phil@Rice.edu (William LeFebvre) (05/01/89)
Since STS-30 didn't go off as planned, and since it now looks like it won't go until next week, I finished typing in the rest of the launch window times and am now posting it here. This table includes all the windows, even those that we have missed and are about to miss. A note about accuracy: this was accurate as of March 9 (that's the date on the chart), but they keep changing things around. For example, the April 28 window was, at some point, extended to 23 minutes. So take this for what it's worth. Open and close times are given in Central Daylight Time. To convert to GMT, add 5 hours. Window duration is given in minutes. Date Open Close Duration 4/28 13:24 13:42 18 4/29 13:18 13:43 25 4/30 13:13 13:44 31 5/ 1 13:07 13:45 38 5/ 2 13:01 13:45 44 5/ 3 12:54 13:46 52 5/ 4 12:48 13:47 59 5/ 5 12:42 13:48 66 5/ 6 12:35 13:49 74 5/ 7 12:28 13:49 81 5/ 8 12:21 13:50 89 5/ 9 12:11 13:51 100 5/10 12:02 13:51 109 5/11 11:59 13:52 113 5/12 11:53 13:53 120 5/13 11:46 13:47 121 5/14 11:38 13:39 121 5/15 11:31 13:32 121 5/16 11:23 13:24 121 5/17 11:15 13:16 121 5/18 11:07 13:08 121 5/19 10:59 13:00 121 5/20 10:51 12:52 121 5/21 10:42 12:43 121 5/22 10:34 12:35 121 5/23 10:25 12:26 121 5/24 10:17 12:18 121 5/25* 9:39 11:50 121 5/26* 9:29 11:30 121 5/27* 9:17 11:18 121 5/28* 8:59 11:00 121 * Contingency launch days Deply and landing are scheduled as follows: Event Orbit MET (D:H:M) Deploy 5 0:06:18 Landing 65 4:00:56 (MET = Mission Elapsed Time, counted from actual liftoff) William LeFebvre Department of Computer Science Rice University <phil@Rice.edu>
iiit-sh@cybaswan.UUCP (Steve Hosgood) (05/05/89)
In article <3205@kalliope.rice.edu> phil@Rice.edu (William LeFebvre) writes: >This table includes all the windows, even those that we have missed and >are about to miss. A note about accuracy: this was accurate as of >March 9 ....... > >Date Open Close Duration > >4/28 13:24 13:42 18 >4/29 13:18 13:43 25 >4/30 13:13 13:44 31 >5/ 1 13:07 13:45 38 >5/ 2 13:01 13:45 44 >5/ 3 12:54 13:46 52 >5/ 4 12:48 13:47 59 [They're off! (just caught close of window)] >5/ 5 12:42 13:48 66 >5/ 6 12:35 13:49 74 >5/ 7 12:28 13:49 81 >5/ 8 12:21 13:50 89 >5/ 9 12:11 13:51 100 >5/10 12:02 13:51 109 >5/11 11:59 13:52 113 >5/12 11:53 13:53 120 >5/13 11:46 13:47 121 From here on, the window length is 121 minutes. I presume the windows mentioned above *would* have been 121 minutes too, but got chopped short by sunset over at the across-the-atlantic abort sites? In the April dates, the windows open 5 minutes earlier each day. By mid-May, this has extended to sometimes 10 minutes a day. Why is this please? Also, I notice that it's not a constant slippage, between May 10 & May 11 it's only a 3-min difference, between May 8 & May 9 its 10 minutes etc. I could understand that if the mission had to be launched so as to catch a given sidereal time, then the window would slip by about 4 minutes a day. This evidently isn't the case here, is it a case of launching so that the Sun - Venus - Earth angle is the same each time or what? Info appreciated! Thanks in Advance. Steve -----------------------------------------------+------------------------------ Steve Hosgood BSc, | Phone (+44) 792 295213 Image Processing and Systems Engineer, | Fax (+44) 792 295532 Institute for Industrial Information Techology,| Telex 48149 Innovation Centre, University of Wales, +------+ JANET: iiit-sh@uk.ac.swan.pyr Swansea SA2 8PP | UUCP: ..!ukc!cybaswan.UUCP!iiit-sh ----------------------------------------+------------------------------------- My views are not necessarily those of my employers!
henry@utzoo.uucp (Henry Spencer) (05/10/89)
The latest issue of World Spaceflight News (US/Canada $35/12, elsewhere $50/12, airmail everywhere; Box 98, Sewell NJ 08080-0098 USA; a superb source of technical detail on shuttle missions, with a counterpart ["Planetary Encounter"] on planetary missions) includes the launch-window chart for the Magellan mission. The chart has time of day ascending up the vertical and date ascending rightward on the horizontal. The window is primarily a broad stripe running down from upper left to lower right. The stripe cuts off at April 24 on the left and May 23 on the right, which looks like something like energy requirements for the Venus trajectory. [WSN unfortunately didn't print a detailed *explanation* of the chart!] There is also a nearly-horizontal line running across, sloping slightly upward to the right, above which the lighting at Trans-Atlantic-Abort sites is unacceptable. So the window opens when the stripe crosses the line on about April 28, and reaches full width about May 10. The boundaries of the stripe are fuzzy, with several contours marked "yaw steering", which I assume means that launches near the boundaries of the window require extra shuttle maneuvering to get into the desired parking orbit. (The amounts, in pounds, given for the contours are too big to be Magellan's own fuel.) Finally, although the stripe is almost straight, from about May 8 to May 12 both boundaries bend downward and then recover; this is marked "perturbation due to Moon". Magellan itself also preferred a slight launch delay, because maximum economy on the injection into the desired Venus orbit required leaving Earth orbit after about May 3. (It is possible that this is the "yaw steering", if somebody has misplaced some decimal points and if one edge of the stripe is interpreted as negative and the other as positive.) This is mentioned in the text. -- Mars in 1980s: USSR, 2 tries, | Henry Spencer at U of Toronto Zoology 2 failures; USA, 0 tries. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu