Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Thu, 8 Feb 90 01:34:57 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 8 Feb 90 01:34:36 -0500 (EST) Subject: SPACE Digest V11 #18 SPACE Digest Volume 11 : Issue 18 Today's Topics: Re: More Info On SSX Galileo Update - 02/07/90 Re: SSX Re: Spacecraft drives and fuel efficiency Re: Galileo Update - 02/06/90 (Forwarded) MOS 1-B Launched Gravity Assist Mechanism Re: More Info On SSX ---------------------------------------------------------------------- Date: 7 Feb 90 12:24:32 GMT From: ispi!jbayer@rutgers.edu (Jonathan Bayer) Subject: Re: More Info On SSX carroll@m.cs.uiuc.edu writes: >/* Written 6:14 pm Feb 5, 1990 by larry@omews10.intel.com in m.cs.uiuc.edu:sci.space */ >/* ---------- "More Info On SSX" ---------- */ [ deleted ] >The anticipated cost of >each vehicle is around $30 million, yielding launch costs >of about $50 per pound of payload in Low Earth Orbit. >/* End of text from m.cs.uiuc.edu:sci.space */ >Forgive my math, but I get >$30,000,000 / 20,000 lb = $1500/lb, not $50. >For a 9,000 lb payload, it's $3333/lb. Where did you get $50/lb from? >For a 20,000 lb payload, and $50/lb, the vehicle must cost only $1million. Well, if you only use it once then your numbers are correct. On the other hand, if you assume that it will be used 100 times then the cost works out as follows: $30,000,000 / 20,000 lb / 100 trips = $ 15/lb This is for the cost of the vehicle alone. The rest of the cost is now fuel and labor costs. JB -- Jonathan Bayer Intelligent Software Products, Inc. (201) 245-5922 500 Oakwood Ave. jbayer@ispi.COM Roselle Park, NJ 07204 ------------------------------ Date: 7 Feb 90 20:21:47 GMT From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@tut.cis.ohio-state.edu (Ron Baalke) Subject: Galileo Update - 02/07/90 GALILEO MISSION STATUS February 7, 1990 Today the Galileo spacecraft is 29.4 million miles from Earth; round-trip light time is 5 minutes 16 seconds. It has rolled up almost 181 million of the 185 million miles around its orbit from launch last October to the Venus flyby, which occurs Friday night (a minute before 10 p.m. PST, or about 1 a.m. EST). Heliocentric velocity has now reached about 83,000 mph. The Venus gravity-assist flyby will bring the spacecraft about 10,000 miles above the cloud-tops, 41 degrees south of the planet's equator. Galileo will cross behind Venus, increase its velocity by about 5,000 mph, and take up a different, slightly larger solar orbit which comes within 65 million miles of the Sun on February 25 and then curves out to fly by Earth in December for its second gravity assist at a 600-mile altitude. During the Venus flyby, the spacecraft will record about 80 images and many other scientific observations for playback in late October when the telecommunications link can support the 7.68-kilobit science data rate. The spacecraft continues in excellent health; the power margin and spacecraft temperatures are as expected. Galileo is in normal cruise mode, with part of the spacecraft despun and the rest spinning at 3.15 rpm. The telemetry rate is 1200 bits per second, radiating from low-gain antenna No. 2. The spacecraft attitude sun point angle is at 2.6 degrees. The first part of the Venus flyby operational sequence was transmitted up yesterday (and is now active aboard Galileo); the rest is to be sent up tomorrow. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: Wed, 7 Feb 90 21:10:47 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: SSX I have a 33-page paper entitled THE SSX SPACESHIP, EXPERIMENTAL - - - by Maxwell W. Hunter 15 March 1988 Updated 11 March 1989 There's also a mailing address. I suspect Mr. Hunter would not appreciate suddenly getting hundreds of requests for free copies, so I'm not posting it. If anyone's really interested, I could send the address, and that person could serve as a liaison. There are many figures and tables in the paper, but perhaps at least the text part could be put in the archives. The paper presents at least three concepts: - The philosophy of rocket design and launch services. - A specific proposal for an experimental design project. - Flames about current design approaches, policies, and organizations. This paper is amazing in that it is almost a complete rewrite of the current school of though on rocket design. Many ideas are presented that go strongly against current thinking. Among the concepts presented: - Rockets are highly efficient because almost all of the chemical energy of the fuel and oxidizer goes into kinetic energy of the rocket. - Airbreathing rockets are not much good because too much of the energy goes into working against drag (no math to support this). - In a "properly designed" rocket, most of the cost of a launch is the cost of the fuel, and oxygen, being cheaper than hydrogen, adds little to the cost of the launch. - Vehicle weight (other than payload) is mostly a function of fuel tank weight, which is (linearly?) proportional to the energy density of the fuel. Therefore, propellant density times Isp squared is a much better index of desirability of a fuel than is Isp alone. This makes heavy hydrocarbons + oxygen a better choice than hydrogen + oxygen. - Launch costs (fuel cost multiplied by 3) should eventually drop to ~$10 per pound of payload. - Components should be built with plenty of design margin, for high reliability (the ALS approach). Rockets should be reusable. They should not require thorough checking between launches. - Vehicles should be built purely for test purposes (the NASP philosophy). - SSX should use technology developed for NASP. - SSX should be made with many engines (aerospike design) so that the failure of a few engines does not prevent safe landing. - Being reusable, SSX can be put through progressively higher test flights, until orbit is achieved. - SSX can be flown with or without humans aboard. - An effort should be made to minimize the number of people participating in a mission, to save labor costs. - Design programs should be fast. Comments: It seems to be the general custom in research that when an assertion is made which closely matches the existing consensus, the research community is generally willing to accept it based on simple arguments. When a strongly contradictory assertion is made, however, much more rigorous proof is required before it is accepted. This paper makes several claims that go very much against current thinking in rocket design. I feel that the arguments to support some of these views are not correspondingly rigorous. I would like to see a more rigid mathematical analysis of these points. I also find some of the graphs hard to interpret, such as the one which plots empty weight/payload weight as a function of propellant cost/payload weight. This is not to say that I have any specific doubts about the ultimate viability of SSX. Many of the ideas presented seem very sensible. I just don't think that this particular paper ties everything together in such a way that it presents a truly convincing argument that SSX is the best way to go. Of course, I may have misunderstood some of the paper, and there may be more comprehensive papers that I have not seen. If (as someone posted) the government has indeed decided to fund SSX research, I hope that the first part of the money will go toward making a more complete analysis, and a more specific presentation of the design proposal. This would be consistent with the usual approach for government-funded research. (As usual, these are my own opinions.) John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 7 Feb 90 16:55:19 GMT From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Spacecraft drives and fuel efficiency In article <1990Feb7.024413.9969@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes: >>>... anti-matter sounds as if it involves technical >>>problems that make fusion engines look like tinker toys... > >>The fun part is, it may actually be the other way around! > >Really? But we already have a proven method of releasing unlimited >amounts of fusion energy -- hydrogen bombs. Dyson designed an H-bomb >propelled interstellar spacecraft years ago. It had low acceleration, >but it could reach .01 c. I believe it used hydrogen bombs pushing >against a copper plate, which was cooled by radiation. A magnetic >nozzle scheme might have better performance. If we want to propel something with about the size and mass of Chicago, Dyson's scheme works pretty nicely (although 0.01c is only marginally viable as an interstellar velocity). Unfortunately, it does not scale down too well. Dyson was figuring on 100MT bombs, as I recall. Smaller nuclear bombs are an expensive source of energy; very small ones are very expensive. When you get down into the range of interest for current in-space propulsion, bombs basically aren't practical at all unless you have a better way of igniting the reaction. Which gets you back to the problems of fusion, complicated by severe weight constraints. A spacecraft probably cannot use laser-ignited fusion unless lasers improve vastly -- they are too heavy. That's why Daedalus used electron beams, which solves that problem at the expense of creating others. Actually, a little bit of antimatter makes a dandy igniter for a fusion reaction...! -- SVR4: every feature you ever | Henry Spencer at U of Toronto Zoology wanted, and plenty you didn't.| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 7 Feb 90 21:22:12 GMT From: binkley@boulder.colorado.edu (Jon Binkley) Subject: Re: Galileo Update - 02/06/90 (Forwarded) In article <47686@lll-winken.LLNL.GOV> loren@sunlight.UUCP (Loren Petrich) writes: >[Galileo's main antenna] was not >designed to get too close to the Sun; they had to install some >insulation, and they have to keep the main antenna closed, or else it >would disintegrate. When the craft makes its second Earth flyby, will it come close enough to the sun that they have to cover up the antenna again, or will it remain unfurlled for the rest of its journey? -Jon ------------------------------ Date: 7 Feb 90 22:44:09 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: MOS 1-B Launched [This message is posted for Yoshiro Yamada of the Yokohama Science Center. -PEY] * MOS-1b Launched * Marine Observation Satellite 1-b (MOS-1b) was successfully launched from Tanegashima Space Center at 10:33:00 JST (UT+9h) on February 7, by the H-1 rocket. All separation phases for MOS-1b, DEBUT (Deployable Boom and Umbrella Test) and JAS-1b (Japan Amateur Satellite-1b) were confirmed. After the launch, the three payloads were nicknamed as follows: MOS-1B MOMO-1b (MOMO means peach in Japanese) DEBUT ORIZURU (ORIZURU means crane shaped by folding paper in Japanese) JAS-1b FUJI-2 (FUJI has two meanings in Japanese: Mt. Fuji and wisteria) Missions: MOS-1b o Continue overall earth observations by Multi-spectrum Electronic Self- a scanning Radio-meter, Visible and Thermal Infrared Radiometer, Microwave Scanning Radiometer and Data Collection System. o Establish earth observation satellite operation technology including two satellite parallel operation. o Establish sun-synchronous orbit injection technology by H-1 launch vehicle. Piggy Back Payloads DEBUT o Deployable Boom and Umbrella Test (DEBUT) Satellite is the payload which performs function verification experiments in a space environment on a boom mechanism capable of being extended/retracted and an aerodynamic umbrella capable of being opened/closed. JAS-1b o JAS-1b (Japan Amateur Satellite-1b) is a satellite which facilitates worldwide satellite communications by amateur radio. The launch of JAS-1b enables amateur radio operators to learn about space science and satellites, also to understand space communication. JAS-1b will become the successor of JAS-1/Fuji-OSCAR 12, the Japan's first amateur satellite launched in 1986. Orbit MOS-1b Altitude approx. 909km Inclination approx. 99deg Configuration Box type attached with cantilever type solar paddle: main body 1.26x1.48x2.40(m) solar paddle 2.00x5.28(m) Weight approx. 740kg (at launch) Mission life 2 years DEBUT Altitude elliptical approx. 900x1600(km) Inclination approx. 99deg Configuration stored: 400mm in diameter(26-side polyhedron) 470mm in length (structure+boom+ aerodynamic umbrella) Weight 50+/-1 kg Power Subsystem Battery: Lithium battery (capacity 95 Ah) Design Service Life approx. 10 days (due to life of the internal primary battery) JAS-1b Altitude elliptical approx. 900x1600(km) Inclination approx. 99deg Configuration 440mm in diameter. 470mm in length Weight approx. 50kg (Sources: NASDA Information for Press and personal communication) ------------------------------ Date: 7 Feb 90 13:38:25 GMT From: mcsun!ukc!axion!axion.bt.co.uk!apengell@uunet.uu.net (alan pengelly) Subject: Gravity Assist Mechanism Here in the UK we recently had a couple of TV programs summarise the VOYAGER missions. Firstly we would like to say to all those at NASA 'well done'. The whole thing has been quite awe inspiring. But it also gave a couple of computer scientists a problem. We thought we knew all about gravity assist unitl we actually sat down and tried to work out the mechanism involved. We have been arguing ever since. We have two schools of thought. 1) Angular momentum is transferred from the planet too the spacecraft. The increased velocity of the spacecraft after the encounter is at the expense of the planets angular momentum, so it rotates more slowly. 2) It is the kinetic energy of the planet that it transferred. Thus the planets orbital period increases ( but then surely the planet would adopt an orbit closer to the sun?) Is there anybody out there that has a detailed understanding of gravity assist? We would greatly appreciate some enlightenment of this subject. Thanks in advance Alan Pengelly ------------------------------ Date: 7 Feb 90 16:43:46 GMT From: zaphod.mps.ohio-state.edu!samsung!umich!ox.com!itivax!vax3!aws@tut.cis.ohio-state.edu (Allen W. Sherzer) Subject: Re: More Info On SSX In article <1990Feb7.143516.14548@eplrx7.uucp> leipold@eplrx7.UUCP (Walt Leipold) writes: >>The anticipated cost of each vehicle is around $30 million,... >Do you seriously believe that you can build a reusable space vehicle >for less than a quarter of the cost of a 747? Why not? On the other hand, suppose they are off by a factor or four. In that case, it costs just as much as a 747. Still a good deal. >If the gov't is going to >be a customer, you probably won't even be able to meet the payroll of >your QA dept for $30M/vehicle... Not if HR2674 passes. Another interesting thing about SSX is the funding source: SDIO. This is a good sign IMHO because they more than anybody else in the government needs low cost to LEO. Interesting side note: a congressional aid I spoke with recently said that SDIO is so pleased with their first commercial launch that they plan to use commercial launch services from now on. Allen ---------------------------------------------------------------------------- | Allen W. Sherzer | Cthulhu for President - | | aws@iti.org | If you're tired of choosing the LESSER of 2 evils | ---------------------------------------------------------------------------- ------------------------------ End of SPACE Digest V11 #18 *******************