After orbiting Earth for 172 days, three members the International Space Station’s (ISS) Expedition 48 crew undocked their Soyuz TMA-20M spacecraft from the outpost and barreled through the atmosphere a couple hours later to land on the Steppe of Kazakhstan.
The official landing time was 09:13 EDT Sept. 6 (01:13 GMT Sept. 7) southeast of the town of Dzhezkazgan, Kazakhstan. Russian search and recovery teams circling the area in helicopters then landed near the capsule to help NASA astronaut Jeff Williams, and Russian cosmonauts Oleg Skripochka and Aleksey Ovchinin out of the Soyuz after their nearly six-month stay in at the orbiting laboratory.
Change of command
Preparations for Tuesday’s return to Earth began a day prior to landing with a change-of-command ceremony. This handover has been a tradition since the very beginning of the ISS program. Expedition 48 commander Williams handed over the reigns of the station to Russian cosmonaut Anatoli Ivanishin. He will be commander for the duration of Expedition 49. The later officially began the moment the Soyuz TMA-20M undocked.
“It’s more than a change of command, It’s a crew change,” Williams said. “Four times a year, crews change out half the crew at a time. It’s a significant event. It’s a bittersweet time.”
Williams went on to say he and his Soyuz crew mates are ready to go home and be with their families. He said they’ve enjoyed a great stay aboard the outpost over the last five-and-a-half months.
“But it’s the rhythm of life hear at the station,” Williams said.
Remaining on board the station are Ivanishin, Japanese astronaut Takuya Onishi and NASA astronaut Kate Rubins. They arrived to the outpost in Soyuz MS-01 back in July 2016.
“You will enjoy the time now with just three of you onboard,” Williams said. “It will be a little more quiet – not so many people you’re going to have to talk with. It’ll give you time to get settled in to make [station] a bit more of your own.”
The three remaining aboard ISS will be joined about 17 days later, Sept. 25, by Russian cosmonauts Sergey Ryzhikov and Andrei Borisenko and NASA astronaut Robert Kimbrough when they launch to the ISS aboard the Soyuz MS-02 spacecraft.
Williams reflects on his time in space.
Williams said while very one of the long-duration crews he’s been a part of – three, including this one – this particular crew, he believes, has a special chemistry about it.
“I think we’ve surpassed what you would expect from a crew in terms of how we work together in terms of how we trust each other, in terms of how we know each other, in terms of our friendships, knowing our families and caring about each other,” Williams said.
When reminiscing about the ISS, Williams said the station program is much bigger than just the astronauts.
“The International Space Station now spans, it just occurred to me last week, generations,” Williams said. “We’re in the second generation of crew and flight controllers and engineers and all of the disciplines to make this work.”
Leaving the outpost
The closure of the hatch between Soyuz TMA-20M and the Poisk module it was docked to occurred at 2:42 p.m. EDT (18:42 GMT).
After conducting a number of leak checks, the depressurization of the space between Poisk’s outer hatch and the Soyuz occurred. Then at 5:51 p.m. EDT (09:00 GMT), while the ISS was traveling over eastern Mongolia, the Soyuz undocked.
Springs pushed the spacecraft away initially. A few minutes later, the first of two separation burns occurred – lasting about 8 seconds. A couple of minutes after that, a second burn – lasting some 30 seconds – pushed the spacecraft outside the Keep-Out Sphere – an area of about 656 feet (200 meters) around the outpost.
“I’ve got a great view of station out of the right window here,” Williams radioed to the space station a couple of hours after undocking. “It looks like its several kilometers away, but the station’s looking beautiful.”
Rubins, back on ISS, responded in kind saying, “We watched you from Node 2 zenith and it was pretty amazing.”
“Well, godspeed on the rest of your flight,” Williams said. “I look forward to seeing you back on the ground.”
Soyuz TMA-20M reentry
At 8:21 p.m. EDT (00:21 GMT on Sept 7), when the spacecraft was some 7.5 miles (12 kilometers) away from the ISS, the vehicle performed a de-orbit burn lasting about 4 minutes 41 seconds to slow the spacecraft by 420 feet (128 meters) – just enough to dip into the atmosphere.
Just before entry interface, at 8:48 p.m. EDT (00:48 GMT Sept. 7), the three components of the Soyuz – the Orbital Module, Descent Module and Propulsion Module – detached in an event called “tri-module separation.”
The only piece that survives re-entry is the Descent Module, of which the crew resides in, as it has a heat shield.
Peak heating on the spacecraft occurred around just before 9 p.m. EDT (01:00 GMT Sept. 7). During the deceleration, the crew experienced around 4.14 times the force of Earth’s gravity.
At 9 p.m. EDT (01:00 GMT Sept. 7), a series of parachutes began deploying to slow the Soyuz down, ultimately to a speed of about 21 feet (6.5 meters) per second – down from the 4.73 miles (7.62 kilometers) per second at entry interface.
The descent under the main parachute took only about 10 minutes. During that time, the heat shield was jettisoned to reveal the Soft Landing engines. Next the cabin pressure was equalized to atmospheric pressure. Finally, the crew seats, called Kazbek, were moved slightly upward relative to the horizon in order help the crew absorb the shock of the landing.
About 1 second before touchdown, the Soft Landing engines ignited in a brief burst to cushion the final 3 feet (about 1 meter) of the crew’s return to Earth.
A textbook landing
The spacecraft landed on its side 24 minutes after sunrise. As such, there was still a surface haze from the moisture in the air. The temperature was about 66 degrees Fahrenheit (19 degrees Celsius). Winds were out of the east at about 6 knots. However, to prevent the capsule from being dragged across the steppe, the lines were automatically cut, as planned.
Once recovery crews arrived on site, they began to extract the crew. First was out was Ovchinin, as he was the Soyuz commander and in the center seat. He was followed shortly after by Williams, then Skripochka.
One by one, each were carried to nearby lawn-chair-like couches for initial health checks as well a drink of water. Ovchinin, as a joke, requested a watermelon – a request the ground team fulfilled.
This landing completes Ovchinin’s first spaceflight and Skripochka’s second long-duration flight.
Williams is on his fourth spaceflight. He has accumulated 534 days in space since his first mission aboard Space Shuttle Atlantis in May of 2000, making him the most-flown U.S. astronaut in history.
Additionally, this completes the final flight of the TMA-M series of the Soyuz. The MS variant has replaced it and is the final planned upgrade for the Soviet-era spacecraft.
About 30 minutes after landing, the crew was transported to a nearby orange inflatable medical tent where some field tests were conducted. After about an hour-and-a-half, they boarded a helicopter for a two-hour flight to Karaganda, Kazakhstan.
Once there, a small ceremony will be performed before Williams boards a NASA plane for a flight back to Houston. Ovchinin and Skripochka will fly back to Star City, Russia.
Space Flight Insider