Astronaut Jeff Williams turned over command of the International Space Station to cosmonaut Oleg Kotov early Wednesday, setting the stage for Williams and flight engineer Maxim Suraev to undock and return to Earth on Thursday.

Williams and Suraev, who will command the Soyuz TMA-16 spacecraft for the trip home, plan to undock from the lab complex at 4:03 a.m. EDT Thursday, leaving the space station in the hands of Expedition 23 commander Kotov, Japanese astronaut Soichi Noguchi and NASA flight engineer Timothy Creamer.

A four-minute 18-second deorbit rocket firing at 6:34 a.m. will slow the Russian ferry craft enough to drop it back into the atmosphere for a landing in Kazakhstan at 7:24 a.m., 169 days, four hours and 10 minutes after launch from the Baikonur Cosmodrome on Sept. 30. Forecasters predicted temperatures in the low 20s, snow on the ground and gusty winds at the landing site near Arkalyk.

Here is a timeline of major re-entry events (in EDT and mission elapsed time):

EDT...........DDD...HH...MM...SS...EVENT

3/18
03:00:00 AM...168...23...45...18...Station orientation under Russian control
03:22:02 AM...169...00...07...20...Sunrise
03:30:00 AM...169...00...15...18...Station maneuvers to undocking orientation
03:59:00 AM...169...00...44...18...Station is in free drift
04:00:00 AM...169...00...45...18...Undocking command

04:03:00 AM...169...00...48...18...UNDOCKING

04:06:00 AM...169...00...51...18...Soyuz separation burn No. 1
04:08:00 AM...169...00...53...18...ISS maneuvers to duty attitude
04:17:55 AM...169...01...03...13...Sunset
05:10:00 AM...169...01...55...18...Station orientation returns to U.S. control
06:25:01 AM...169...03...10...19...Sunrise
06:34:05 AM...169...03...19...23...Soyuz deorbit burn begins (dV: 258 mph)
06:38:23 AM...169...03...23...41...Soyuz burn complete
07:01:19 AM...169...03...46...37...Atmospheric entry
07:09:42 AM...169...03...55...00...Parachute deploy command

07:24:42 AM...169...04...10...00...LANDING

If all goes well, the Soyuz will dock at the new Poisk module at 1:28 a.m. on April 4. The next day, NASA hopes to launch the shuttle Discovery on a three-spacewalk assembly and resupply mission, with docking at the forward Harmony module on tap around 3:50 a.m. on April 7.

Early Wednesday, Williams turned over command of the space station to Kotov, bringing an end to Expedition 22.

"I would like to thank the crew here for supporting me and for actually being really autonomous," Williams said. "I mean, I didn't have to do anything, everyone is a self starter here, everyone did a good job in everything that came before us, well beyond things that were asked."

Williams thanked Kotov, veteran of a previous long-duration stay aboard the station, saying "you came with a lot of experience, you made great contributions from end to end of the space station ... and even through today, I continue to take your advice on things and (learn) new things from you. Thank you for that.

"T.J. and Soichi, you guys have done great," Williams said. "Soichi, it's your second flight, your first long-duration flight, and I would like to congratulate you. You're off to a great start, you really took charge of the (Japanese) Kibo facility and really across the U.S. segment. You've been a pleasure to work with and you have represented Japan very well. So congratulations to you and thank you for your great work."

Williams gave Creamer, a fellow Army aviator, a gold astronaut pin marking his status as a veteran space flier, along with an Army aviation award.

"T.J., I know you waited a long time for this flight and you are a natural up here," Williams said. "I congratulate you, that's especially important to me being a fellow Army aviator. ... You've also been a great pleasure to work with and Max and I leave the station in good hands with you."

He then thanked Suraev, saying the cosmonaut's performance during his first flight had prepared him for a future mission.

"But first, don't think about that, we'll go home and join our families and take a break that is deserving of our families," Williams said. "Speaking of our families, they are the ones that are sometimes not thought of by everybody, but they're also the ones that probably make the greatest sacrifices. And all of us here have a family behind us that's especially important to us. So I would like, on behalf of the entire crew, to thank the families and the support and the sacrifices that they have made."

Kotov spoke briefly, praising Williams for demonstrating "excellent leadership and a good example, being an excellent commander. Thank you for leaving station in such excellent condition. We'll try (to) keep it in good shape. Thank you, Jeff, thank you, Max, and Godspeed."

Williams then formally turned over command of the station to Kotov, saying "I stand relieved. Congratulations."