A Japanese astronaut, a veteran Russian cosmonaut and a NASA flight engineer boarded their Soyuz ferry craft and undocked from the International Space Station Tuesday, setting their sights on a fiery plunge back to Earth to close out a 188-day stay in space.
The international crew's return aboard a Russian spacecraft was the first such flight since Russia's annexation of Crimea, the imposition of U.S. and European sanctions and escalating Cold War rhetoric that stands in stark contrast to the close cooperation that has been the hallmark of the International Space Station program.
In the latest space-related tit for tat, Dmitry Rogozin, Russia's deputy prime minister for space and defense, told Russian news agencies future sales of RD-180 engines, which power the first stage of United Launch Alliance's Atlas 5 rocket, will not be permitted for launches of U.S. military payloads.
The Atlas 5 is routinely used for Pentagon missions and its reliance on Russian engines has come under fire in the wake of the Ukraine crisis. ULA competitor SpaceX has argued that payments for the RD-180 violate Obama Administration sanctions, but a temporary injunction was lifted last week based on assurances by the departments of Treasury, State and Justice that the sales were compliant.
In any case, ULA officials say the company has a two-year supply of RD-180s in hand and it's not yet known what impact Rogozin's statements might have down the road.
Both sides say the station program is not affected by sanctions or other diplomatic hurdles and the Russians continue to honor their lucrative contract with NASA to carry U.S. and partner astronauts to and from the space station aboard Soyuz spacecraft at more than $70 million a seat.
The Soyuz landing and another Soyuz launch later this month to carry three fresh crew members to the orbital complex highlight NASA's lack of an operational crew-carrying spacecraft of its own and the agency's dependence on the Russians for basic space transportation until at least 2017, when a U.S. ferry craft should be ready for service.
That assumes the program receives the necessary funding from Congress and the station program continues to operate smoothly, with the full cooperation of all the international partners. The station cannot be safely operated by either side without the other.
The station crew flies 260 miles above the complex geopolitical landscape and from their perspective, the Ukraine crisis has had no impact on day-to-day operations. Entry preparations have proceeded normally, the Soyuz TMA-11M spacecraft has been checked out and the stage is set for three members of the station's six-man crew to return to Earth.
With commander Mikhail Tyurin at the controls, flanked on the left by flight engineer Rick Mastracchio and on the right by outgoing Expedition 39 commander Koichi Wakata, the Soyuz TMA-11M spacecraft undocked from the Russian Rassvet module at 6:36 p.m. EDT (GMT-4) as the two spacecraft sailed 260 miles above Mongolia.
After moving a safe distance away, Tyurin planned to monitor an automated deorbit rocket firing, a four-minute 41-second "burn" designed to slow the spacecraft by about 286 mph, just enough to drop the far side of its orbit deep into the atmosphere.
A half-hour later, just before reaching the top of the discernible atmosphere at an altitude of about 62 miles, the three modules making up the Soyuz TMA-11M spacecraft were expected to separate, leaving the heat shield-equipped central crew cabin on its own for a northeasterly descent toward the landing site in Kazakhstan.
After plunging to an altitude of just under seven miles, the crew compartment's main parachute was expected to unfurl around 9:44 p.m. to slow the descent even more. If all goes well, the crew module will settle to a jarring rocket-assisted touchdown near the town of Dzhezkazgan around 9:58:34 p.m. (7:58 a.m. Wednesday local time).
"I was a flight engineer on the space shuttle, but I didn't have my own set of controls," Mastracchio said in a pre-launch interview. "Here in the Soyuz, I'm also the flight engineer but I'm actually going to be helping control the vehicle along with the commander.
"So I'm looking forward to having that front row seat, if you will, and actually helping operate the vehicle."
Learning how to operate a spacecraft is challenging under any circumstances. It was especially tough to do in a second language.
"It's very, very challenging," Mastracchio said. "Being an engineer, I have the skills to learn how to fly a vehicle and how to operate a vehicle, but the language skill was very challenging for me. It's not as easy as it sounds to fly a spacecraft while speaking a foreign language! Again, a big challenge, which made it very interesting to me."
As usual with Soyuz landings, Russian recovery forces were deployed near the landing site, ready to help the returning space fliers get out of the cramped spacecraft as they begin the process of re-adapting to Earth's gravity after six months in weightlessness.
In keeping with Russian traditions, Tyurin, Mastracchio and Wakata were expected to be carried from the capsule to nearby recliners where they could relax, enjoy their first fresh air in months and make satellite phone calls to friends and family.
Assuming an on-time landing, Tyurin will have logged 532 days in space during three space flights, moving him up to 11th on the list of most experienced space fliers. Wakata's total through two shuttle flights and a previous station stay will increase to 348 days while Mastracchio's numbers, including three shuttle flights, will climb to 228 days.
After initial medical checks, all three were expected to board Russian helicopters for a short flight to a staging base in Karaganda. From there, Mastracchio and Wakata planned to board a NASA jet for the long flight back to the Johnson Space Center in Houston while Tyurin heads home to Star City near Moscow.
During the course of their stay aboard the station, Tyurin, Mastracchio and Wakata delivered an Olympic torch to celebrate the 2014 Winter Games in Sochi and Mastracchio participated in three spacewalks, two to repair the station's cooling system and one to replace a balky computer.
The crew also carried out extensive troubleshooting to recover from a potentially catastrophic spacesuit water leak last summer and operated a full slate of scientific experiments.
Left behind in orbit were Expedition 40 commander Steven Swanson, Soyuz TMA-12M commander Alexander Skvortsov and flight engineer Oleg Artemyev. They will have the space station to themselves until May 28 when Soyuz TMA-13M commander Maxim Suraev, NASA flight engineer G. Reid Wiseman and European Space Agency astronaut Alexander Gerst blast off from the Baikonur Cosmodrome in Kazakhstan for a planned four-orbit flight to the lab.
The space station is generally healthy, but engineers are continuing to troubleshoot an electrical glitch last week that took down one of the eight electrical power channels driven by the lab's U.S. solar arrays.
Equipment on channel 3A, including the Alpha Magnetic Spectrometer and an experimental laser communications package, briefly lost power but flight controllers quickly switched affected systems to channel 3B without any major impact.
It is not yet clear what caused the remote bus isolator to "trip open" May 8, but a similar problem occurred in 2012 and engineers are reviewing telemetry to determine how to restore channel 3A to normal operation.
During a change-of-command ceremony Monday, Wakata, a shuttle veteran and the first Japanese to command the space station, thanked his crewmates for "an exciting time" in orbit.
"I had the honor of serving as commander, which was an incredible opportunity for me to extend my knowledge and experience in managing this complex outpost of humans in space," he said. "And I couldn't have done this job without the superb performance of my fellow crewmates."
Turning over command to Swanson, a former shuttle crewmate, Wakata offered his "congratulations and best wishes for a successful mission."
Swanson returned the praise, thanking Wakata, Tyurin and Mastracchio for sharing their experience.
"When we first got here, you guys were very kind to us, you gave us so much friendship, it meant so much to us," Swanson said. "And it makes it a little bit of a sad moment for me, because I've come to grow to like you guys very much. I would wish we could be up here for a long time, but I know you have to go.
"But again, thank you all for the experience you guys have given us, the knowledge you have given us. You have together a combined 11 spaceflights and over three years of time in space, which is just amazing, and that knowledge you have given us is fantastic. I really appreciate it."
Swanson then spoke to Wakata personally, saying "your leadership was fantastic."
"You set an example that will be very hard to match," Swanson said. "Your diligence, your endless energy, your desire to make the station as best as it possibly could be was just a pleasure to watch. I'm truly very proud to have been a part of your crew."