Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from holmes.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Wed, 22 Mar 89 05:17:36 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 22 Mar 89 05:17:28 -0500 (EST) Subject: SPACE Digest V9 #305 SPACE Digest Volume 9 : Issue 305 Today's Topics: Teleoperation GM Sunrayce 1990--the Stanford entry. Moronic TV news coverage Re: Black hole trolling Re: Sanger Re: space news from Dec 19/26 AW&ST Re: space news from Dec 19/26 AW&ST Samara Probe for Remote Imaging Re: Samara Probe for Remote Imaging Re: Samara Probe for Remote Imaging ---------------------------------------------------------------------- Date: 18 Mar 89 21:59:38 GMT From: fas.ri.cmu.edu!schmitz@pt.cs.cmu.edu (Donald Schmitz) Subject: Teleoperation In article (Eric Harnden) writes: ... >reply to... but i think that, while his data is of course correct, there is >a point missing. the delay time is real, and has one of two possible results. >the delay will either require that the operator think D time ahead (where D >is the *cumulative* roundtrip delay), which may be possible for simply >driving a motorized device across a land/station-scape, or, when the >imprecision inherent in such a mode is unacceptable, will have to wait D >time between initiation of each step in a movement task. this waiting will >be of such an order as to allow the operator to relax his concentration >between each command, without actually having time to think about anything >else. this sort of stop-go in his head will have the same effect that it >does driving in city traffic: fatigue will set in quickly. how might we >reduce its' effects? I have heard anecdotal evidence that rapid fatigue does occur for long delay (> 0.5 sec) teleoperation - also that the delay causes a very cautious operation, such as breaking a move up into a number of very short, slow moves. One solution is to provide the operator with a non-delayed simulation of the robot/workspace, supposedly this brings the efficiency up to what is expected by imposing the delay (Dr. Minsky's calculation). Still, it seems likely that with lots of practice (years), operators may be able to adapt to the delay, much as humans adapt to other un-natural situations, such the famous inverting eye-glasses experiment, or developing the eye-hand coordination needed for video games, driving, etc. (although after adapting, they may not be able to handle real-time responses again - I'm not sure I'd want to try this). Don Schmitz -- ------------------------------ Date: 18 Mar 89 22:15:32 GMT From: Portia!hhughes@labrea.stanford.edu (Mohamad Ali) Subject: GM Sunrayce 1990--the Stanford entry. General Motors is sponsering a SOLAR POWERED CAR RACE in the summer of 1990. A few students at Stanford have decided to build a vehicle to enter in the race. Still in its infancy, the project has already attracted a dazzling array of highly talented individuals. Our designs represent technology at its frontier. However, despite the fact the Stanford is known to the world as a rich institution, we cannot expect from the university but a small fraction of what it will cost to put the vehicle together. We are more than willing to accept contributions in the form of money, parts (production line or experimental) or just simply advice. If anyone out there knows of an organization that might support our effort, please send me a name and address at: hhughes@portia.stanford.edu (415) 329-1047 Thank you, Mohamad. Manager of Finances, Stanford Solar Car Project 1990. ------------------------------ Date: Fri, 17 Mar 89 10:30:50 PST From: Peter Scott Subject: Moronic TV news coverage mfci!rodman@yale-bulldog.arpa (Paul Rodman) writes: >After watching another shuttle launch and flipping desperately between >channel 4 and CNN, I very much wish for a channel that would tell >the commentator to SHUT-UP during the launch. >Can't I PLEASE hear and see the NASA feeds? Do we have to have the >lowest common denominator? Isn't NASA Select available on some cable feeds? Perhaps you should be talking to your local cable franchise. When there's a launch I go to JPL's mission control center, they slave the video screens to the feeds from the Cape and JSC. I had the same reaction to the network commentators as you a long time ago. pjs@grouch.jpl.nasa.gov ------------------------------ Date: Fri, 17 Mar 89 12:43 EST From: Subject: Re: Black hole trolling Scott Henry writes: >> kpmancus@phoenix.Princeton.EDU in s.cs.uiuc.edu:sci.space : >> Easy. The forces that hold a macroscopic object together are >> electromagnetic. They require the exchange of virtual photons between >> the particles to be held together. When the object extends across the >> event horizon, the photons can no longer go from the atoms inside the >> black hole to the atoms outside. Thus the tether is neatly sliced. > >This is incorrect. The definition of the event horizon is the point at >which photons cannot escape to *infinity*. This in no way implies that >they cannot cross the event horizon, they just cannot make it very far >past it (depending on how deep they started). The bonds between atoms >(nucleons) would begin to behave *oddly* as the energy of the virtual >photons (gluons) would be different as seen by the higher and the lower >(gravitationally speaking) particles. How oddly? Who's interested in a PHd >thesis (maybe only a Masters)? This is inherently incorrect. Double-null coordinates on the event horizon have a light-cone parallel to the event horizon surface, which means that no particle can cross the event horizon itself. He would do better to read how Hawkings, Wheeler, Israel, and others talk about the event horizon, rather than stating a partial definition and then making an illogical extrapolation. The first appender is correct - the tether will be sliced. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Arnold Gill | If you don't complain to those who | Queen's University at Kingston | implemented the problem, you have | gill @ qucdnast.bitnet | no right to complain at all ! | -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ Date: 16 Mar 89 09:14:36 GMT From: mcvax!kth!draken!tut!router!opmvax!siili@uunet.uu.net (Tero Siili) Subject: Re: Sanger In article <7234@thorin.cs.unc.edu>, symon@lhotse.cs.unc.edu (James Symon) writes: > In article <1989Mar14.172237.29235@cs.rochester.edu, > dietz@cs.rochester.edu (Paul Dietz) writes: >> . . . Sanger would use turboramjet engines to propel a winged >> first stage to Mach 5, at which point a LOX/LH2 propelled second stage >> -- either an unmanned expendable cargo rocket (like Pegasus) or a >> reusable winged manned vehicle -- would be released to ascend to >> orbit. > > Is the battle against high density air also a small percentage of the > effort and not worth it? How much of the work of an expendable first > stage could be done with an aircraft without significant design > innovation? Would effort be more profitably expended in going for > altitude or speed? What's the d/d$? I believe, that the ideas behind the Sanger concept are twofold: the purpose is to develop a first stage for orbital launches and use the same development for a Mach 5 hypersonic passenger plane. As an hypersonic transport, the Sanger would carry 130 passengers a distance of approx. 13 000 km(8100 miles for those, who still use archaic units...). The second idea is to have a space transportation system, which would be able to lift-off from Europe but still be able to launch to any inclination orbit. This would be achieved by cruising after take-off e.g. to equator and separating the second stage only after that. Third factor is, that by combining the first stage/hypersonic transport concepts and using the Hermes experience in the Horus(the manned second stage) development, the development costs could be reduced. Planned launch costs with Horus would be 10-15 % of Hermes launch cost and with Cargus(unmanned second stage) one third of the Ariane V cost. Additional advantage - according to two-year old info - would be, that Sanger presumably could take off from an ordinary airport, unlike HOTOL. The reason for this is(if my recollection is correct), that Sanger first stage uses turbojets at low speeds and changes to ramjet operation after Mach 1 AND the engines use kerosene as fuel. HOTOL takes off using rocket operation AND uses liquid hydrogen as propellant; rocket take-off is apparently noisy and perhaps the use of LH2 at take-off creates additional risks. The Sanger second stage, Horus, is using LO2/LH2 combination. As a conclusion, the advantages of the Sanger concept are in its flexibility and reusability and the in fact, that the technologies assumedly are not as complex as the ones developed for the NASP(e.g. turboramjet vs. scramjet and no SSTO capability). References: Article 'Future Spaceplanes' in 'Spaceflight', June 1987. Nos. 6/7, vol. 29. A brief story of a presentation by Dr. H. Kuczena of the company MBB. 'The German SANGER Space Transport System'. Presentation material/brochure by MBB/May 1986. regards, Tero Siili Finnish Meteorological Institute, Dep. of Geophysics siili@csc.fi P.S. For further info on Sanger, contact MBB directly; if necessary, I can post their PR division address ------------------------------ Date: 16 Mar 89 17:52:00 GMT From: m.cs.uiuc.edu!s.cs.uiuc.edu!carroll@uxc.cso.uiuc.edu Subject: Re: space news from Dec 19/26 AW&ST /* Written 9:45 pm Mar 12, 1989 by henry@utzoo.uucp in s.cs.uiuc.edu:sci.space */ /* ---------- "space news from Dec 19/26 AW&ST" ---------- */ (...) The US launch industry is in good shape right now, but will have lean years to weather when the current payload backlog is exhausted. The habit of depending on the government won't help; Martin Marietta's president observes that there is *no* commercial launch industry in existence right now, only various degrees of government support. Long March will be a nasty competitor; if there is a quota on Long March launches, there will be a problem deciding who gets them (they will probably remain cheaper than Western launches). /* - - - - */ Sally Ride was here at the U of I recently, and she had a chart with ``Expected payload needs'' and ``Expected payload capacity'' in lbs/year, and the first was significantly larger than the latter, not even counting any SDI launches. I believe she was only counting government (NASA & DoD) capacity, so it may be that this excess would not legally be able to spill into the private sector. Alan M. Carroll "And then you say, carroll@s.cs.uiuc.edu We have the Moon, so now the Stars..." - YES CS Grad / U of Ill @ Urbana ...{ucbvax,pur-ee,convex}!s.cs.uiuc.edu!carroll ------------------------------ Date: 19 Mar 89 03:06:26 GMT From: attcan!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: space news from Dec 19/26 AW&ST In article <218100015@s.cs.uiuc.edu> carroll@s.cs.uiuc.edu writes: >The US launch industry is in good shape right now, but will have lean >years to weather when the current payload backlog is exhausted... > >Sally Ride was here at the U of I recently, and she had a chart with >``Expected payload needs'' and ``Expected payload capacity'' in lbs/year, >and the first was significantly larger than the latter, not even >counting any SDI launches... In any such comparison, one has to delete shuttle-unique payloads and those that are committed to the shuttle by administrative decision. The *shuttle* has a serious capacity shortage that will not soon clear up. Pseudo-commercial expendables, however, won't be in quite such short supply once the Challenger backlog clears. -- Welcome to Mars! Your | Henry Spencer at U of Toronto Zoology passport and visa, comrade? | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 16 Mar 89 04:06:00 GMT From: pur-phy!tippy!fireman@ee.ecn.purdue.edu Subject: Samara Probe for Remote Imaging Reprinted from "NASA Tech Briefs," February, 1989. "This conceptual device would scan automatically, without costly aiming or stablizing devices." - NASA's Jet Propulsion Laboratory, Pasadena, California A proposed imaging probe would descend through the atmosphere of a planet, obtaining images of the ground surface as it travels. The probe could be released from an aircraft over the Earth or from a spacecraft over another planet. The probe would have a body and a single wing shaped like much like a samara - a winged seed like those of maple trees. It would therefore rotate as it descends, providing a panoramic view of the terrain below. The probe would radio the image obtained by its video camera to the aircraft or spacecraft overhead. The probe would be simple and inexpensive. It would contain no moving parts and would need no fuel or power for scanning, because its panning motion would be imparted by aerodynamic forces. Several such probes could provide comprehensive, detailed maps of a region without the complexity of horizontal travel on the surface or through the atmosphere. The wing would be propeller shaped and would be pitched for the desired rate of descent and rotation. The camera (or radar) would be mounted on the lower part of the probe at a fixed angle with the repect to the spin axis. The field of view of the camera lens would determine the required amount of overlap of the image on successive rotations; a wider angle would cause more - and earlier - overlap. The resolution of the image would increase gradually as the probe approaches the surface. The upper surface of the wing could carry solar-cell panels, if necessary, to supply power to the camera and transmitter. The transmitting antenna would be embedded in the probe. The wing could also a Sun sensor to furnish data on orientation and spin to aid in subsequent processing of the images. (Image processing would be required to remove effects due to nutation and wind drift.) A second wing, like that on certain seeds, could be added to slow the descent and reduce nutation. [This work was done by James D. Burke of Caltech for NASA's Jet Propulsion Laboratory.] ------------------------------ Date: 17 Mar 89 18:22:09 GMT From: att!cbnewsl!sw@ucbvax.Berkeley.EDU (Stuart Warmink) Subject: Re: Samara Probe for Remote Imaging In article <10900004@tippy> fireman@tippy.uucp writes: >Reprinted from "NASA Tech Briefs," February, 1989. > >[...] The probe would have a body and a single wing shaped like much like a >samara - a winged seed like those of maple trees. It would therefore rotate >as it descends, providing a panoramic view of the terrain below. The probe >would radio the image obtained by its video camera to the aircraft or >spacecraft overhead. [...] This sounds like an excellent idea - a very (conceptually) simple method of scanning large areas and obtaining high-res pictures nearer the surface. The probe might even survive the landing, but the camera might not see much... The weight of the wing and fixed camera would have to be less than the weight of a scanning camera and parachute for the method to be more efficient on a weight basis, though, but it would be inherently more reliable. A fast "shutter speed" (or perhaps some simple rotational motion compensation) would be required to prevent blurring of the pictures. There is some trade-off here, as a larger wing would decrease the spin rate, but would increase the weight of the probe. The blurring of the pictures could be a real problem for such "way-out" bodies as Titan and Triton, where the Sun's light is obviously much dimmer than for Venus, the Earth and Mars. For the same reason, batteries would have to be substituted for the solar cells (and might be required anyway.) How the probe would actually enter an atmosphere (from orbital velocity) is another interesting subject - could the outside of the probe be made out of carbon-carbon compounds, like parts of the Shuttle? Hmmm.... I'd be interested in finding out more about this whole idea! -- ------------------------------------------------------------------------------ "PENTAGON OFFICIALS ARE CONCERNED ABOUT | Stuart Warmink, Whippany, NJ, USA AN ANTIMATTER SHORTAGE" ("WHAT'S NEW") | sw@cbnewsl.ATT.COM (att!cbnewsl!sw) -----------> My opinions are not necessarily those of my employer <----------- ------------------------------ Date: 18 Mar 89 05:45:37 GMT From: phoenix!mbkennel@princeton.edu (Matthew B. Kennel) Subject: Re: Samara Probe for Remote Imaging In article <287@cbnewsl.ATT.COM> sw@cbnewsl.ATT.COM (Stuart Warmink) writes: }In article <10900004@tippy} fireman@tippy.uucp writes: }}Reprinted from "NASA Tech Briefs," February, 1989. }} }}[...] The probe would have a body and a single wing shaped like much like a }}samara - a winged seed like those of maple trees. It would therefore rotate }}as it descends, providing a panoramic view of the terrain below. The probe }}would radio the image obtained by its video camera to the aircraft or }}spacecraft overhead. [...] } }This sounds like an excellent idea - a very (conceptually) simple method }of scanning large areas and obtaining high-res pictures nearer the surface. }The probe might even survive the landing, but the camera might not see much... } } } }A fast "shutter speed" (or perhaps some simple rotational motion compensation) }would be required to prevent blurring of the pictures. There is some trade-off }here, as a larger wing would decrease the spin rate, but would increase the weight }of the probe. The blurring of the pictures could be a real problem for such "way-out" }bodies as Titan and Triton, where the Sun's light is obviously much dimmer than }for Venus, the Earth and Mars. Presumably, one could use CCD's, which have close to single-photon sensitivity. (So do dark-adapted human eyes, believe it or not!) If the ambient enviroment is sufficiently cold, cryogenic equipment might not be necessary. Matt Kennel mbkennel@phoenix.princeton.edu ------------------------------ End of SPACE Digest V9 #305 *******************