NASA, Russians mull launch dates for Atlantis, Soyuz http://spaceflightnow.com/shuttle/sts121/060714sts115soyuz/
BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: July 14, 2006 NASA and the Russian space agency are discussing launch options that almost certainly will shorten the launch window for the agency's next shuttle flight. It now is expected to open Aug. 27 or 28 and may close a week or so earlier than planned because of a requirement to provide time for the station crew to sleep shift between the departure of a U.S. space shuttle and the arrival of a Russian Soyuz capsule. Based on a photo documentation requirement to launch Atlantis on the next shuttle mission in daylight - and to ensure external tank separation in daylight - NASA had been planning on a launch window that opens Aug. 28 and closes Sept. 13. But the Russians are scheduled to launch the next full-time station crew aboard a Soyuz capsule Sept. 14, docking two days later. Joint U.S. and Russian flight rules require a separation between the departure of a shuttle and the arrival of a Soyuz to give the station crew time to adjust their body clocks for different sleep shifts and to make necessary preparations. If the shuttle launch was delayed until the end of the original window - Sept. 13 - and if the Russians tried to stick with their original launch date - Sept. 14 - the Soyuz would arrive at the station while the shuttle was still there, boosting the combined crew to 12, violating long-standing agreements and greatly complicating the shuttle crew's space station assembly work. If Atlantis took off Sept. 13 and the Russian delayed the Soyuz until after undocking, launching the next station crew no earlier than Sept. 24, re-entry and landing of the outgoing station crew would occur Oct. 4, long before sunrise in the Kazakhstan landing zone. The Russian recovery team includes new personnel for this flight and space managers do not want the new team to face a nighttime landing and recovery operation the first time around. To resolve the potential conflict, U.S. and Russian space managers are discussing options that would shorten the shuttle launch window and delay the Soyuz launch to Sept. 18 or 20. On board will be Expedition 14 commander Michael Lopez-Alegria, Soyuz commander Mikhail Tyurin and Japanese space tourist Daisuke Enomoto. Assuming a launch on Sept. 20, the Soyuz would dock Sept. 22 and the outgoing station crew - Expedition 13 commander Pavel Vinogradov, Jeff Williams and Enomoto - would return to Earth Sept. 30. While re-entry would occur in pre-dawn darkness in Kazakhstan, the sun would rise in time for recovery crews to do the bulk of their work in daylight. Backing up from a Soyuz launch on Sept. 20, Atlantis must undock by Sept. 19. That means launch cannot occur any later than Sept. 9. For a Soyuz launch on Sept. 18, Atlantis must be off the pad by Sept. 7. Shuttle program manager Wayne Hale has formally asked the Air Force Eastern Range for an Aug. 28 launch slot for Atlantis. In an interview with CBS News, Hale said he has asked shuttle managers to look into whether the flight could be moved up a day or so to add a bit more cushion to the front end of the launch window. "We have four or five days of contingency (time in Atlantis' processing schedule) right now, which is less than what historically we've needed," Hale said. "But based on a really outstanding performance by the Kennedy folks, there's some probability we would have four or five days where the vehicle's out at the pad and we could launch earlier. "So I have asked the imagery folks to take a look again at the predicted lighting, and it's not outside the realm of possibility when they run the lighting predictions with the final space station trajectory and so on and so forth, that the 27th might become available. That would ease a little bit the traffic model of the station." He said station program managers "have been talking very hard with their Russian partners about that." "The Russians really would like to kind of go pretty close to the schedule they've established, which doesn't leave a lot of room for weather days in Florida," Hale said. "So the earlier we can count down, the more likely we are to get off in time to deconflict the traffic." Assuming the Russians stick to their guns and only delay the Soyuz launch by a few days, Atlantis' crew will lose a week or so off the back end of their launch window. And if Atlantis isn't off the ground by the time the window closes, the next daylight launch opportunity will be a short window opening Oct. 26 and closing Oct. 29. At the Kennedy Space Center, engineers are readying Atlantis for rollout to the launch pad around Aug. 2. Work is already underway to address a handful of minor problems seen during Discovery's current flight, including replacement of additional gap fillers on the shuttle's belly and replacement of insulation blanket patches. Engineers say any additional inspections or work required because of problems experienced by Discovery's hydraulic power system can be accomplished at the launch pad. A wild card is an apparent problem with the helium pressurization system aboard Discovery that is used to operate main engine valves and to flush left over propellant out of the system after main engine cutoff - MECO - in orbit. Engineers studying data from Discovery's launch noticed an eight- to 10-pound-per-square-inch shift in the helium pressure used to purge main engine No. 3 after MECO. That shift was considered "to be of note and caused them some concern there might be a blocked filter or a check valve or something else," Hale said. The issue did not affect the performance of engine No. 3 but the helium system is used to control the operation of the powerplants and engineers want to make sure whatever caused the purge problem is not something potentially more serious. Hale said Discovery's engines will be removed shortly after landing to permit detailed tests and inspections. As of this writing, however, there are no indications of any similar problems aboard Atlantis. Gregory S. Williams [EMAIL PROTECTED] Reply with a "Thank you" if you liked this post. _____________________________ MEDIANEWS mailing list [email protected] To unsubscribe send an email to: [EMAIL PROTECTED]
