Atlantis crew preps for entry

Keeping tabs on the weather, the Atlantis astronauts are preparing for re-entry and landing today at the Kennedy Space Center to close out the shuttle's 32nd and final flight.

Commander Kenneth Ham and his five crewmates have two Florida landing opportunities, the first around 8:48:14 a.m. EDT and the second at 10:22:58 a.m. Forecasters are predicting a chance for showers within 30 nautical miles of the runway for both opportunities, a violation of NASA's flight rules, and brisk winds out of the northwest.

But so far, off shore showers are staying out over the water and flight controllers are cautiously optimistic about getting Atlantis back to Earth later this morning.

"You got any advance intel on how the moisture's looking at the Cape?" Ham asked early today.

"Well, as you can imagine, we've been staring at the same radar screen for a couple of hours," astronaut Charles Hobaugh replied from mission control in Houston. "And it's actually looking pretty favorable. There are some spotty showers that are out over the water that are north, headed south, a chance of showers within 30 miles, but we think we'e got a pretty good fighting chance."

"Okey doke. 50-50," Ham quipped.

"That's right. Hopefully we're on the good side of that 50."

The first landing opportunity calls for a deorbit rocket firing at 7:41:59 a.m., a three-minute 10-second burn using the shuttle's twin orbital maneuvering system rockets to slow the craft by about 233 mph.

After a half hour free fall, Atlantis would plunge back into the discernible atmosphere 76 miles above the south Pacific Ocean at 8:16 a.m. The flight path would carry the ship across Central America and western Cuba before a steep descent up the Florida peninsula to the Kennedy Space Center.

Taking over manual control at an altitude of about 50,000 feet above the spaceport, the current plan calls for Ham to guide Atlantis through a sweeping 317-degree right overhead turn to line up on runway 33.

If the weather prevents an on-time descent, Ham, pilot Dominic "Tony" Antonelli and their crewmates - flight engineer Michael Good, Stephen Bowen, Piers Sellers and Garrett Reisman - can try again one orbit later.

The second opportunity requires a deorbit rocket firing around 9:17:24 a.m., setting up a landing at 10:22 a.m.

Atlantis has enough on-board supplies to remain in orbit until Saturday in a worst-case scenario. As a result, NASA is not staffing its backup landing site at Edwards Air Force Base, Calif., Wednesday or Thursday. If Atlantis isn't back on the ground by Thursday, however, Edwards will be staffed for a Friday attempt.

Here are timelines for both Wednesday landing opportunities at the Kennedy Space Center (in EDT; best viewed with fixed-width font):

Opportunity No. 1: Rev. 186 Deorbit to KSC

  • Deorbit ignition: 07:41:59 AM (dV: 233 mph; dT: 3:10)
  • Crossrange: 679 miles
  • Range from atmospheric entry to KSC: 5,021 miles
  • Turn angle: 317-degree right turn to runway 33
  • Landing: 08:48:14 AM

  • Ground tracks for the shuttle Atlantis' first landing opportunity
    Wednesday. (Credit: NASA TV)


    12:20 AM......Crew wakeup
    03:41 AM......Begin deorbit timeline
    03:56 AM......Radiator stow
    04:06 AM......Mission specialists seat installation
    04:12 AM......Computers set for deorbit prep
    04:16 AM......Hydraulic system configuration
    04:41 AM......Flash evaporator cooling system checkout
    04:47 AM......Final payload deactivation
    05:01 AM......Payload bay doors closed
    05:11 AM......Mission control 'go' for OPS-3
    05:21 AM......OPS-3 entry software transition
    05:46 AM......Entry switch list verification
    05:56 AM......Deorbit maneuver update
    06:01 AM......Crew entry review
    06:16 AM......Commander, pilot don entry suits
    06:33 AM......Inertial measurement unit alignment
    06:41 AM......Commander, pilot strap in; others don suits
    06:58 AM......Shuttle steering check
    07:01 AM......Hydraulic system prestart
    07:08 AM......Toilet deactivation

    07:21 AM......Mission control 'go' for deorbit burn
    07:27 AM......Astronauts strap in
    07:36 AM......Single hydraulic power unit start

    07:41:59 AM...Deorbit ignition
    07:45:09 AM...Deorbit burn complete

    08:16:28 AM...Entry interface
    08:21:26 AM...1st roll command to left
    08:34:47 AM...1st roll left to right
    08:35:14 AM...C-band radar acquisition
    08:41:43 AM...Velocity less than mach 2.5
    08:43:56 AM...Velocity less than mach 1
    08:44:09 AM...Right turn to runway 33
    08:48:14 AM...Landing

    Opportunity No. 2: Rev. 187 Deorbit to KSC

  • Deorbit ignition: 09:17:24 AM (dV: 233 mph; dT: 3:10)
  • Crossrange: 360 miles
  • Range from atmospheric entry to KSC: 5,055 miles
  • Turn angle: 280-degree right turn to runway 33
  • Landing: 10:22:58 AM

  • Ground tracks for the shuttle Atlantis' second landing opportunity
    Wednesday. (Credit: NASA TV)


    08:57 AM......MCC 'go' for deorbit burn
    09:03 AM......MS seat ingress
    09:12 AM......Single APU start

    09:17:24 AM...Deorbit ignition
    09:20:34 AM...Deorbit burn complete

    09:51:15 AM...Entry interface
    09:56:11 AM...1st roll command to right
    10:06:31 AM...1st right to left roll reversal
    10:09:58 AM...C-band radar acquisition
    10:16:28 AM...Velocity less than mach 2.5
    10:18:41 AM...Velocity less than mach 1
    10:19:12 AM...Right turn to runway 33
    10:22:58 AM...Landing