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 ; Tue, 1 Jan 1991 04:24:02 -0500 (EST) Message-ID: <8bU5HLi00VcJM14k5j@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 1 Jan 1991 04:22:37 -0500 (EST) Subject: SPACE Digest V12 #708 SPACE Digest Volume 12 : Issue 708 Today's Topics: Re: Photon engine Payload Status for 12/17/90 (Forwarded) Ulysses article Ulysses Update - 12/17/90 Bussard ramjet question NASA Headline News for 12/17/90 (Forwarded) Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: Mon, 17 Dec 90 23:35:16 EST From: John Roberts Organization: National Institute of Standards and Technology formerly National Bureau of Standards Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. To: space@andrew.cmu.edu Subject: Re: Photon engine >From: sdd.hp.com!samsung!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) >Subject: Re: Photon engine >In article <9012040003.AA21365@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >>React the matter and antimatter inside a huge chunk of radiation-absorbing >>refractory material, and I bet most of the intermediate particles would break >>down inside. Of course the neutrinos would still get out, and there doesn't >>seem to be any way of directing them for propulsion. Any idea of (a) the >>percentage of energy wasted in this way, or (b) the impulse per Joule- >>equivalent of neutrinos as compared with photons? ... >The neutrinos would contribute essentially nothing to thrust, even if you >could beam them somehow. Given the whichness of the why and all, I strongly suspect that the momentum of a neutrino is equal to (energy-equivalent / c), same as for photons and matter moving very close to c. What I don't know is the energy-equivalent of a neutrino (is there more than one level?), and the percentage of energy "wasted" by neutrino radiation in a typical matter-antimatter reaction. If for some reason the percentage is high, and the neutrinos are mostly produced by the breakdown of intermediate particles as you described, that could possibly tilt the balance in favor of reaction mass versus pure photon drive. >However, I think you miss the point, John. You don't *want* to absorb the >particles, if your objective is a near-photon engine. Beaming the particles >is vastly easier than beaming high-energy gamma rays, and you don't lose >anything by working with the particles -- they carry no less momentum than >the photons they will decay into. Well, maybe a *very* tiny bit less. >The only time you want to absorb the particles is if you are using them to >heat much larger amounts of reaction mass, for higher thrusts and lower >antimatter consumption at the price of much lower exhaust velocity. In >that case, there is some possibility that reacting the antimatter with >heavier nuclei might be a win, as more of the energy might be caught >in charged fragments. I was trying to describe a completely theoretical pure-photon drive powered by a matter-antimatter reaction, not an actual working antimatter drive that someone might seriously propose. The system I described would use the power source to heat the mass, then drive from the *thermal* radiation of the mass, somehow made as directional as possible. No matter would be exhausted. Of course, nobody in their right mind would actually build such a system, but as we know, "net.space means never having to say you're serious". In the original discussion, I was pointing out that in every practical case, from an energy-efficiency standpoint (engineering details more or less ignored), a photon (much less laser) drive from an internal power source makes much less sense than other approaches. As a concession to the photon enthusiasts, I found *one* exception: if you have available large quantities of a fuel which can be "burned" to produce "pure energy" (represented by a 50-50 mix of matter and antimatter in this case), and if this "fuel" is cheap enough that cost is not a consideration (certainly not the case with antimatter), and if the engineering problems are all solved in an elegant manner (highly unlikely), then you get a very slight marginal advantage in filling up your tanks with "fuel" and exhausting the output as a directed beam of pure photons, as compared to reserving some of your (fixed) tank space for inert reaction mass. Since nobody's going to do that, I think that pretty much kills the internally-powered photon drive concept completely. >"The average pointer, statistically, |Henry Spencer at U of Toronto Zoology >points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 17 Dec 90 19:38:30 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Organization: NASA Ames Research Center, Moffett Field, CA Subject: Payload Status for 12/17/90 (Forwarded) Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu Daily Status/KSC Payload Management and Operations 12-17-90 - STS-35 ASTRO-1/BBXRT (at DFRF) Support for DFRF operations continue. - STS-39 AFP-675/IBSS/STP-01 At the VPF, SPAS will be rotated to vertical and it's keel will be installed. Also, SPAS CYRO servicing wil be performed today. At the OPF, CRO battery charging will be active today. - STS-40 SLS-1 (at O&C) Power up testing will continue today. - STS-37 GRO (at PHSF) No work is scheduled for today. - STS-42 IML-1 (at O&C) Preps for rack and floor installation and paper closure continues. - STS-45 Atlas-1 (at O&C) Experiment and pallet staging continue. - STS-46 TSS-1 (at O&C) Partial pallet destaging continues. Also the MPESS will be moved to the north rails today. - STS-47 Spacelab-J (at O&C) No work is scheduled for today. - STS-67 LITE (at O&C) Hard point installations continue. ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 17 Dec 90 23:15:30 GMT From: swrinde!elroy.jpl.nasa.gov!mahendo!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Organization: Jet Propulsion Laboratory, Pasadena, CA. Subject: Ulysses article Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu Associate Press -- 12/14/90 By Lee Siegal "The Ulysses spacecraft is wobbling like an off-balance washing machine, threatening to cripple the $750 million U.S. - European mission to study the sun's poles." Officials hope they can work around the malfunction so it doesn't disrupt the five-year mission by preventing the dish-shaped main antenna from pointing at the Earth according to Siegal. Said the European Space Agency's Edgar Page, "If we can't do anything about it, it's very serious." The loss of data could range from 20 percent to 90 percent. JPL Ulysses project manager Willis Meeks is quoted in the wire service story, "Gloom is something I don't feel -- I'm sure that somehow during the next four years we'll find a way to learn to live with this problem." Repeated firing of the craft's thrusters was one possibility offered. Ulysses problem is yet another in a series for NASA. (Hubble, fuel leaks, Astro-1, recounted) The slow wobble began Nov. 4, upon extension of a 24 1/2 foot-long antenna boom. The wobble is expected to diminish then increase as the probe nears the sun polar latitudes, says AP. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 18 Dec 90 00:49:17 GMT From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Organization: Jet Propulsion Laboratory, Pasadena, CA. Subject: Ulysses Update - 12/17/90 Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu ULYSSES STATUS REPORT December 17, 1990 On December 11, the 3rd meeting of the Nutation Investigation Team took place to review the current situation and to discuss future strategy. The major output of this meeting was to commence Conscan operations and to observe its effect on the nutation-like behavior. The Conscan system on board the spacecraft is designed to keep the High Gain Antenna pointed at the Earth. It is an optional system which can be switched in and out of use as desired operationally. The successful use of Conscan for reducing nutation-like motion was therefore a very important element in planning future operational strategies. Following the meeting, a slew manuever was carried out which placed the antenna pointing such that on December 12 center-of-Earth pointing would be achieved. On December 12 Conscan was switched on for 20 minutes and reduced the nutation-like motion to within the deadband which had been set on board prior to the operation (0.23 degrees). Since Conscan had been so successful in reducing the nutation, it was decided to further reduce the deadband by one half and to leave Conscan for an extended period. This operation was done and the nutation-like motion was reduced to within the deadband set (0.125 degrees). After 2 hours Conscan was switched off. The nutation then built up until after 8 hours, it had reached a value of 1 Degree half-cone. On December 14 Conscan was switched on again but with an Earth-pointing offset of 0.8 degrees which had occurred by natural drift since the last manuever. Once again the system was able to correct for the offset and reduce the nutation to within the deadband. After Conscan was switched off the nutation increased over a period of 12 hours to a new stable value of 0.75 degrees half-cone. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 18 Dec 90 01:24:25 GMT From: celit!dave@ucsd.edu (Dave Smith) Organization: FPS Computing Inc., San Diego CA Subject: Bussard ramjet question References: <1990Dec17.235935.10244@news.arc.nasa.gov> Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu OK, I was thinking about Bussard ramjets the other day (after reading entirely too much science fiction) and got to wondering: How do you decelerate with a Bussard ramjet? Your fuel (and reaction mass) is coming at you, you would have to catch it and then accelerate it back the other way. Do you have a fuel tank you fill up on the way for deceleration? Is there enough friction against the ramscoop fields to slow you down in a reasonable amount of time? Has my brain been turned into mush? -- David L. Smith FPS Computing, San Diego ucsd!celit!dave or dave@fps.com "You can"t build a national and international network using TCP/IP" --Laurie Bride, Boeing Computer Services ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 17 Dec 90 19:37:51 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Organization: NASA Ames Research Center, Moffett Field, CA Subject: NASA Headline News for 12/17/90 (Forwarded) Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu Headline News Internal Communications Branch (P-2) NASA Headquarters Monday, December 17, 1990 Audio Service: 202 / 755-1788 This is NASA Headline News for Monday, December 17, 1990 Administrator Richard H. Truly will offer a live holiday address to NASA employees tomorrow at 12:00 noon Eastern time on NASA Select television. In addition to his personal message to employees, he is expected to comment on the Augustine panel report and the subsequent senior management meeting. * * * * * * * * * * * * * * * * * * * * * * * * * * Weather fronts across the U.S. delayed the departure of the Space Shuttle Columbia and its 747 carrier aircraft for Florida, yesterday. Originally scheduled to depart from NASA's Dryden Flight Research Facility, Edwards, Calif., Sunday, the mated-combo is now expected to begin its cross- country ferry flight at 4:00 pm Eastern time today. First stop on the initial leg of the flight will be Biggs AFB, El Paso, Texas, where the two craft will remain overnight. Tuesday, the Columbia ferry will continue to Barksdale AFB, Lousiana and then proceed on to Kennedy Space Center, Florida. At Kennedy Space Center, an emergency powerdown was performed on the Space Shuttle Discovery Friday night when a relay transformer in the uninterruptable power source in the Launch Control Center failed. The transformer was replaced and power was restored about 16 hours following the shutdown. No damage resulted from the outage. Work is continuing on Discovery, preparing it for powerdown Friday in preparation for the holidays. The right hand OMS pod will be installed tonight, and the Forward Reaction Control system is scheduled to be installed Thursday. Atlantis is currently unpowered and was unaffected by the outage. * * * * * * * * * * * * * * * * * * * * * * * * * * Controllers at the Jet Propulsion Laboratory are watching over Ulysses as its "wobble" continues to decrease. Media reports over the weekend included a "worst case scenario" that indicated a major loss of data, as the spacecraft passed over the sun's poles. Project Manager Willis Meeks is confident that a thruster routine can be worked to dampen out the wobble, and insure communications with the craft as it performs its solar-polar science gathering. Here's the broadcast schedule for Public Affairs events on NASA Select TV. All times are Eastern. **indicates a live program. Monday 12/17/90 1:00 pm NASA Radio Programs (audio) Tuesday 12/18/90 12:00 noon Holiday Message from NASA Administrator Richard H. Truly Wednesday 12/19/90 1:00 pm Galileo Press Conference from JPL Thursday 12/12/90 2:00 pm STS-35 Crew Post Flight Press Conference from JSC All events and times may change without notice. This report is filed daily, Monday through Friday, at 12:00 pm, EST. It is a service of Internal Communications Branch at NASA Headquarters. Contact: CREDMOND on NASAmail or at 202/453-8425. NASA Select TV: Satcom F2R, Transponder 13, C-Band, 72 degrees West Longitude, Audio 6.8, Frequency 3960 MHz. ------------------------------ End of SPACE Digest V12 #708 *******************