Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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 ; Tue, 14 May 91 02:35:54 -0400 (EDT) Message-ID: <4c=sJ5S00WBwA4QE5f@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 14 May 91 02:35:49 -0400 (EDT) Subject: SPACE Digest V13 #547 SPACE Digest Volume 13 : Issue 547 Today's Topics: Please advise on a telescope for children Re: SPACE Digest V13 #516 Re: Advancing Launch Technology Re: Why the space station?y Re: Launch Costs Honking at cyclists... Pegasus/SMEX/-Alive and Will Re: Launch Costs XXIV -- Wright Bros. Flyer to carry tanks to Kuwait! Systems Analysis Office created in line with Augustine Report (Forwarded) Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 13 May 91 20:26:17 GMT From: agate!linus!think.com!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!sunc!heinlein!umesh@ucbvax.Berkeley.EDU (Umesh Thakkar) Subject: Please advise on a telescope for children hi, I am interested in getting a telescope for my friends (aged: 8-12), and I would like some recommendations. I decided to buy one for them after watching the first episode of _The Astronomers_, a PBS series. This telescope will be used overseas, and so it must be very durable and easy to use. It must, also, be inexpensive so that I may be able to afford to buy it. Please email. Thank you in advance. umesh ------------------------------ Date: 13 May 91 21:12:49 GMT From: mintaka!ogicse!sequent!muncher.sequent.com!szabo@bloom-beacon.mit.edu Subject: Re: SPACE Digest V13 #516 In article <28875@hydra.gatech.EDU> ccoprmd@prism.gatech.EDU (Matthew DeLuca) writes: [somebody writes, lost attributon sorry:] >>Conclusion; yes, it could significantly alter the timetable for space >>development / commercialization. > >I don't see how your conclusion follows, myself. We do not have the >booster capacity, booster reliability, manned spaceflight experience, >or telerobotic capability to start exploiting asteroids in the next >few years, and I doubt it will be all ready to go by the end of the >decade, either. We really aren't in *that* big of a rush to get the >information. Asteroid and comet exploration makes a _big_ difference in the timetable. To see one of the reasons why, let's take a little side-trip into orbital mechanics. About the mid-1960's, the space explorers started realizing that we could use planets themselves to gain or lose large amounts of orbital energy by gravity assist around planets and Moons. The basic principle is, velocity in equals velocity out, but the _direction_ can change to any direction we want. This is limited by the mass and density of the planet itself. _Very_ roughly, you can't change the velocity vector by more than the escape velocity of the planet. Since that time, several probes, from Voyager to ICE to Galileo, have used gravity assists of various kinds to push spacecraft far beyond what could have been accomplished by rocket power alone. Another technique called aerobraking can also be used to change orbits without rocket power. This was recently demonstrated with gradual plane change maneuvers by Hiten and Magellan. We have also combined aerobraking and reentry, as in the Apollo return trajectory, or the Galileo Jupiter probe trajectory. A paper in 1979 by Dunbar et. al. (which I don't have with me at the moment, exact reference available on request) demonstrated that gravity assists could be used to capture large asteroids, for a delta-V of as little as 3 km/s. More recently, new asteroids and trajectories have been discovered requiring only 2 km/s or less impulse delta-v. Trajectories that use aerobraking have not yet been published, but these could bring an additional large savings. Unfortunately, the amount of mining equipment needed to move the asteroids we know about (10^6+ tons) is too large to be economically launched at todays costs. As you point out, both long-RTLT teleoperation of this complexity and astronaut travel to the asteroid are far too expensive or complex to be viable at this time. Furthermore, the number of asteroids we know can be captured for less delta-v than the Moon is less than a dozen. However, from lunar crater studies, it is estimated that c. 100,000 objects of 100m size or greater, and c. 1,000,000 objects of size 10m or greater, exist with a delta-v to earth orbit closer than the lunar surface. If we could detect asteroids down to 10m, this would solve two problems: * Our sample size would be nearly 100,000 times larger, allowing us to select asteroids with the absolutely minimal impulse delta-v requirements: perhaps 500 m/s or less. * The mass required to move would go from 10^6 tons to 10^3 tons or less, requiring much less mining and engine equipment to get the ball rolling. Space mining technology could start small and work its way up, following the natural progression of technology from low-cost experiments to large-scale, well-known projects. Given these two advances, comet fragments could be captured with _today's_ launch costs and technology. Ice is very easy to work with compared to rock, and we can use the following of today's technologies: automated penetrators, solar-thermal engines, and mylar mirrors, have already been or will soon be demonstrated (CRAF has a large penetrator chuck full of sophisticated sampling instruments, including a scanning tunneling microscope for taking pictures of individual comet molecules). The teleoperation required is no more complex than that for CRAF itself. Asteroids are tougher, but a discovery of sufficient importance will get the ball rolling on the R&D required to produce tough, low-mass, high-thruput rock and metal mining equipment for the new vacuum and microgravity environments. This will also very likely be automated at first. Follow-on missions can have astronauts if we can bring the cost of manned spaceflight down through the use of comet mass for shielding, fuel, cooling and life-support. However, except for one c. 20m object that passed the Earth inside the orbit of the Moon this January, we have not come close to detecting such small objects. A dedicated space-based, infrared earth-crossing asteroid and comet telescope would solve this problem, detecting tens of thousands of new, smaller objects. This should be complemented be an expanded visual search, and expanded efforts to collect and study asteroid samples of all varieties from Antartica. Besides the basic problem of orbital mechanics statistics and size, there are several commercial-related problems, that if solved by exploration would greatly invigorate commercial interest: * the earth-crossing asteroid source(s) of ureleite diamonds * the possibility of easily-processed metallic regolith on the nickel-iron asteroids * the amount small water-containing fragments in the earth-crossing meteor showers, which is a function of the rate of evaporation vs. the rate of comet fragmentation Then there is the unexpected, which is the most sought after by a good explorer (see my .signature). In conclusion, the discovery of many new, smaller asteroids and comets, the solution to several outstanding problems related to commercial interests, and possible serendipitous discoveries could greatly speed up the timetable for the utilization of asteroid and comet resources. >>I'll cross my fingers that [CRAF] gets out of the planning stages. > >You and me both. Instead of crossing our fingers, let's write to our Congressmen to make _sure_ that CRAF gets out of the planning stages. Ditto for SIRTF, planned to be the most powerful infrared telescope ever launched. SIRTF is critical for find the large numbers of smaller asteroids and comets we need to get the space industry ball rolling. A dedicated asteroid/comet IRAS and a meteor-shower-following IRAS would also be good, inexpensive missions that could solve many of the outstanding pure-scientific and industry-related unknowns regarding the asteroids and comets. -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ Date: 13 May 91 15:36:21 GMT From: wuarchive!zaphod.mps.ohio-state.edu!swrinde!emory!wa4mei!ke4zv!gary@louie.udel.edu (Gary Coffman) Subject: Re: Advancing Launch Technology In article dlbres10@pc.usl.edu (Fraering Philip) writes: >In article <2798@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: > >>...down from that of a rich man's toy to everyman's car. The T wasn't >>high tech compared to the 1901 Olds, just big, dumb, reliable, cheap, >>and made in huge quanities. > >It was larger than earlier cars, but the fundamental advance >the model T made was in being mass produced. This would not have >happened if Henry Ford had tried to achieve economy of scale by >building cars large enough to hold several hundred people. Actually the T was smaller than many of it's predecessors though it could often carry more. What made it interesting was that the design was simplified for mass production. This had several interesting side effects. Such a simple vehicle was easy to maintain. Fewer parts meant less things to go wrong. Making large quanities of a standard design lowered the cost. The "any color as long as it's black" philosopy succeeded not because black was necessarily a cheaper color, but because the custom, one off, painting of special colors was avoided. This concept would work just as well for small launchers as large launchers, but I believe that the small launcher field can successfully be developed by private firms designing to meet current commercial demand. Heavy lift is going to need an initial government funded pump prime to overcome the chicken and egg effect. I'm confident that once routine relatively inexpensive heavy lift is available, payloads will be designed to use the capacity. Note that I don't even believe that an HLV has to be cheaper per pound to orbit than smaller launchers. I believe that there will be payloads that will require heavy lift because it will be cheaper to launch them assembled than to do assembly in space. Gary ------------------------------ Date: 13 May 91 23:00:11 GMT From: aio!vf.jsc.nasa.gov!kent@eos.arc.nasa.gov Subject: Re: Why the space station?y > > I was talking about the difficulties of manuvering into close proximity to the > station (or any large, open structure). While the RMS will do fine for the > final docking, that arm is only 15 meters long. Alot of effort may be > needed to get within 15 meters of the dacking adaptor without hitting the > trussd, solar pannels or heat radiators. This is a particular problem is > there is a docking failure. For example, due to a damaged radar beacon > the Progress M7 resupply craft almost rammed the Mir space station. A > ground controlled noticed in time, and aborted the docking. As the > Progress passed the station (after failing to dock) it nearly hit a solar > pannel. I feel this sort of accident is a much greater risk for Freedom, > with so many things sticking out in so many directions. > > Frank Crary > UC Berkeley Our proximity operations use a combination of onboard radar tracking and ground based tracking. Also you have active man in loop (pilot) override if the closure rate get to high. The command and pilots are not passengers during close proximity operations. I have heard and seen the active interactions between the crew, ground and the onboard and ground systems they use to approach objects in orbit. Beleive me the rates are VERY low by the time you get close. I'm talking single digit feet per second at several hundred feet out and much less at closer ranges. Sure there is some risk. space flight is just a bit risky. The risks of docking are very well managed, understood, and planned and designed for. -- Mike Kent - Lockheed Engineering and Sciences Company at NASA JSC 2400 NASA Rd One, Houston, TX 77058 (713) 483-3791 KENT@vf.jsc.nasa.gov ------------------------------ Date: 13 May 91 07:47:27 GMT From: agate!hailstorm.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Re: Launch Costs In article <1991May11.223846.422@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes: >Also, consider that it the cost/lb of the Pegasus can probably be >reduced considerably. Two more or less straightfoward improvements >are: higher Isp liquid fuel upper stage(s) and the addition of ramjets >to the first stage (as was done with the X-15 at one point, admittedly >with near-disasterous results). Nobody has yet done a cost/benefit tradeoff that I've seen released on putting a Higher Isp upper stage on Peg. My instinct is that it might not be cost effective... it might add $5 million easily to the price. Ramjets, however, have less moving parts and are somewhat easier to do than rocket engines... and very conveniently, the Pegasus first stage quits at Mach 8 and 120?thousand feet, about the limits of Ramjets. 8-) -george ------------------------------ Date: 13 May 91 16:13:36 GMT From: snorkelwacker.mit.edu!thunder.mcrcim.mcgill.edu!quiche!msdos@apple.com (Mark SOKOLOWSKI) Subject: Honking at cyclists... Given all the flames that my article has, I want to simply add this: My point is that we'll have to expand our energy consumption and our vital space NO MATTER WHAT goes on. Of course we can improve our efficiency to use this or that source of energy and matter, but sonner or later we'll have to use the minerals of Antarctica, the deuterium in the Earth's oceans, and go to the moon in order to build a plateform there for Mars, Marcury and the asteroids. Our ever increasing population will need more and more, and each individual will need more and more of everything. And sooner or later even the entire solar system won't be sufficient, so we'll have the rest of the galaxy... Mark ------------------------------ Date: 13 May 91 17:35:28 GMT From: dftsrv!dpalace@mimsy.umd.edu (Dick Palace) Subject: Pegasus/SMEX/-Alive and Will -- Dick Palace Goddard Space Flight Center (301) 286-9464 dpalace@sunland.gsfc.nasa.gov ------------------------------ Date: 13 May 91 21:29:06 GMT From: mintaka!ogicse!sequent!muncher.sequent.com!szabo@bloom-beacon.mit.edu Subject: Re: Launch Costs XXIV -- Wright Bros. Flyer to carry tanks to Kuwait! In article <2814@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: > >I'm of the opinion that small cheaper launchers will emerge without >NASA's help. What if NASA hires away the engineers, or takes away the payloads with launches subsidized at taxpayer expense? Why should NASA be going against industry and its trends, rather than helping and enhancing what industry finds the most useful? >I think that government funding will be necessary to prime the pump >for a cheap heavy lift vehicle. I know also that presently there is >no market for such a HLV. Again, I believe that when such capability >becomes routinely available, a market will develop. "To boldly go where many men have gone before." :-) -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ Date: 13 May 91 21:32:49 GMT From: usenet@ames.arc.nasa.gov (Peter E. Yee) Subject: Systems Analysis Office created in line with Augustine Report (Forwarded) Jeff Vincent Headquarters, Washington, D.C. May 13, 1991 (Phone: 202/453-8369) RELEASE: 91-74 SYSTEMS ANALYSIS OFFICE CREATED IN LINE WITH AUGUSTINE REPORT NASA Administrator Richard H. Truly today announced the establishment of a new Systems Analysis and Concepts Office at NASA Headquarters and designated James D. Bain as its Director. The creation of the office is another step in NASA's implementation of recommendations made last December by the Advisory Committee on the Future of the U.S. Space Program, also known as the "Augustine Committee." The committee recommended that a Systems Analysis and Concepts Office be established to provide independent and non-advocate decision support to the NASA Administrator and his immediate office. The group would focus on policy alternatives, conceptual and formulative stages of new programs, and systematic review of the requirements and benefits of new and ongoing programs. The committee further recommended that the new office be staffed by a very few experienced analysts and that it be augmented by a Federally Funded Research and Development Center (FFRDC). Truly has reviewed several existing FFRDCs from the perspective of their ability to augment the new office. Following that review, he decided to let FFRDC support gradually evolve by tasking analysis of specific issues to one or more appropriate FFRDCs. In a separate recommendation, the Augustine Committee proposed the establishment of an independent cost analysis function to serve the Administrator and his immediate office. In response to that recommendation, Truly has decided to significantly augment the independent cost capability recently initiated by the NASA Comptroller. This group will report administratively to the Comptroller and provide independent assessments to the Administrator and his immediate office, to include the new Systems Analysis and Concepts Office. Bain previously served as the Executive Secretary to the Augustine Committee and is currently staffing the implementation of the committee's recommendations within NASA. ------------------------------ End of SPACE Digest V13 #547 *******************