ISS Expedition 28 will come to an end just after midnight tomorrow when the Soyuz TMA-21 spacecraft brings ISS Crewmembers Andrei Borisenko, Alexander Samokutyaev and Ron Garan back home to Earth.
Aboard the ISS, traditional change of command procedures have already taken place. Russian Crewmembers formally handed over the Russian Segment. The Commander-to-Commander Handover between Andrei Borisenko, Expedition 28 CDR, and Mike Fossum, Increment 29 CDR, was performed later. Handover procedures involve different things such as lessons leanred from the past increment, open work and other items of note. The televised Change of Command Ceremony with all crewmembers was on Wednesday at 5:40pm EDT. Some words of appreciation were exchanged between the two Commanders along with congratulations on a very successful Increment 28 that saw the final Space Shuttle Missions. The entire crew has adjusted their sleep cycle for the planned undocking time.
Change of Command Ceremony
Undocking&Landing was delayed by a week after the August 24 Soyuz-U Failure causing other Soyuz Launches to be grounded.
Undocking is set for 8:38pm EDT on Thursday. Three hours before Undock, the crew will get ready for a final Good Bye and to close hatches between the Station and the departing capsule. Reconfigurations and activations of the vehicle’s systems will be performed before the undocking sequence is being initiated. When hooks and latches are open between the Soyuz and the Docking Port, small thruster impulses will slowly carry the spacecraft away from the ISS. At a distance of 66 feet – about 6 minutes after intial separation – the first separation burn is being conducted. This is a 15-second engine firing that will increase the Soyuz’ opening rate. The vahicle will continue to fly away from the Station and preparations for the deorbit burn will get underway. About 2.5 hours after undocking, at a distance of 12 miles to the ISS and 54 minutes prior to landing, the deorbit burn begins. This engine burn will last for approximately 4 minutes and 20 seconds and slow the vehicle down just enough to drop out of orbit. At an altitude of 87 miles, about 26 minutes before landing, the descent module separates from the orbital module and instrumentation module which will burn up a short time later. Three minutes later, the Soyuz will hit the atmosphere at 400,000 feet. Commands are sent to open parachutes 15 minutes before the Soyuz hits the ground. Two Pilot Parachutes are deployed. One of those extracts the Drogue Chute which slows the vehicle’s descent rate from 755fps to 262fps. Then, the main parachute is released to slow the descent to a speed of 24 feet per second. Initially, the chute allows a 30° angle of descent to expel excess heat before shifting to a vertical descent level. When instruments indicate that the Soyuz is about to hit the ground (at 2.6 feet in altitude) six Soft Landing Engines fire to slow the descent rate to 5 feet der second. Those are solid rocket motors that are automatically ignited. 3 hours and 23 minutes after undocking, the Spacecraft is back on Earth. The Soyuz TMA-21 will land 22 seconds after midnight EDT to end a six-month mission for its three crewmembers after launching on April 4, 2011. The Syouz TMA-21 will land 149 kilometers southeast of the town of Dzhezkazgan in Kazakhstan. Recovery teams will be placed at the landing site and will reach the landed vehicle within minutes to open the hatch and help the crew exit their Soyuz. Teams will also be present at the Ballistic Landing Point and between the two possible landing sites in case an off-nominal descent occurs.
After coming out of the vehicle, the crew will be placed in reclining chairs for initial medical checks and re-adaption to Earth’s gravity. Two hours after landing, the three Cosmonauts/Astronauts will depart the landing site. Traditional welcome ceremonies are scheduled later on Friday. Ron Garan will be flown back to Houston. His first post-flight interview is currently planned for September 22.
A Soyuz Spacecraft after Undocking
Landing Engine Ignition and Touchdown
Full Undocking and Landing Timeline
|EDT||Undock +/-||Landing +/-||Event|
|02:00:00pm||-06:38:00||-10:00:22||Soyuz Loading Complete|
|02:40:00pm||-05:58:00||-09:20:22||Communication Reconfiguration for Undock|
|07:45:00pm||-0:53:00||-4:15:22||ISS hands to RS Control|
|07:52:00pm||-00:44:00||-4:08:22||ISS Maneuver to Undocking Attitude|
|08:33:47pm||-00:04:13||-3:26:35||Russian Ground Station Acquisition of Signal|
|08:34:00pm||-00:04:00||-3:26:22||ISS Control to Free Drift Mode|
|08:35:00pm||-00:03:00||-3:25:22||Command Undocking Sequence|
|08:44:00pm||+00:06:00||-3:16:22||Range: 66 feet; Sep. Burn #1|
|08:52:01pm||+00:14:01||-3:08:21||Russian Ground Station Loss of Signal|
|09:00:00pm||+00:21:00||-3:00:22||Sunrise at Landing Site (Kazakhstan)|
|09:30:00pm||+00:52:00||-2:30:22||ISS Handover to US Control|
|10:02:46pm||+01:24:46||-1:57:36||Russian GS AOS|
|10:27:15pm||+01:49:15||-1:33:07||Russian GS LOS|
|11:05:27pm||+02:27:27||-0:54:55||Deorbit Burn (4:20 Duration)|
|11:33:23pm||+02:55:23||-0:26:59||Module Separation; Altitude: 87 Miles|
|11:37:00pm||+02:59:00||-0:23:22||Entry Interface @ 400,000feet|
|11:38:30pm||+03:00:30||-0:21:52||Entry Guidance enabled|
|11:43:00pm||+03:05:00||-0:17:22||Max Stress on the Vehicle|
|11:45:20pm||+03:07:20||-0:15:02||Parachute Opening Command|
|12:00:20am||+03:22:20||-0:00:02||Soft Landing Engine Ignition|
|~02:00:22am||~+05:22:22||~+02:00:00||Crew departs Landing Site|