Countdown to Landing: Atlantis Crew Headed Home

The distinctive twin sonic booms as Space Shuttle Atlantis streaked across the Florida sky told residents that the STS-122 crew was close to home. The textbook landing ended a 5.3 million mile expedition, the ferrying of a replacement astronaut, and the delivery of the Columbus module to the International Space Station.

With a successful mission completed, the crew of the Space Shuttle Atlantis is checking off the timelines and tasks before a scheduled 9:07 a.m. EST landing at Kennedy Space Center in Florida.

The team, including NASA astronaut Dan Tani, returning after an extended stay at the International Space Station, is scooting home before the U.S. attempts to shoot down a failing satellite. The first attempt could occur tonight off Hawaii, where a designated "no-fly" zone has already been declared. NASA officials wanted to clear space before that attempt and signalled the shuttle home today.

The shuttle has four landing opportunities in Florida and at Edwards Air Force Base in California. Here's the schedule for all four.

06:34:54 AM...Commander/pilot don entry suits
06:51:54 AM...Inertial measurement unit alignment
06:59:54 AM...Commander/pilot strap in; others don suits
07:16:54 AM...Shuttle steering check
07:19:54 AM...Hydraulic power system prestart
07:26:54 AM...Toilet deactivation
07:34:54 AM...Payload bay vent doors closed for entry
07:39:54 AM...MIssion control 'go' for deorbit burn
07:45:54 AM...Mission specialists seat ingress
07:54:54 AM...Single hydraulic power unit start

07:59:54 AM...Deorbit ignition (dV: 197.7 mph; dT: 02:39)
08:02:33 AM...Deorbit burn complete (altitude: 211.6 sm)

08:35:59 AM...Atmospheric entry (altitude: 75.6 sm)
08:40:59 AM...1st roll command to left
08:52:05 AM...1st left-to-right roll reversal
08:54:00 AM...C-band radar acquisition
09:01:06 AM...Velocity less than mach 2.5 (altitude: 84,200 feet)
09:03:18 AM...Velocity less than mach 1 (altitude: 50,700 feet)
09:03:42 AM...Shuttle banks 301 degrees to line up on runway 33
09:07:39 AM...Landing

SECOND FLORIDA OPPORTUNITY: Rev. 203 Deorbit to Kennedy

09:15:20 AM...Mission control 'go' for deorbit burn
09:21:20 AM...MS seat ingress
09:30:20 AM...Single APU start

09:35:20 AM...Deorbit ignition (dV: 195.7 mph; dT: 02:38)
09:37:58 AM...Deorbit burn complete (altitude: 214.5 sm)

10:11:00 AM...Entry interface (altitude: 75.6 sm)
10:15:57 AM...1st roll command to right
10:27:46 AM...1st right-to-left roll reversal
10:36:05 AM...Velocity less than mach 2.5 (altitude: 84,700 feet)
10:38:18 AM...Velocity less than mach 1 (altitude: 50,200 feet)
10:38:55 AM...Shuttle banks 269 degrees to line up on runway 33
10:42:35 AM...Landing

FIRST CALIFORNIA OPPORTUNITY: Rev. 204 Deorbit to Edwards Air Force Base, Calif.

10:45:15 AM...MCC 'go' for deorbit burn
10:51:15 AM...MS seat ingress
11:00:15 AM...Single APU start

11:05:15 AM...Deorbit ignition (dV: 195.7 mph; dT: 2:38
11:07:53 AM...Deorbit burn complete (altitude: 213.4 sm)

11:41:01 AM...Entry interface (altitude: 75.6 sm)
11:46:00 AM...1st roll command to left
11:55:55 AM...1st left-to-right roll reversal
12:06:06 PM...Velocity less than mach 2.5 (altitude: 81,800 feet)
12:08:19 PM...Velocity less than mach 1 (altitude: 49,400 feet)
12:09:24 PM...Shuttle banks 205 degrees to line up on runway 22
12:12:31 PM...Landing

SECOND CALIFORNIA OPPORTUNITY: Rev. 205 Deorbit to Edwards

12:21:25 PM...MCC 'go' for deorbit burn
12:27:25 PM...MS seat ingress
12:36:25 PM...Single APU start

12:41:25 PM...Deorbit ignition (dV: 195.7 mph; dT: 02:38)
12:44:03 PM...Deorbit burn complete (altitude: 216.9 sm)

01:16:09 PM...Entry interface (altitude: 75.6 sm)
01:21:06 PM...1st roll command to right
01:32:39 PM...1st right-to-left roll reversal
01:41:10 PM...Velocity less than mach 2.5 (altitude: 82,700 feet)
01:43:25 PM...Velocity less than mach 1 (altitude: 48,800 feet)
01:44:34 PM...Shuttle banks 189 degrees to line up on runway 22
01:47:34 PM...Landing