Received the comment below about the upcoming STS-111 launch attempts and a bit more on Beta angle limitations to Shuttle/ISS docked operations. Source asked not to be named (not that it's a big deal -- just didn't want a flurry of E-mails!) In case you missed it, BETA angle is the angle between the Earth-Sun vector and the normal to a satellite's orbital plane. This dictates how much sunlight a vehicle receives per orbit. As Ted Molczan described to me, the Shuttle or ISS by themselves can operate at high Beta angles (more sunlight) since they can orient their radiators in an optimum manner (or in the case of the Shuttle, go into "barbeque" mode). But when the Shuttle is docked to ISS, one or the other cannot positions the radiators correctly, creating the limitation. Rick Baldridge ________________________________________________ I contacted the person at JSC in the mission operations directorate/TOPO for our flight. He gave me the Beta angle position for ISS for UF-2. The person who provided us the original information concerning beta angle and launch was himself given mis-information. The launch window for UF-2/STS-111 is May 30 to July 10. The original person was confused as to how to look at the beta angle matrix. The launch window will be more than the three daysmentioned. They are planning to do 9 launch scrub attempts if the first launch attempt is scrubbed. Remember,there is a difference between Launch scrub and delay before tanking. If there is a delay before tanking, it is considered a slip in the scheduled launch date, so there will be 9 launch scrub attempts available. If the launch is scrubbed, there will be 8 launch scrubs left. Since the launch window is not a factor, the idea of launching on Saturday or Sunday, in the event of a Friday delay or scrubb, will not be entertained, due to overtime pay costs, unless the weather will be degrading starting the following Monday and all subsequent days. Normally, they will try launching on Monday. Beta angle and its consequence is as Ted (Molczan) describes. The mission wouldn't be scrapped, just a slip in the launch date. When the Orbiter is in-flight (not docked to ISS) and it gets to a beta angle greater than 60 degrees, the Orbiter goes into "rotisserie" mode. In other words, it slowly rotates around its X-axis (nose to tail axis). For flights to ISS, the Shuttle can launch during an ISS Beta cutout, if and only if, ISS will be at a beta less than 60 degress at dock and throughout the docked phase. Therefore, the mission duration affects launch timing when the beta cutout dates are approaching. ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/sat/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Fri May 24 2002 - 15:01:20 EDT