Second try at space station reboost goes better
BY JUSTIN RAY
Posted: December 4, 2006
The Russian cargo freighter attached to the back of the International Space Station fired its engines for an altitude reboost maneuver this afternoon. The planned 23-minute burn began at 4:36 p.m. EST.
Flight controllers reported the maneuver appeared to be a success, adjusting the station's orbit to permit space shuttle Discovery the luxury of performing the desired rendezvous profile no matter what day the ship blasts off during the next couple of weeks.
NASA needs Discovery to reach the outpost on flight day 3. The station's orbit prior to today's reboost would have forced a rendezvous trajectory resulting in docking on flight day 4 if Discovery launched on even-numbered days.
Mission managers want every possible chance to get the shuttle launched before the end of 2006, yet avoid the day-later Discovery arrival because it wastes a day in the mission before even reaching the station.
A reboost attempt last week was aborted about three minutes into the maneuver because onboard computers sensed the station was yawing, ever so slightly, out of the proper orientation. Engineers determined the situation was due to the unbalanced configuration of the outpost since the new solar array wings were installed on the port side of the station truss structure in September. A software patch was uplinked to the freighter's computer to reset the allowable amount of drift for today's try.
The burn by the Progress 23P spacecraft latched to the aft port of the station's Zvezda module has placed the complex in a 219.5 by 205.9 statute mile orbit. The orbit was raised about 9 statute miles at apogee and 1.1 miles at perigee. Discovery can launch into this orbit from December 7 through 23, and also on Christmas Day, and achieve a flight day 3 docking.
Meanwhile, activities remain on schedule at the Kennedy Space Center for tonight's activation of the shuttle launch countdown. The launch team will gather in Firing Room 4 at 10:30 p.m. for the traditional "call to stations" in advance of starting the count. Clocks will commence ticking at 11 p.m.
There are no significant technical problems being reported with Discovery, and liftoff is still targeted to occur a few seconds before 9:36 p.m. EST Thursday night.