Date: Sun, 13 Dec 92 05:04:04 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #540 To: Space Digest Readers Precedence: bulk Space Digest Sun, 13 Dec 92 Volume 15 : Issue 540 Today's Topics: AmRoC Cassini Undergoes Intensive Design Review DC info DC vs Shuttle capabilities DoD launcher use Jet Lag Magellan Update - 12/11/92 NASA Select mission coverage One Small Step for a Space Activist... (vol 3 no 12) Space Tourism SSF Deputy Dir. Interview Terminal Velocity of DCX? (was Re: Shuttle ...) (3 msgs) what the little bird told Henry (2 msgs) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 12 Dec 92 19:56:25 GMT From: George C Harting Subject: AmRoC Newsgroups: sci.space Hello out there... I was wondering if anybody had any recent info about Amroc's Hybrid rocket? Perhaps even hybrid rockets in general... Personally, I like the company's philsophy of building a rocket with a true commercial market in mind - i.e. no pork barrel government money for development and started independently. However, it seems that they have always been running into problems trying to get their design to work (I think only one successful test of the 75Klbf engines ever worked). And they have never had an actual launch! Anyway,have hybrid rockets ever been used? I heard that they may have been for small missiles but nothing as large scale as Amroc's. George I have no friggin' .sig! ------------------------------ Date: 11 Dec 92 16:56:09 GMT From: Steve Flanagan Subject: Cassini Undergoes Intensive Design Review Newsgroups: sci.space hayim@locus.com (Hayim Hendeles) writes: >In article <1992Dec10.053616.8145@news.arc.nasa.gov> baalke@kelvin.jpl.nasa.gov writes: >> ... >> After flybys of Venus (twice), Earth and Jupiter as it loops >>around the sun to pick up energy, Cassini will arrive at Saturn >>in November 2004, beginning a four-year orbital tour of the >>ringed planet and its 18 moons. The Huygens probe will descend to >>the surface of Titan in June 2005. >Pardon my asking an ignorant question, but I can't understand why it >should take 7 years to get to Saturn. When Voyager went to Jupiter and >Saturn, it took (if I recall correctly) 4 years and a Jupiter flyby to >make it to Saturn. Here, you are using 4 flybys, and it's taking you 7 >years! I would think that if you were to adjust the launch date so that >Jupiter and Saturn were in the same relative positions as they were in >1977 (when Voyager was launched), you could do the same trick again (in >the same 4 years). Cassini would love to be able to launch on a direct trajectory to Saturn, or launch directly to Jupiter and use a gravity assist to get to Saturn. This is not possible due to the launch energy requirements of these trajectories. The launch vehicle currently baselined for Cassini, the Titan IV/SRMU/Centaur, can launch our total wet mass of over 5800 kg with a maximum C3 (launch V-infinity squared) of ~22 km^2/s^2. Compare this to the minimum C3 needed to reach Jupiter or Saturn directly (~83 for Jupiter, ~108 for Saturn for '97 launch) and you can see why we need to use indirect trajectories. Steve Flanagan Cassini Mission Design Team stevef@awolf.jpl.nasa.gov Standard disclaimers apply. ------------------------------ Date: 11 Dec 92 16:44:47 GMT From: "Michael F. Santangelo" Subject: DC info Newsgroups: sci.space henry@zoo.toronto.edu (Henry Spencer) writes: >In article mike@starburst.umd.edu (Michael F. Santangelo) writes: >> I'm real foggy from this description as to what the RL200 engine is >>going to be. Is it a name for many RL10-A5's grouped together through >>a common master nozzle of some form? Or is it a seperate engine system >>used to augment the RL10-A5's on the latter DC systems during flight...? >No, it's a new engine, with some RL10 design heritage, relying on bits and >pieces that mostly have been tested already. Only DC-X (and the proposed >DC-X' suborbital flyer) will use RL10s at all. It's an excellent engine, >but a bit small for the full-scale DC-Y. (Allen & Henry- thanks for the initial followups to my question) How different will the RL200 be from the RL10-A5's used on DC-X? Is it simply a scaled up version of the same (RL10). Better way to do this would perhaps be to post the (proposed) thrust, isp, etc specifications of the RL200 beside that of the RL10-A5 in a table. Allen Sherzer writes: >It is a separate engine which will be used for DC-Y if built. Some of the >RL-200 engines will have extendable nozzles and will be sustainer engines >for DCY and others will have non-extandable ones and will be used as >boosters. Except for the nozzles, they will be the same. How many RL200's would be used on the DC-Y/DC-1 designs? Boosters? on DC? I take it normal LEO operations would not require booster RL200s, but is this sort of a strap-on capability for larger payloads and/or more demanding orbital inclinations? -- -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Michael F. Santangelo + Internet: mike@cbl.umd.edu Computer & Network Systems Director + mike@kavishar.umd.edu UMCEES / CBL (Solomons Island) + BITNET: MIKE@UMUC University of Maryland + Voice: (410) 326-7237 (direct) + (410) 326-4281 x237 ------------------------------ Date: Fri, 11 Dec 92 16:39:43 GMT From: Doug Mohney Subject: DC vs Shuttle capabilities Newsgroups: sci.space In article <3kf2v=-@rpi.edu>, kentm@aix.rpi.edu (Michael V. Kent) writes: >In article <1992Dec10.151210.21951@iti.org> aws@iti.org (Allen W. Sherzer) writes: > >>In article kentm@aix.rpi.edu (Michael V. Kent) writes: > >>>Here's a question that just popped into my head: Would a modified Spacehab >>>(note the "h") module fit in the cargo bay of the Delta Clipper? > >>Why not just make it a module on the space station? > >I'm thinking more along the lines of modifying it into a man-tended free-flyer. >Delta Clipper's projected 2-day on-orbit time is too short for Spacehab >work, especially if you have a space station. There are some experiments >that would benefit from man-tended operations instead of space-station >operations. Umm, your better bet would be to launch your thingy on a unmanned expendible (you pick 'em, probably Allen's much vaunted Titan IV or Delta-whatever). Or an uprated Ariane, depending on how much working space/mass you wanted to lift, and how competitive the bids are. Or go over and waive some money at the Russians, get them to send up some surplus hardware they have laying around. DC-1, ***IF*** it lives up to its promise, opens up the doors for some of the bigger industrial conglomerates to (if they need/want it) send up their own tin cans for experimentation purposes. Or to rent space on Mir and access it at their own place. The Henry Spencer Industrial Space Park, anyone? :-) Play in the intelluctual sandbox of Usenet -- > SYSMGR@CADLAB.ENG.UMD.EDU < -- ------------------------------ Date: 11 Dec 92 20:40:50 GMT From: "Allen W. Sherzer" Subject: DoD launcher use Newsgroups: sci.space In article <1992Dec11.171055.24364@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>The current head of Space Command ran the air war against Iraq and was >>hampered by lack of access to satellite images. A vehicle with DC's >>turnaround time is just what he needs. >This puzzles me somewhat. DC would allow a short notice launch of a LEO >satellite, but such satellites have very short, and fixed, looks at a >given combat theatre. If would seem to me that recon aircraft are still >a better choice for tactical recon. for many applications satellite is better. Recon aircraft are too easy to shoot down (especially when doing Bomb Dammage Assessments). In addition, every aircraft in the theatre needs services for takeoff, landing, refueling, jamming, defense suppression, ATC, fighter cover, and others. Every recon sortie you fly looses you a sortie for CAP, bombing, or whatever. In addition, satellite images can be made available sooner and are far fresher than photos taken from aircraft. Aircraft DO have a role but rapid satellite deployment will make your air force a LOT more productive. >Using DC itself as a recon platform >seems like serious overkill, Not DC itself. DC simply launches the satellite. >but then the military always likes overkill I suppose. Sometimes. But then so would you if it was YOUR ass on the line getting shot at. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------134 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Sat, 12 Dec 92 16:27:20 EST From: John Roberts Subject: Jet Lag -From: 18084TM@msu.edu -Subject: Jet Lag -Date: 11 Dec 92 22:29:44 GMT ->I believe you have that backwards. My understanding is, the faster the ->flight, the less the jet lag. -Think about it. If you take a tramp steamer, the difference between your -local time and POD time is very small, per unit of travel time, so you -can catch up on the difference as you go. The faster you travel, the -bigger is that difference, and the less time, during travel, you have to -keep in-phase. I think I tend to agree with Henry's view (that faster travel shouldn't have a negative effect on time adaptation), with the following provisions: # Henry's approach requires that you spend a day or more either before or after the flight to adapt your schedule. In theory that makes sense, but in practice it is likely to take considerable mental discipline (which Henry has, no doubt, but I'm not so sure about the rest of the population). Before the trip, you're busy getting ready, taking care of last-minute details, etc. And if you have limited vacation time, it might seem silly to take an extra day of leave just to stay at home sleeping during the day. Once you get to your destination, the natural incliniation is to rush around doing things, rather than "waste" a day sleeping. A longer travel time *forces* you to start adjusting (with various unpleasant side effects, as Henry pointed out). # Many people tend to wake up at local dawn, regardless of how much sleep they got. So it might be necessary to put black paper over the bedroom window in order to adjust properly. # Humans are really only efficient at adjusting their sleep cycles forward - it's much easier to stay up a little later and sleep a little later than to go to bed earlier and get up earlier. So if the direction of travel is such that backward adjustment is required, the fatigue brought about by sitting for many hours in an uncomfortable seat might help you to sleep when you ordinarily would not. But I wouldn't say that this is a real benefit of prolonged travel time - it's more a *perceived* benefit. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 11 Dec 92 22:19:49 GMT From: Lord Vader Subject: Magellan Update - 12/11/92 Newsgroups: sci.space,sci.astro,alt.sci.planetary To Ron Baalke:(or anyone else who knows) re: >1. Magellan continues to operate normally, transmitting a carrier plus >40 bps X-band signal which is precisely tracked by the DSN (Deep Space Network >stations to provide gravity data. >2. The present command sequence is designed to automatically shift the >telemetry to the 1200 bps rate if the tracking pass is over a 70 m >station, based on the DSN station allocation schedule as of the time >the reference file was prepared. In the event the station assignment >is changed, some telemetry may be lost because the 34 m stations >cannot successfully receive the 1200 bps rate due to the Transmitter B >noise spur. Which DSN stations are 34 m and which are 70? Also, do some of the DSN stations have the capability to recieve S-band and X-band at the same time, and if so, which ones? And, who can I contact to get the parameters of the individual DSN stations and the entire DSN capabilites? I understand that Magellan has limited capability to transmit engineering data over the X-band transmitter due to the noise spur in the subcarrier. Is this data then being transmitted via the s-band, and if so, like I asked above, is it being recieved at the same time as the x-band gravity data, or does it have to be recieved separately due to limited ground capabilities? Mike ------------------------------ Date: Sat, 12 Dec 92 16:09:21 EST From: John Roberts Subject: NASA Select mission coverage -From: tffreeba@indyvax.iupui.edu -Subject: SSF Deputy Dir. Interview -Date: 12 Dec 92 18:27:45 GMT - This is a short piece on an interview I had with Martin Kress of - NASA. I am sorry if it is not very good but I whacked it out - when I should have been studying for finals. - Thomas Freebairn - Some of the problems he sees with NASA communications are the - over use of technical jargon and acronyms. - Kress would like to see a little English brought to NASA's video - feed, too. - "When you watch a mission on NASA Select, I would really like to - see a narrator who is not a scientist or an engineer to give a - narrative in simple terms," Kress said. They did a very good job of that on STS-53 - the acronyms and the projects they represented were explained many times. Another innovation was text periodically placed on the screen reading "next mission summary at