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 ; Sat, 24 Mar 90 01:57:50 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 24 Mar 90 01:57:22 -0500 (EST) Subject: SPACE Digest V11 #183 SPACE Digest Volume 11 : Issue 183 Today's Topics: Re: Strange flash of light guidance and navigation systems, request for literature Venus balloons Orbital Sciences Public Offering Comet Austin ---------------------------------------------------------------------- Date: 22 Mar 90 16:06:29 GMT From: ddsw1!corpane!sparks@gargoyle.uchicago.edu (John Sparks) Subject: Re: Strange flash of light The other day there was a display of the Aurora B. seen from here (Louisville, KY) around 9PM. The weatherman talked about it and the great number of calls he received by onlookers wondering what the strange red light was in the sky. According to him, we are in a period of heavy solar magnetic activity and this allows the A.B. to be seen much further south than normal. He said to expect to see it more often in the next few days. This strange flash of light could have been the same type of phenomena. -- John Sparks | D.I.S.K. 24hrs 1200bps. Accessable via Starlink (Louisville KY) sparks@corpane.UUCP <><><><><><><><><><><> D.I.S.K. ph:502/968-5401 thru -5406 We are the people our parents warned us about. ------------------------------ Date: 23 Mar 90 18:37:28 GMT From: mcsun!ukc!harrier.ukc.ac.uk!has@uunet.uu.net (H.A.Shaw) Subject: guidance and navigation systems, request for literature With all the talk about HST and its various guidance systems someone might be able to point me in the right direction, at least at some books on the subject. I have the following problem... Some freinds of mine go out 4-wheel-drive racing. The cars are driven long distances over extremely rough ground, and it is important for the drivers to know in advance about the course. Before the race they are given a list of items of the form: 100 m 35 degree left 235 m 90 degree right The cars are fitted with a microcomputer of my own design based on a Motrola 6809 CPU. The computer monitors engine temperatures, fuel use, engine run time, slippage on the 4 wheels and differential wear, and several other things. It may be programmed with the map list and provides estimated times/distances to each item based upon wheel rotation. The problem is that the cars work in mud and spend a considerable length of time in the air! The rotations of the wheels do not correspond to distance, and so I need a positioning system. I have an ultrasonic system in my road car that uses doppler shift to get road speed and it works well. In the rally car it appears impossible to find any part of the car with a view of the road that doesn't get caked in mud (one of the drivers got sand INSIDE the crankcase of one car!). The solution seems to be an inertial system. I need a one dimensional distance measurement that is enclosed and provides resolution of 1 meter at speeds of up to 150 MPH. It must have VERY GOOD vibration handling and reject motion in the non-forward direction. The problem is solvable, but my budget runs to hundreds of pounds only. The computer could handle position, distance, velocity, or acceleration as inputs. I think acceleration might be the best bet. Can anyone help! This problem must have been solved before, I really need a pointer to the right books. Thanks for reading this, although it's not directly about space many of the people who read this group know about guidance. I have considered light aircraft radio navigation using beacons, or commercial radio transmissions, but rejected it because of poor resolution. Email: has@ukc.ac.uk | Howard Allan Shaw. Phone: +44 227 764000 Extn: 3834 | Room 111A, Physics Laboratory, | The University, | Canterbury, England. CT2 7NR ------------------------------ Date: Fri, 23 Mar 90 20:08:51 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Venus balloons >From: csusac!csuchico.edu!petunia!usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@ucdavis.ucdavis.edu (Brian or James) >Subject: Re: The Amazing Flying Coilgun > More seriously, balloons will probably be useful for research >on planets like Venus or Titan which have dense atmospheres (I wonder >what the lift strategy is for the cyntherian balloon, since a hot-air >balloon would have to be hotter than the 600 degree atmosphere) and >the gas giants, which have nothing *but* dense atmospheres. > JDN As I mentioned a few weeks ago, the atmosphere of Venus is ideal for balloons (assuming an appropriate material can be found), because it is composed mostly of carbon dioxide, and is thus very dense. Many different gases should be buoyant in a CO2 environment (extrapolating from relative density at near- normal pressure). Among the reasonable choices might be nitrogen, methane, water vapor, and neon. Oxygen would be desirable since it's available locally, but it's a little on the heavy side, and it might be too reactive. If you can get a balloon high enough, you might be able to use the temperature differential to power a heat engine. With sufficient heat flow, you could even have a "hot CO2" balloon, and you wouldn't have to worry about leakage. A chart I saw implies that the temperature drops off ~9 degrees C for every kilometer of altitude. The local CRC Handbook refuses to tell me the densities of these gases at Venus surface conditions. Does anybody know? Are they still in the same ratio as at STP? John Roberts "They also serve who only stand and wait." roberts@cmr.ncsl.nist.gov "They also wait who only stand and watch." ------------------------------ Date: 23 Mar 90 17:06:05 GMT From: rochester!dietz@pt.cs.cmu.edu (Paul Dietz) Subject: Orbital Sciences Public Offering There's an article about OSC in today's Wall Street Journal (page 1, left column). OSC will be completing a public offering in the near future. My stockbroker says the price is $13/share, but the stock is not yet trading. I've asked him to get me a prospectus. I probably won't buy until after a successful test, though. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Fri, 23 Mar 90 19:57:03 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Comet Austin Have there been any reports on where Comet Austin will be most easily visible? I remember when Halley's comet came - it was reportedly very impressive in the southern hemisphere, but hard to see in the northern hemisphere. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ End of SPACE Digest V11 #183 *******************