All systems "go" for shuttle landing Tuesday

Endeavour's astronauts are on track to return Tuesday to Kennedy Space Center, and the weather looks as if it will acceptable for a lunchtime landing here at the shuttle's homeport.

With the threat from Hurricane Dean diminishing and testing on critical reentry systems now complete, the seven astronauts aim to touch down on KSC's three-mile shuttle runway at 12:32 p.m. EDT Tuesday.

Flying the spaceship tail-first and upside down, Endeavour mission commander Scott Kelly is scheduled to ignite the orbiter's twin maneuvering engines about 11:25 a.m.

The 3-minute, 33-second firing will slow the spaceship by 361 mph, just enough for Endeavour and its crew to begin dropping out of orbit. The shuttle and its five-man, two-woman crew will travel over the South Pacific before crossing over the southern tip of central America near the border between Costa Rica and Nicaragua.

Click to enlarge the long-range ground track for landing on Orbit No. 201:



















Hurricane Dean is expected to make landfall in the Yucatan Peninsula about three hours earlier. Click to enlarge the 11 a.m. Monday update from the National Hurricane Center in Miami:
















Even if the Category 4 storm were to stall under Endeavour's flight path, the shuttle would pass 180,000 feet above the hurricane as it traveled over central America and crossed out over the Caribbean Sea on its way back to its coastal Florida launch site.

Click on the midrange ground track here:



















Endeavour will pass over Cuba and the Gulf of Mexico before making landfall around Marco Island and passing near the eastern banks of Lake Okeechobee before traveling up the east coast of the Florida peninsula.

The shuttle's trademark twin sonic booms, as a result, should be much louder than normal as Endeavour crosses over the southern and central parts of Brevard County on its way in to the KSC runway.

Click to enlarge the close range ground track for Orbit 201:



















The Endeavour astronauts now are taking a few off-duty hours and will be heading off to sleep early this evening. Crew wake-up is scheduled at 4:36 a.m. Tuesday, and the astronauts will begin deorbit preparations about 7:26 a.m.

The shuttle's clam shell-like payload bay doors are to be closed around 8:45 a.m., and the astronauts will start donning their partial-pressure launch-and-entry suits about 10 a.m.

The "Go/No-Go" decision for deorbit burn is scheduled to take place about 11:07 a.m. but can be made anytime up until the scheduled 11:25 a.m. engine ignition.

There would be a second KSC landing opportunity at 2:06 p.m., and there are three subsequent opportunities to land at Edwards Air Force Base in California. But mission managers will opt to keep the shuttle in orbit an extra day if weather prevents a landing here at KSC.

The shuttle can remain in orbit until Friday, and managers would rather land in Florida to avoid the cost and time that would be involved with ferrying the orbiter back to KSC from the Mojave Desert military base.

You can check out the latest on landing opportunities on Tuesday, Wednesday and Thursday here: STS_118_Deorbit_Opportunities.doc.

The weather forecast for KSC, however, looks relatively good. There's a slight chance of rain showers within 30 nautical miles of the shuttle runway, but conditions are expected to be acceptable for landing.

The Spaceflight Meteorology Group at Johnson Space Center in Houston gave the following weather update to mission managers earlier today: STS118LANDINGWX.ppt.