Change of command ceremony sets stage for Soyuz landing Friday

Outgoing Expedition 24 commander Alexander Skvortsov handed over control of the International Space Station to Douglas Wheelock Wednesday in a change-of-command ceremony that sets the stage for the departure and return to Earth of Skvortsov, Mikhail Kornienko and Tracy Caldwell Dyson early Friday aboard a Russian Soyuz capsule.

"Today is great day for me," Skvortsov said in a televised downlink. "I am Alexander Skvortsov, colonel in the Russian air force, cosmonaut and commander of the International Space Station since May 2010. Today, I am honored to relinquish command to U.S. Army Col. Doug Wheelock."

"Thank you Sasha. With great honor I receive and accept command of the International Space Station from you," Wheelock replied. "Thank you."

Change of command aboard the International Space Station. Back row,
left to right: Fyodor Yurchikhin, Shannon Walker, Mikhail Kornienko
and Tracy Caldwell Dyson. Front row, left to right, Douglas Wheelock
and Alexander Skvortsov. (Photo: NASA TV)
"We are both pilots and have been flying together for three months aboard the International Space Station," Skvortsov said. "Our work is a good example of how working peacefully together we can accomplish great things."

Switching to Russian, Wheelock wished Skvortsov and his two Soyuz crewmates "best of luck. We will be looking forward to seeing you on the ground." He jokingly concluded, "we wish you a safe landing and most importantly, break a leg!"

Wheelock, NASA flight engineer Shannon Walker and cosmonaut Fyodor Yurchikhin will become the core members of the 25th expedition to the space station when Skvortsov, Kornienko and Caldwell Dyson depart Thursday aboard the Soyuz TMA-18 spacecraft that carried them into orbit last April 2.

Undocking from the Poisk compartment atop the Zvezda command module is targeted for 9:35 p.m. Thursday. After moving a safe distance away from the space station, Soyuz commander Skvortsov, assisted by Kornienko, plans to fire the spacecraft's braking rocket for four minutes and 21 seconds, starting at 12:04:23 a.m. Friday, to slow the Soyuz by about 258 mph and begin the descent to Earth.

Just before falling into the discernible atmosphere at 12:32 a.m., the three modules making up the Soyuz TMA-18 spacecraft will separate and the crew will continue the descent in the central control module.

Atmospheric entry will occur at an altitude of about 61.8 miles. A few seconds later, entry guidance will begin to maintain the proper trajectory to the planned landing site 90 miles southeast of Dzhezkazgan, Kazakhstan. Touchdown is expected around 12:55:44 a.m. (10:55:44 a.m. local time).

Wheelock, Walker and Yurchikhin will have the lab complex to themselves for about two weeks. Three fresh crew members -- cosmonauts Alexander Kaleri, Oleg Skripochka and former shuttle commander Scott Kelly -- are scheduled for launch from the Baikonur Cosmodrome in Kazakhstan Oct. 7 aboard an upgraded Soyuz TMA-01M spacecraft. Docking is expected two days later.

Here is a timeline of major events in the Soyuz TMA-18 re-entry (in EDT and mission elapsed time; best viewed with fixed-width font):
DATE/EDT......DDD...HH...MM...SS...EVENT

9/23
07:56:00 PM...174...19...51...26...Russian thrusters disabled
08:12:00 PM...174...20...07...26...Russian thrusters enabled
08:30:00 PM...174...20...25...26...US to Russian attitude control handover
09:01:00 PM...174...20...56...26...ISS maneuvers to undocking attitude
09:11:53 PM...174...21...07...19...Sunrise
09:17:00 PM...174...21...12...26...Sunrise at Landing Site
09:29:37 PM...174...21...25...03...Daily Orbit 14 Russian ground station AOS
09:31:00 PM...174...21...26...26...ISS to free drift
09:32:00 PM...174...21...27...26...Undocking command
09:35:00 PM...174...21...30...26...Physical separation
09:38:00 PM...174...21...33...26...Soyuz separation burn (15 sec, 1.4 mph)
09:40:00 PM...174...21...35...26...ISS maneuvers to duty attitude
09:47:08 PM...174...21...42...34...Daily Orbit 14 Russian ground station LOS
10:13:58 PM...174...22...09...24...Sunset
11:48:00 PM...174...23...43...26...ISS maneuvers to relaxation attitude

9/24
12:04:23 AM...174...23...59...49...Soyuz deorbit burn starts (257.7 mph)
12:08:44 AM...175...00...04...10...Deorbit burn complete
12:09:00 AM...175...00...04...26...ISS maneuvers to Soyuz comm attitude
12:23:18 AM...175...00...18...44...Terminator rise
12:29:15 AM...175...00...24...41...Module separation
12:32:00 AM...175...00...27...26...ISS maneuvers to duty attitude
12:32:22 AM...175...00...27...48...Atmospheric entry (61.8 miles altitude)
12:33:57 AM...175...00...29...23...Entry guidance begins (50 miles altitude)
12:38:49 AM...175...00...34...15...Maximum G-load (21.4 miles altitude)
12:40:44 AM...175...00...36...10...Open parachute command (6.7 miles altitude)
12:55:44 AM...175...00...51...10...Landing
01:10:00 AM...175...01...05...26...Russian to US attitude control handover
09:11:00 AM...175...09...06...26...Sunset at landing site