apollo 16 to sort out the problems of drilling holes in the regolith, and then John Young had to trip over the damn cable, so our only deep data is from Apollo 17...), but it looks like the temperature rises at something like 1.3K/m. You might not have to bury the thing all that deeply to get above 0C. Of course, going down (say) 15m is still a *lot* more excavation... and lunar excavation is a pain, the regolith is just dust but it's packed down **HARD**. You'll also start hitting big rocks at some ill-defined depth where the regolith ends and mega-regolith begins. -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 20 Mar 1993 02:58 UT From: Ron Baalke Subject: Magellan Update - 03/19/93 Newsgroups: sci.space,sci.astro,alt.sci.planetary Forwarded from Doug Griffith, Magellan Project Manager MAGELLAN STATUS REPORT March 19, 1993 1. The Magellan spacecraft is operating normally, performing a desat (desaturation of the reaction wheels) on every orbit and a starcal (star calibration) every other orbit. The High Gain Antenna is kept pointed toward Earth (except during the starcal) in order to acquire gravity data, especially around periapsis. Engineering telemetry is being received at 1200 bps. 2. The Magellan Project continues to implement the plan to collocate 50 MESUR (Mars Enviromental Survey project) members on the second floor of Bldg. 230, while minimizing impact to MGN preparations for TEX (Transition Experiment) and LMGT (Lean Mean Gravity Team). About half of the offices being vacated by MGN team members have been cleared, and the remaining moves will be complete by March 31st. Significant amounts of excess paper have been eliminated, and unneeded equipment has been surplused. 3. Several members of the Magellan science team were in Houston, Texas, this week for the Lunar and Planetary Science Conference. An Exhibit of Magellan results was presented, as well as technical papers. 4. Magellan completed its 7000 orbit of Venus shortly before midnight (PST) on Tuesday. We are now 67 days from the end of Cycle-4 and the start of the Transition Experiment. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Don't ever take a fence /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | down until you know the |_____|/ |_|/ |_____|/ | reason it was put up. ------------------------------ Date: 20 Mar 1993 09:15:16 GMT From: Zdzislaw Meglicki Subject: Our Universe not a party Universe? Newsgroups: sci.astro,sci.space,sci.physics In article , neff@iaiowa.physics.uiowa.edu (John S. Neff) writes: |> In article rabjab@golem.ucsd.edu (Jeff Bytof) writes: |> >From: rabjab@golem.ucsd.edu (Jeff Bytof) |> >Subject: Our Universe not a party Universe? |> >Date: Fri, 19 Mar 1993 02:12:01 GMT |> >In article dpalmer@csulb.edu (Dave Palmer) writes: |> > |> >>Those of us who grew up reading science fiction have become comfortable |> >>with the idea of rapid space travel via some sort of "space warp." That |> >>is, a technology for warping space or passing through wormholes, |> >>hyperspace, or whatever. I think we've just tended to assume that someday |> >>we will discover how to do this. But what if no such mechanism is |> >>possible? Or, if it is, but requires impractical energies, or has some |> >>other practical limitation? [...] |> A practical problem, seldom covered in science fiction stories |> about traveling at near the speed of light, is the radiation hazard. |> If we assume v = 0.9c and N = 1 hydrogen atom per cc for an average |> density in interstellar space the flux of ~ 100 MeV protons will |> be about 2e10 per sq cm of effective area of spacecraft. Hardening |> equipment to work under such conditions will be a big challenge, and |> keeping people alive will be even more difficult. I strongly suspect that we're doomed never to try interstellar travel in our current form. If our civilisation is ever to spread it may happen in an altogether different way: durable, intelligent robots travelling from one star to another at pretty unimpressive speeds (but, what's 10,000 years for a machine in vacuum, the more so if it can switch itself off to save its power sources). We're just the "missing link", or, if you prefer, "cosmic larvae". -- Zdzislaw Gustav Meglicki, gustav@arp.anu.edu.au, Automated Reasoning Program - CISR, and Plasma Theory Group - RSPhysS, The Australian National University, G.P.O. Box 4, Canberra, A.C.T., 2601, Australia, fax: (Australia)-6-249-0747, tel: (Australia)-6-249-0158 ------------------------------ Date: Sat, 20 Mar 1993 03:15:30 GMT From: Cameron Randale Bass Subject: Predicting gravity wave quantization & Cosmic Noise Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary In article <1oe03gINNcl2@uwm.edu> markh@csd4.csd.uwm.edu (Mark) writes: >In article crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes: >> Not really wishing to start another discussion on what the 'speed' >> of gravity means, if the waves travelled instantaneously, how >> does one define or detect a 'wave'? > >I believe that the universe is closed. That means that all functions are >decomposeable into a series of harmonics with respect to the closed dimensions. >I believe that the metric has components at low frequencies that are residual >from the Big Bang. They will occur as standing waves, so the idea of wave >speed is utterly inappropriate. Ignoring the fact that you're talking about standing waves of tremendous spatial extent (and ignoring that wavespeed can be perfectly well defined in systems with standing waves), your coefficients are changing with time (since you apparently believe in some sort of 'Bang'). Have you worked out the havoc this is going to cause with your 'standing waves'? >Since there's closure in the spatial dimensions, these components will only >exist at discrete values of wavelength and frequency, which (doing a back of >the envelope calculation) comes out to something on the order of a millimeter >separation for wavelengths of 1 AU (wavelength^2 / universe radius). > >If the spacecraft are separated far enough (like by more than 1 AU) you could >detect these components because it's like you'll have a huge antenna detecting >them. Having more than one spacecraft is crucial in order to triangulate. Okay, we're bathed in such 'waves', right? At what amplitude, and how will it affect the spacecraft? With a wavepacket of limited temporal extent, you presumably see the 'whack'. What you're asking for is a constant vibration at all three satellites and the ground station. How does one distinguish this from 'noise'? And how in the blazes do you propose 'triangulating' a standing wave? What does that even mean? dale bass ------------------------------ Date: Sat, 20 Mar 1993 08:10:24 GMT From: Nick Szabo Subject: Space Station Redesign: Constellation Newsgroups: sci.space Let's step back and consider the functionality we want: [1] microgravity/vacuum process research [2] life sciences research (adaptation to space) [3] spacecraft maintenence The old NASA approach, explified by Shuttle and SSF, was to centralize functionality. These projects failed to meet their targets by a wide margin: the military and commercial users took most of their payloads off Shuttle after wasting much effort to tie their payloads to it, and SSF has failed in a jumble of disorganization and miscommunication. Over $50 billion has been spent on these two projects with no reduction in launch costs and no improvement in commercial space industrialization. Meanwhile, military and commercial users have come up with a superior strategy for space development: the constellation. Firstly, different functions are broken down into different constellations placed in the optimal orbit for each function: thus we have the GPS/Navstar constellation in 12-hour orbits, comsats in Clarke and Molniya orbits, etc. Secondly, the task is distributed amongst several spacecraft in a constellation, providing for redundancy and full coverage where needed. SSF's 3 main functions require quite different environments and are also prime candidates for constellization. [1] We have the makings of a materials processing constellation now: COMET and Mir for long-duration flights, Shuttle/Spacelab for short-duration flights. The best strategy for this area is inexpensive, incremental improvement: installation of U.S. facilities on Mir, Shuttle/Mir linkup, and transition from Shuttle/Spacelab to a much less expensive SSTO/Spacehab/COMET or SSTO/SIF/COMET. We might also expand the research program to take advantage of interesting space environments, eg the high-radiation Van Allen belt or gas/plasma gradients in comet tails. The COMET system can be much more easily retrofitted for these tasks, where a station is too large to affordably launch beyond LEO. [2] We need to study life sciences not just in microgravity, but also in lunar and Martian gravities, and in the radiation environments of deep space instead of the protected shelter of LEO. This is a very long-term, low-priority project, since astronauts will have little practical use in the space program until costs come down orders of magnitude. Furthermore, using astronauts severely restricts the scope of the investigation, and the sample size. So I propose LabRatSat, a constellation tether-bolo satellites that test out various levels of gravity in super-Van-Allen-Belt orbits that are representative of the radiation environment encountered on Earth-Moon, Earth-Mars, Earth-asteroid, etc. trips. The miniaturized life support machinery might be operated real-time from earth thru a VR interface. AFter several orbital missions have been flown, follow-ons can act as LDEFs on the lunar and Martian surface, testing out the actual environment at low cost before $billions are spent on astronauts. [3] By far the largest market for spacecraft servicing is in Clarke orbit. I propose a fleet of small teleoperated robots. Ground engineers can practice their skills on the many defunct satellites in Clarke and super-Clarke orbit before trying them out on real cases. Once in place, robots can pry stuck solar arrays and antennas, attach solar battery power packs, inject fuel, etc. Once the fleet is working, it can be spun off to commercial company(s) who can work with the comsat companies to develop comsat replaceable module standards. By applying the successful constellation strategy, and getting rid of the failed centralized strategy of Shuttle and SSF, we have radically improved the capability of the program while greatly cutting its cost. For a fraction of SSF's pricetag, we can fix satellites where the satellites are, we can study life's adaptation to a larger & more representative variety of space environments, and we can do microgravity and vacuum research inexpensively and, if needed, in special-purpose orbits. In this constellation strategy lie also the seeds of two potential U.S. export industries: affordable space materials processing and satellite servicing. The key is lowering the cost of capability to the point where the commercial market is large and profitable without further NASA intervention. The centralized-station strategy has demonstrated just the opposite, cost hikes and capability cuts, and has thus demonstrated its inability to foster new space industries. N.B., we can apply the constellation strategy to SEI as well, greatly cutting its cost and increasing its functionality. MESUR and Artemis are two good examples of this; more ambitiously we can set up a network of native propellant plants on Mars that can be used to fuel planet-wide rover/ballistic hopper prospecting and sample return. The descendants of LabRatSat's technology can be used as a Mars surface LDEF and to test out closed-ecology greenhouses on Mars at low cost. The decentralized strategy also allows concurrent exploration & development of the moon, asteroids, Jupiter-family comets and Mars. We can pick favorites based on actual discoveries when we make them, instead of being forced to make an initial choice, and putting all our eggs in one very expensive planetary basket which may turn out to be barren. -- Nick Szabo szabo@techboook.com ------------------------------ Date: Fri, 19 Mar 93 23:41:28 PST From: Mark Robert Thorson Subject: SR-71 Maiden Science Flight Newsgroups: sci.space > The SR-71 can take measurements across a wider area at that > height, it can also take measurments in day, night and terminator > between day/night all in 1 flight, i.e. within a short period of > time. This wide sample space may provide useful information beyond > what a balloon's sample space would be. But what if you used TWO balloons, or maybe three. That would solve the sample space problem at much lower cost. ------------------------------ Date: Sat, 20 Mar 1993 04:28:11 GMT From: Henry Spencer Subject: SSTO: A Spaceship for the rest of us Newsgroups: sci.space In article steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes: > Second, and more serious, I quoted LOX at five **CENTS** a pound, not > five dollars a pound. > >Got a source for that number? You can't get drinking water for 5c/lb >in most places! ... The source is Max Hunter, who knows more than a little about launchers and launcher economics... For those unfamiliar with the name, Hunter was chief engineer for Thor, which eventually became Delta, and is the father of the current SSTO project. Much of my technical-issues writeup was based on his "The SSX: SpaceShip Experimental", revised draft, 11 March 1989. (Please don't ask where you can get a copy -- I don't know.) -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sat, 20 Mar 1993 04:20:16 GMT From: Bruce Dunn Subject: Water Simulations Newsgroups: sci.space > Henry Spencer writes: > > There are two things really wrong with the water-tank simulation of free > fall. One is that you are lying in your suit rather than floating in it. > The other is the more obvious issue: the water has viscosity. I once again offer my suggestion of a neutral buoyancy simulator using pentane rather than water for buoyancy. Pentane has only a small fraction of the viscosity of water. There are obvious problems with operating such a facility (previously hashed over in this group), but I am not convinced that there are any show stoppers. Yesterday I spent several minutes in semi-darkness in 110 feet of water at 8 C, with my body tissues rapidly loading with dissolved nitrogen as I breathed air from a system which inherently has a number of single point failure modes. I enjoyed it thoroughly - I was sport diving on SCUBA. However, although this was a routine dive I probably would have been a lot safer if I was in a spacesuit submerged in 10 feet of pentane, with safety personnel watching every move and standing by to haul me out at the first sign of trouble. -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ Date: Sat, 20 Mar 1993 07:27:31 GMT From: "Richard A. Schumacher" Subject: Why use AC at 20kHz for SSF Power? Newsgroups: sci.space >One of the most frequent complaints here against NASA is that >they don't consider new technologies that might lower costs >in the long run and don't experiment with different concepts. >Yet, when they do and it doesn't work out they are chastised >(often by the same people) for wasting money when they could >have been using old and tried technology, and using the >magic of 20-20 hindsight it becomes "obvious" that the >new concept tried wouldn't work. >Pah! The problem is that NASA hasn't had decent experimental technology programs for years. They attempt to turn all new technology into an operational system all at once without allowing for necessary development time. Notice how well that worked with the shuttle. The twin points are: if you want to build an operational system with minimum cost and risk, use existing technology. If you want to develop new technologies, run experimental programs. If you're serious about what you're doing, you do both in tandem. One should not have to figure out how to dry lumber and make nails while building the house. >Those [scientific] instruments are handbuilt at no small expense. Thank you for making my point! Handbuilt, unique, non-standard stuff, like 20 kHz power systems and things to plug into them, are expensive. 10 years from now, after 10 years of development effort, 20 kHz power systems might be cheap, reliable and the right choice. For something that was originally intended to fly last year, they're not. Go out and buy something else. ------------------------------ End of Space Digest Volume 16 : Issue 345 ------------------------------