Tuesday, February 19, 2008

Space Shuttle Atlantis Homeward Bound to KSC, Landing Ahead of Falling Satellite Shootdown

After a highly successful mission to the International Space station, the crew of the Space Shuttle Atlantis is heading home to Kennedy Space Center. NASA is staffing both the KSC Shuttle Landing Strip and Mojave Desert facilities at Edwards Air Force Base in California in a bid to get Atlantis home before the U.S. Navy attempts to shoot down a crippled spy satellite.

Engineers are monitoring, but are not concerned about, a circuit failure that dropped heat to four after venier thrusters. Those thrusters power the Reaction Control System (RCS), which maneuvers the orbiter during small in-flight corrections.

The temperature on one of the thrusters dropped to 40 degrees, causing concern about possible freezing of lines or systems in that area. Even if one or two of the thrusters should totally fail--highly unlikely--the system has built-in redundancy because the crew can employ the thrusters in a variety of combinations.

Actual rocket firing to drop Atlantis into its come-home orbital path is done by the larger Orbital Maneuvering Systems ((OMS) pods. The thruster problem on the smaller rocket system does not impact the operation of the larger OMS engines.

Early this morning, mission controllers in Houston asked Mission Commander Steve Frick to swing the orbiter around so that its tail faced the sun. This common maneuver in effect put the RCS thrusters out for warming by the sun.

The primary Shuttle landing trajectory for 9:07 a.m. landing Wednesday at KSC's Runway 33 takes the Shuttle over Central America and the Gulf of Mexico before flying across Florida to Kennedy Space Center. That course will treat area residents to the double sonic boom that for decades has signalled the space shuttle coming home to the nation's spaceport.

STS-122 long-range landing track

STS-122 mid-range landing track

There are four landing opportunities Wednesday at KSC and Edwards, as follows with timelines including orbit numbers and de-orbit OMS engine firings (burns):

202...1st KSC OPPORTUNITY DEORBIT BURN........12/17:16...08:01 AM...13:01
203...1st KSC OPPORTUNITY LANDING.............12/18:22...09:07 AM...14:07

203...2nd KSC OPPORTUNITY DEORBIT BURN........12/18:52...09:37 AM...14:37
204...2nd KSC OPPORTUNITY LANDING.............12/19:57...10:42 AM...15:42

204...1st EDW AFB OPPORTUNITY DEORBIT BURN....12/20:22...11:07 AM...16:07
205...1st EDW AFB OPPORTUNITY LANDING.........12/21:27...12:12 PM...17:12

205...2ND EDW AFB OPPORTUNITY DEORBIT BURN....12/21:58...12:43 PM...17:43
206...2ND EDW AFB OPPORTUNITY LANDING.........12/23:02...01:47 PM...18:47

The Atlantis crew delivered the European Space Agency module to the ISS. Commander Steve Frick, pilot Alan Poindexter, Leland Melvin, Stan Love, Rex Walheim, Hans Schlegel also ferried European Space Agency astronaut LĂ©opold Eyharts to the space station.

On the homeward bound trip they'll taxi NASA astronaut Dan Tani, who joined Space Station Commander Peggy Whitson and cosmonaut Yuri Malenchenko last October.

Tani, who flew to the ISS aboard Discovery, was due back on Earth in December. However, Atlantis' mission was delayed by by problems with fuel sensors. During his extended stay, Tani got the bad news that his 90-year-old mother had been tragically killed in a car wreck Dec. 19. It's the first time that an astronaut in space has had to be notified of a family member's death.

While in orbit, astronauts Love, Walheim and Schlegel, in varying teams, completed three arduous space walks. Schlegel had to miss his first space walk due to an unspecified illness, most likely a form of the dreaded space sickness--a former of super nausea much like car sickness, many times multiplied. In the space version, the inner ear loses the ability to stabilize the astronaut during adjustment to living in micro-gravity.

The crippled NROL-21 satellite will pass over an area west of Hawaii at about 10:30 p.m. EST Wednesday. Pilots have been notified to stay clear of that area, declared restricted. It's not yet known if the Navy will attempt the first-ever rocket shootdown of a decaying satellite, which will otherwise impact Earth sometime in March.

The satellite's location can be checked at Heavens Above.Its orbital designation is USA 193.


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