Atlantis astronauts are approaching their final full day of space before the shuttle program's last landing, planned at 5:56 a.m. Thursday.
On Wednesday, the crew will pack equipment and test critical systems needed to control the orbiter's re-entry and landing.
One of three Auxiliary Power Units will be powered up to maneuver hydraulically controlled wing elevons, the body flap and rudder/speed brake. Those aerosurfaces will take over Atlantis' flight as it glides through the atmosphere.
Forty-four nose and tail steering thrusters used during re-entry will also be pulsed to ensure they're functioning properly.
And the crew should get word that orbiter heat shields have been cleared for re-entry after an inspection performed today.
Another key milestone Wednesday: deployment of the 180th satellite from a shuttle, a small, eight-pound pico-satellite carrying solar cell experiments for the Department of Defense.
The crew will perform its final in-flight interviews with national networks and later stow the Ku-band antenna that transmits television signals to the ground.
Here's a look at the highlights of the day ahead (times Eastern):
9:59 p.m. Tuesday: Atlantis crew awakes to begin Flight Day 13
1:14 a.m. Wednesday: Cabin stowage begins
2:14 a.m.: Checkout of flight control surfaces
3:54 a.m.: Picosat deployment
4:04 a.m.: Hot-fire of Reaction Control System steering jets
4:44 a.m.: Live interviews with ABC News, CBS News, CNN, Fox News, NBC News
8 a.m.: Mission status briefing
11:39 a.m.: Ku-band antenna stowed
1:59 p.m.: Crew sleeps
9:59 p.m.: Crew awakes, prepares for landing