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 ; Wed, 7 Mar 90 01:27:22 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 7 Mar 90 01:26:49 -0500 (EST) Subject: SPACE Digest V11 #119 SPACE Digest Volume 11 : Issue 119 Today's Topics: Re: More info on Pegasus Re: More info on Pegasus Comet Austin Graph ---------------------------------------------------------------------- Date: 6 Mar 90 16:37:53 GMT From: usc!cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: More info on Pegasus In article <1990Mar6.111802.8379@agate.berkeley.edu> gwh@OCF.Berkeley.EDU (George William Herbert) writes: >Pegasus was origionally scheduled to fly before christmas. This was delayed >after problems mating the rocket to the B-52 were discovered in flight tests. >First launch is expected in the next month. It should be noted that there >have been no delays due to the rocket itself... Well, be fair now: it was *originally* scheduled to fly last summer. The B-52 integration problems caused part of the slip to Christmas, and since then they've been fighting an assortment of minor problems with materials and electronics (both in the support gear and on Pegasus itself). -- MSDOS, abbrev: Maybe SomeDay | Henry Spencer at U of Toronto Zoology an Operating System. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 6 Mar 90 11:18:02 GMT From: agate!headcrash.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Re: More info on Pegasus In article <1990Mar6.013334.13771@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > >Payload size is somewhat under 1000 lbs, as I recall; I can probably dig >up a more precise number if it's needed (and nobody beats me to it). It Pegasus is a three-stage winged [first stage] solid rocket able to launch 600 lbs into a 250nm polar orbit or 900 lbs into a 250nm equitorial orbit. The vehicle itself is 49.2 feet long, with a diameter of 48 inches and a wingspan of 22 feet. It weights 40,000 pounds at launch and is about the same shape and size as X-15 rocketplane, which was also launched from the B-52. The payload fairing is 46" diameter by 72" long. The launch costs are estimated at $8 million per launch, or about $10,000 per pound to orbit. This is unfavorable compared to other launchers on a per pound basis, but the small total cost remains attractive to those not needing large payloads. Pegasus was origionally scheduled to fly before christmas. This was delayed after problems mating the rocket to the B-52 were discovered in flight tests. First launch is expected in the next month. It should be noted that there have been no delays due to the rocket itself, and that the entire development program has been done in only twenty months including the delay, from concept to first flight. One program that has been developed alongside Pegasus is the Department of Defense lightsat program. The concept was for development of a number of small cheap easily-deployable sattelites for crisis situation use. Pegasus has already sold several test flights of lightsat prototypes to DOD. Another customer is a [Dutch?] firm that wanted to do a small low-orbit sattelite of one sort or another; they have the second or third launch, and were said to be happy with progress despite the flight delays. The launch profile follows: Launch is from the B-52 mothercraft, flying at 40 thousand feet and Mach 0.8 From here until the seperation of the first stage, the craft is controled by a set of aerodynamic control fins. Five seconds after release, the first stage ignites and the rocket begins a 2.5g pullup. At about fifty seconds into the flight the craft reaches max-q [maximum aerodynamic pressure on the rocket], at about 950 lbs/ft^2 force. After 81 seconds, the first stage burns out and seperates. At this point, the rocket is at 208,000 feet and moving at mach 8.7. The second stage is controled by a cold-gas reaction control system which takes over immediately after the first stage seperates. At 87 seconds into the flight, the third stage ignites, thrusting at an angle of 26 degrees above the horizon. At this point the craft is at 231,000 feet altitude. At the 120 second mark the payload fairing seperates from the craft. At 159 seconds the second stage burns out, with the craft at 552,000 feet and 17,800fps velocity. It is oriented 18.4 degrees above the horizon. The rocket now enters a coast phase, with no activity. When it reaches the 470 second point, the rocket is at 248nm altitude and 16,300fps velocity, with an angle of 1.9 degrees to the horizon. At this point the third stage ignites, and burns until 533 seconds, at which point the spacecraft is at 250 miles and 25,000fps velocity [orbital velocity]. Additional variants have already been proposed; DOD is funding a variant using the first stage of a MX missile to boost the rocket instead of using a B-52 launch. The reasoning is that this would make an excellent quick reaction light satelite launcher. ******************************************************************************* George William Herbert JOAT For Hire: Anything, Anywhere: My Price UCB Naval Architecture undergrad: Engineering with a Bouyant Attitude :-) ------------------------------------------------------------------------------- gwh@ocf.berkeley.edu |||||||||| "What do I have to do to convince you?"-Q gwh@soda.berkeley.edu |||||||||||||||||||||||||||||||||||||||| "Die."-Worf maniac@garnet.berkeley.edu |"Very good, Worf. Eaten any good books recently?"-Q ------------------------------ Date: 5 Mar 90 21:13:05 GMT From: elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@cs.ucla.edu (Ron Baalke) Subject: Comet Austin Graph I am posting this for Elwood Downey, as he seems to be having problems posting directly to the net. -------------------------------------------------------------------------- Here is a graph (that's putting it very politely, I admit) of my local rise and set times and a magnitude estimate of comet Austin for the period Mar 4 through May 18, UT. I also include my local times of dawn, sunrise, sunset and dusk for comparison, dawn and dusk meaning when the sun is about 18 degrees below the horizon. These are based on the orbital elements published in IAU circular 4941 and an "average" of several brightening models I have heard of. These were calculated for my local conditions (93:42:08W longitude, 44:50:37N latitude, 800 feet elevation 40 degrees F, 29.5in Hg). For other locations, a lower latitude can have several minutes effect. Plus you must correct for timezone and longitude or it might be easier to work with the differences from your local rise/set times. Or perhaps easiest of all is get a copy of ephem and run it yourself. Following the graphs, is the raw data. The calculations and the basic plots were done using ephem, v4.12 (recently submitted to comp.sources.misc). To read the graphs and the raw data table, use this key: A - austin rising D - dawn S - sunrise a - austin setting d - dusk s - sunset v - apparent visual magnitude When a character position collides in the graph, the key for austin always overrides. Magnitude graph: -2.4 vvvvvv vv vv vv vv v vv vv vvv v vvvvvv v v vv vv vvv 5 v | | | | | 3/4 3/22 4/9 4/28 5/18 Rise/Set graph: 0 A A 1 A A 2 A A D D 3 A D D D D D D D D D 4 D D D D D D D D D A A S S S S 5 D D D S A S S S S S S S S S S 6 S S S S S S S S A A A 7 A A 8 A A A 9 A A A 10 11 12 13 a 14 a 15 a 16 a 17 s s a 18 s s s s s s s s s s s s s s s s a a 19 a a a a a a a d a a s s s s s s s 20 a a a a a a a a a a d d d d 21 d d d d d 22 A A A 23 A A | | | | | 3/4 3/22 4/9 4/28 5/18 Raw data: (plot this with a tool you might have locally if at all possible) key,decimal year, value (in decimal utc hours, or magnitude for v) (same keys as graphs) A,1990.16986301,9.79083011615 a,1990.16986301,19.7657843298 D,1990.16986301,5.20525191138 S,1990.16986301,6.80019105975 s,1990.16986301,18.1041618529 d,1990.16986301,19.7025471894 v,1990.16986301,4.75684997358 A,1990.17808219,9.47737409017 a,1990.17808219,19.8174794894 D,1990.17808219,5.1160777999 S,1990.17808219,6.71142992846 s,1990.17808219,18.1707607101 d,1990.17808219,19.769777205 v,1990.17808219,4.33817047755 A,1990.18630137,9.1617266037 a,1990.18630137,19.8732456024 D,1990.18630137,5.02450615502 S,1990.18630137,6.62126171835 s,1990.18630137,18.2366313203 d,1990.18630137,19.8372805176 v,1990.18630137,3.88709133655 A,1990.19452055,8.84175711091 a,1990.19452055,19.9342835953 D,1990.19452055,4.93075038188 S,1990.19452055,6.52993986265 s,1990.19452055,18.301856795 d,1990.19452055,19.9051776442 v,1990.19452055,3.39928862575 A,1990.20273973,8.51476669761 a,1990.20273973,20.0019207748 D,1990.20273973,4.83503663937 S,1990.20273973,6.43772920627 s,1990.20273973,18.3665444357 d,1990.20273973,19.9736149285 v,1990.20273973,2.86958469006 A,1990.2109589,8.17754647556 a,1990.2109589,20.0774757273 D,1990.2109589,4.73758290605 S,1990.2109589,6.34488451512 s,1990.2109589,18.4307958348 d,1990.2109589,20.0427390772 v,1990.2109589,2.29282121104 A,1990.21917808,7.82585426413 a,1990.21917808,20.1622794926 D,1990.21917808,4.63858631192 S,1990.21917808,6.25164124358 s,1990.21917808,18.4946811524 d,1990.21917808,20.1126610844 v,1990.21917808,1.66395221789 A,1990.22739726,7.45408710189 a,1990.22739726,20.2574345536 D,1990.22739726,4.53823134411 S,1990.22739726,6.15822892979 s,1990.22739726,18.5582630276 d,1990.22739726,20.1834695519 v,1990.22739726,0.979996632609 A,1990.23561644,7.05479294213 a,1990.23561644,20.3633404935 D,1990.23561644,4.43670078301 S,1990.23561644,6.06486499185 s,1990.23561644,18.6215819125 d,1990.23561644,20.2552554938 v,1990.23561644,0.244081403565 A,1990.24383562,6.61806595579 a,1990.24383562,20.4786859071 D,1990.24383562,4.33417412075 S,1990.24383562,5.97176924707 s,1990.24383562,18.6846776216 d,1990.24383562,20.328098472 v,1990.24383562,-0.526358746461 A,1990.25205479,6.13203229802 a,1990.25205479,20.5982769854 D,1990.25205479,4.23082940694 S,1990.25205479,5.8791629885 s,1990.25205479,18.747582914 d,1990.25205479,20.4020732192 v,1990.25205479,-1.28389824329 A,1990.26027397,5.5850676661 a,1990.26027397,20.709762557 D,1990.26027397,4.12684496034 S,1990.26027397,5.78726214833 s,1990.26027397,18.8103371171 d,1990.26027397,20.477253668 v,1990.26027397,-1.93440341911 A,1990.26849315,4.9728696653 a,1990.26849315,20.7909306291 D,1990.26849315,4.02241808852 S,1990.26849315,5.69630416598 s,1990.26849315,18.8729831883 d,1990.26849315,20.5537295389 v,1990.26849315,-2.34577691652 A,1990.27671233,4.30866759787 a,1990.27671233,20.8131447502 D,1990.27671233,3.9177620275 S,1990.27671233,5.60654301327 s,1990.27671233,18.9355975802 d,1990.27671233,20.6316127751 v,1990.27671233,-2.42178482215 A,1990.28493151,3.62485363035 a,1990.28493151,20.7526475352 D,1990.28493151,3.8130990656 S,1990.28493151,5.51823390253 s,1990.28493151,18.9982430564 d,1990.28493151,20.7109988312 v,1990.28493151,-2.18772631224 A,1990.29315068,2.95958374338 a,1990.29315068,20.5991191881 D,1990.29315068,3.70865346389 S,1990.29315068,5.43163525724 s,1990.29315068,19.0609331399 d,1990.29315068,20.7919298976 v,1990.29315068,-1.76446836218 A,1990.30136986,2.34065196488 a,1990.30136986,20.353084435 D,1990.30136986,3.6046524706 S,1990.30136986,5.3469921399 s,1990.30136986,19.1236341584 d,1990.30136986,20.8743932326 v,1990.30136986,-1.27286422113 A,1990.30958904,1.78085298321 a,1990.30958904,20.0199818598 D,1990.30958904,3.50134161139 S,1990.30958904,5.26455872303 s,1990.30958904,19.1862901558 d,1990.30958904,20.9583292544 v,1990.30958904,-0.788544303151 A,1990.31780822,1.28096457073 a,1990.31780822,19.6052994387 D,1990.31780822,3.39897866051 S,1990.31780822,5.18458517905 s,1990.31780822,19.2487976357 d,1990.31780822,21.043623215 v,1990.31780822,-0.348157025252 A,1990.3260274,0.834158330876 a,1990.3260274,19.112053837 D,1990.3260274,3.29783723068 S,1990.3260274,5.10731680048 s,1990.3260274,19.3110089101 d,1990.3260274,21.1300937404 v,1990.3260274,0.034392771621 A,1990.33424658,0.430262527805 a,1990.33424658,18.5388467769 D,1990.33424658,3.19821689065 S,1990.33424658,5.03299234627 s,1990.33424658,19.3727561698 d,1990.33424658,21.2175044849 v,1990.33424658,0.355316453147 A,1990.34246575,23.9394943667 a,1990.34246575,17.8783255796 D,1990.34246575,3.10045848906 S,1990.34246575,4.9618794758 s,1990.34246575,19.4338622487 d,1990.34246575,21.3055865674 v,1990.34246575,0.615447885653 A,1990.35068493,23.5940426583 a,1990.35068493,17.1163756511 D,1990.35068493,3.00495923824 S,1990.35068493,4.8942556342 s,1990.35068493,19.4941499219 d,1990.35068493,21.3940410805 v,1990.35068493,0.817796006756 A,1990.35890411,23.2583741698 a,1990.35890411,16.2312273976 D,1990.35890411,2.91216252093 S,1990.35890411,4.83041102837 s,1990.35890411,19.5534406204 d,1990.35890411,21.4825173803 v,1990.35890411,0.967811882722 A,1990.36712329,22.9254947662 a,1990.36712329,15.1962276313 D,1990.36712329,2.82255157602 S,1990.36712329,4.77062957916 s,1990.36712329,19.6115133586 d,1990.36712329,21.5705761598 v,1990.36712329,1.07559995458 A,1990.37534247,22.5900504405 a,1990.37534247,13.9865276649 D,1990.37534247,2.73665976508 S,1990.37534247,4.71519142337 s,1990.37534247,19.668086992 d,1990.37534247,21.6576700902 v,1990.37534247,1.16135546782 Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ End of SPACE Digest V11 #119 *******************