Subject: Space-tech Digest #90 Contents: Dani Eder Getting stuff off the moon Bill Trost Re: Getting stuff off the moon Steve Abrams International Space University 1992 ? Beaufait ISU CAMPUS Nick Szabo Re: lunar volatiles Paul Dietz Re: lunar volatiles Phil Fraering Re: lunar volatiles ------------------------------------------------------------ Date: Mon, 9 Dec 91 10:40:13 CST From: eder@hsvaic.boeing.com (Dani Eder) To: space-tech@cs.cmu.edu Subject: Getting stuff off the moon Summary: You don't need to use a rocket to get stuff off the Moon, mechanical catapults will suffice! Assume a crater about 16 km across. On one rim you find a big rock (say 1000 tons). Tie a big cable to this rock. Lunar gravity is 1.62 m/s^2, so the rock makes a force of 1.62MN. Using a strength of 250,000 psi, the rope has a diameter 3.5 cm. Let the rock fall 450 m to the bottom of the crater (note: an anchor on the floor of the crater may be required to guide the rock down at an angle if a vertical cliff high enough is not available, but there are a lot of craters on the Moon). The cable is wound on a horizontal axle mounted on the top lip of the crater. Attached to the same axle is a large wheel with a diameter 36x as large as the axle. attached to the wheel is a lighter rope, designed to wind onto the wheel as the rock falls and unwinds the thick cable. The light rope is stretched across the crater to the other side, 16 km away. There it is tied to a payload sitting on two upward sloping rails. When the big rock is dropped, the light rope tugs on the payload at several g's sideways (6 g's neglecting the mass of the rope and axle bearing friction) The rails give the payload an initial upward velocity, to keep it from slamming into the opposite crater wall by the time it gets there. At six gees, over a distance of 16 km, you end up with 1385 m/s hortizontal velocity. If you start with a 20 km crater and an axle ratio fo 40 rather than 36, you get 1610 m/s. Orbital velocity for the Moon is around 1678 m/s. Now, the rope in the latter case has about as much mass as the payload, say 10 tons each. The 20 tons of light rope plus payload are being accelerated at 6 gees, so the force is 120 tons. Going through an axle ratio of 50 makes this 6000 tons, so our original rock needs to be more like 10,000 tons in mass. Then the big rope runs about 10 tons also. With anchors and axle hardware, we are looking at 40-50 tons of equipment that can throw 10 tons to orbit at a shot. Re-setting is done by an electric motor that cranks the big rock back up by unwinding the light rope. If we have a 70% efficient cranking machine, then a 100 kW power supply (massing 2 tons if photovoltaic), can power 10 launches per month. If we have 20 tons of power supply then we can power 100 launches per month, or 1000 tons of cargo for an initial mass investment of around 70 tons. The annual mass return ratio is then 170:1. Dani ------------------------------ Date: Mon, 9 Dec 91 11:01 PST From: trost@reed.edu (Bill Trost) To: Dani Eder Subject: Getting stuff off the moon cc: space-tech@cs.cmu.edu Dani Edir writes: Summary: You don't need to use a rocket to get stuff off the Moon, mechanical catapults will suffice ! Assume a crater about 16 km across. On one rim you find a big rock (say 1000 tons). Tie a big cable to this rock.... Ah yes, the Wile E. Coyote launch system.... :-) I scribbled out the basic work for this a while ago, but have since lost the envelope I scribbled it on. I do remember, however, that acheiving lunar escape velocity (as opposed to orbital velocity) was going to take a *really big* rock. Someone else should probably go over the computations -- Dani's work had much better detail than mine (and looked easier -- hazards of getting my degree in math...). Also, no one has mentioned centrifugal launchers. The first I saw of this was in something by Jerry Pournelle. Essentially, you take a big spinning disk, slightly tilted. You set your payload on the middle of the disk and slowly let it out to the edge. Then you let go of the payload, and it gets flinged off into space. Actually, I think Jerry Pournelle was proposing this more as a means of launching regolith than for actual spacecraft launches. At the very least, you'd probably need a dizzy-proof payload, but again, someone needs to do the computations. ------------------------------ Date: Tue, 10 Dec 91 18:48:43 EST From: abrams%cfa0@harvard.harvard.edu (Steve Abrams) To: space-tech@daisy.learning.cs.cmu.edu Subject: International Space University 1992 Sender: mnr@DAISY.LEARNING.CS.CMU.EDU APPLICATIONS FOR THE INTERNATIONAL SPACE UNIVERSITY 1992 SUMMER SESSION, TO BE HELD IN KITAKYUSHU, JAPAN, 16 JUNE - 26 AUGUST ARE NOW AVAILABLE UPON E-MAIL REQUEST. The International Space University, founded in 1987, provides graduate-level students and aerospace professionals an annual summer program embracing nine academic areas in a multidisciplinary approach to space studies. The intensive summer course, with over 185 hours of lectures and 125 hours of design project work, compresses a full year of study into ten weeks. The ISU program has graduated 494 students from 43 countries in four sessions held in four different cities in the world (Cambridge, USA; Strasbourg, FRANCE; Toronto, CANADA; Toulouse, FRANCE). Next summer, during the International Space Year 1992, the host city will be the southern city of Kitakyushu in JAPAN. The core curriculum of ISU includes series of lectures in each of eight departments: Space Architecture, Space Business & Management, Space Engineering, Space Life Sciences, Space Policy & Law, Space Physical Sciences, Space Resources & Manufacturing, and Satellite Applications. A new program, Space Humanities, will also include core lectures. These departments include Faculty and Visiting Lecturers who are internationally-recognized experts in their fields. All students attend the core curriculum lectures of all departments; this provides the common set of knowledge utilized by the students in the second-half multidisciplinary seminar program (more focused than the core program) and the design projects. The seminar program includes lectures on topics of overlapping interest in two or more departments. Approximately 75 visiting lecturers contribute to the seminar program. In addition to the scheduled lectures and cultural activities, students next summer will work on one of two design projects: the ISUNET or the Space Solar Power Program (SSPP). The design projects complement the academic lectures by providing a venue for the students to apply what they have learned, as well as the skills they bring to the session, in a multicultural setting. The ISUNET design project will involve the design of a global telecommunications and data network relating to ISU's plan to establish a Permanent Campus System in the 1995-6 timeframe. This System will include a Central Campus (the one-year program of which will award a Masters in Space Studies degree; this site for this Campus is planned to be announced around the end of August next year), several Affiliate Campuses, and - eventually - several Advanced Campuses. The design project will use these plans of ISU as a background for the establishment of this network. Although the design project is an academic exercise, past experience has shown that many innovative ideas are generated by the dynamic synergy between faculty and students; as such, it is expected that ISU will implement many of the results of this project. Connecting the many campuses and other research facilities together via voice, fax, data, and video links (both space-based and terrestrial), in support of ISU's administrative and academic needs and goals, will provide one focus for this design project. Development of an all-electronic, full-text & graphics Space Library and the role of the information sciences in higher education will provide other foci. Evaluating anticipated user needs, both internally to ISU and externally with government agencies, academia, and industry, will round out the program. The Space Solar Power Program design project will give students the opportunity to develop a strategic plan for the creation and development of a multinational space power consortium. Students will investigate potential means of solar power generation in space and recommend an optimum course of action, with alternatives, to utilize these energy resources both in space and on earth. Topics of interest will include the development of a business plan, study of the legal ramifications, review of previous technology development, engineering problems inherent in projects of this scale, evaluation of environmental impact, and laboratory demonstrations of requisite technology. In addition to the arduous academic program, the ISU summer session features a series of multicultural events, designed to facilitate the students' learning about the world outside their native lands, and other events that will expose the students to the way of life in the host country, Japan. Cultural Nights feature specific countries and regions of the world and can include ethnic meals, visual presentations, native entertainment, and social interaction to relax from the day's studies. Talent Night will allow students to express themselves creatively. A four-day Alumni Visit by previous graduates of ISU will promote the networking of future space leaders. Midway through the session, a Field Trip will expose students to the space industry in Japan and provide a brief respite from the program. Applicants to the ISU program must have a Bachelor's degree from an accredited university and a general understanding of the disciplines represented in the ISU curriculum. They must either have "graduate student" status (either holding a Master's or Doctoral degree or currently enrolled or accepted in a graduate program) or professional experience in industry, academia, or government following the successful completion of a bachelor's degree (or equivalent). All applicants must have a demonstrated proficiency in the English language (the language of operation for ISU); native English-speakers must demonstrate proficiency in a second language. Selection criteria for students include: excellence in their chosen field, leadership, internationalism, commitment, and experience. ***** Applications are due by 15 January 1992 ***** Applications are available via e-mail request to: abrams@cfa.harvard.edu. Allow 2-3 weeks for delivery outside North America. If you have any questions concerning ISU or the application process, please contact Steve Abrams at: abrams@cfa.harvard.edu or call ISU at +1.617.354.1987. This announcement is submitted due to the high likeliehood that subscribers to Space Tech would be interested in a means through which they could apply their technical know-how, and gain something in the process... Steve ------------------------------ Date: Wed, 11 Dec 91 15:09 EDT From: BEAUFAIT%CEBAFVAX.BITNET@BITNET.CC.CMU.EDU Subject: ISU CAMPUS To: space-tech@DAISY.LEARNING.CS.CMU.EDU X-Original-To: space-tech@DAISY.LEARNING.CS.CMU.EDU, BEAUFAIT WHO/WHERE COULD I GO TO GET INFO ON GETTING MY COLLEGE SIGNED UP AS AN AFFILIATE D CAMPUS? IS IT TO LATE TO PUT IN A PROPOSAL FOR THE CENTRAL CAMPUS. ------------------------------ From: sequent!techbook.com!szabo@uunet.UU.NET (Nick Szabo) Subject: Re: lunar volatiles To: space-tech@cs.cmu.edu Date: Sun, 8 Dec 91 21:03:14 PST X-Mailer: ELM [version 2.4dev PL32] Some assumptions occur in the discussion on lunar volatiles, and engines to make use of them, that need to be questioned: i) Isp is the most important issue. Where native fuel is abundant and easily extracted, and the fuel tank comes from Earth, the mass of the tank is a more important variable than the mass of fuel used. For this reason, nuclear-steam is better than either chemical hydrogen/oxygen or nuclear-hydrogen for returning volatiles from comets to Earth orbit, for example. Hydrogen needs to be stored in a large pressure vessel brought up from Earth, but ice needs only a sealing bag and net to distribute engine and gravity forces. Furthermore, in most cases the driving mass budget variable is extraction equipment, not transport vehicle. The mass of equipment brought up from Earth for H, Al, etc. extraction dominate schemes that require such heavy processing equipment. Discussions focusing on rocket engine issues often miss the most important factors. ii) The Moon lives in a vacuum. :-) The Moon will be one part of a larger solar-system economy, exporting in order to pay for itself and importing what it needs. It is not a given that the Moon will play the first or most important role in native materials. As one counter-example, it is probable that there are a great abundance of comets in the inner solar system. Several already discovered short-period comets, for example P/du Toit-Hartley and P/Finley, can be mined with mass-payback ratios of 200 or more, far superior to that of lunar native fuel schemes and with much less equipment mass launched from Earth. It is probable that many objects now considered asteroids contain sufficient ice or water of hydration to be similarly mined, or that smaller comets exist in better orbits, giving MPR's above 1,000, but this requires further exploration. Design judgements, especially the assumption that volatiles will be rare/expensive and that equipment has to operate in a gravity field, are heavily skewed by the focusing solely on the Moon. Now to specific comments: >[ice] is likely contaminated with a wide range of impurities, >including hydrocarbons, alcohols, clathrates of various kinds, >sulfurous compounds, halogenated compounds, and so on. So, any ice >processing system is going to have to be able to purify the resulting >water. Can a thermal engine be driven off impure, or at least mixed, volatiles? Could some kinds of additives reduce the oxidizing problem? Paul mentions a mixture of methanol and water. What chemical(s) would maximize the water mass fraction while minizimizing extraction equipment mass for a non-oxidizing mixture? > Note, however, a nasty design complication: both water and CO2 become > oxidizing agents at high temperatures, which presents materials problems > for a nuclear-thermal rocket. Hydrogen or hydrocarbons are better here too. At what temperatures does this become a problem? The Powell/Ludweig particle bed reactor proposed for nuclear-steam operates at 1200C, delivering and Isp of 235 for water (reasonable where native water is abundant). szabo@techbook.COM ...!{tektronix!nosun,uunet}techbook!szabo Public Access UNIX at (503) 644-8135 (1200/2400) Voice: +1 503 646-8257 Public Access User --- Not affiliated with TECHbooks ------------------------------ Date: Mon, 9 Dec 91 11:35:37 EST From: dietz@cs.rochester.edu To: sequent!techbook.com!szabo@uunet.UU.NET Subject: Re: lunar volatiles Cc: space-tech@cs.cmu.edu >[ice] is likely contaminated with a wide range of impurities, >including hydrocarbons, alcohols, clathrates of various kinds, >sulfurous compounds, halogenated compounds, and so on. So, any ice >processing system is going to have to be able to purify the resulting >water. Can a thermal engine be driven off impure, or at least mixed, volatiles? Could some kinds of additives reduce the oxidizing problem? Paul mentions a mixture of methanol and water. What chemical(s) would maximize the water mass fraction while minizimizing extraction equipment mass for a non-oxidizing mixture? I would worry about driving a thermal engine off of impure mixtures. For example, chlorinated compounds react with hot steam to form hydrogen chloride. Sulfur can form hydrogen sulfide. Could be corrosive. Perhaps additives can neutralize these. I suspect it would not be that hard to purify the water, however. Distillation, reverse osmosis, or freezing are all possibilities. Details would depend on just what's in the ice, which I don't think we have a good handle on. It might be possible to purify slightly contaminated water by irradiation. This would create reactive radicals that could oxidize trace organic contaminants. There would be a great deal of low cost radiation available if the process is being powered by a nuclear reactor. I suspect the lowest mass additive to render water less oxidizing would be methane (assuming hydrogen is ruled out). Methane can be stored with ice as the clathrate, at sufficiently low temperature. Extremely fine particles of generic organic glop might also work, if the particles do not interfere with pumps or valves and can be kept in suspension (and if they don't contain too much in the way of corrosive impurities). Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Mon, 9 Dec 1991 22:57:49 -0600 From: Fraering Philip G To: space-tech@CS.CMU.EDU, szabo@techbook.com Subject: Re: lunar volatiles Hmmm... did you see my comments earlier about oxygen ion rockets? Phil ------------------------------ End of Space-tech Digest #90 *******************