Ten seconds shy of midnight EDT on Saturday, 29 October, three spacefarers from three sovereign nations will return to Earth after almost four months aboard the International Space Station (ISS). Expedition 49 Commander Anatoli Ivanishin of Russia, together with NASA’s Kate Rubins and Japan Aerospace Exploration Agency (JAXA) astronaut Takuya Onishi, will have spent a little over 115 days in the microgravity environment, during which time they deftly supported hundreds of research experiments, oversaw the capture and berthing of two commercial visiting vehicles at the U.S. Orbital Segment (USOS), and supported a pair of long-overdue and critical EVAs. Tomorrow (Friday), Ivanishin will relinquish command of the space station to NASA astronaut Shane Kimbrough, who will lead Expedition 50 through late February 2017.
Ivanishin, Rubins, and Onishi were launched from Site 1/5—the famed “Gagarin’s Start”—at the Baikonur Cosmodrome in Kazakhstan at 7:36 a.m. local time on 7 July (9:36 p.m. EDT on 6 July), flying into orbit on the maiden voyage of Russia’s upgraded Soyuz-MS spacecraft. Equipped with higher-efficiency solar arrays, better propulsion system redundancy, the new “Kurs-NA” (“Course”) rendezvous hardware, a lighter flight computer, and improved telemetry, control, and autonomous navigation capabilities, Soyuz MS-01 followed a longer-than-standard profile to reach the ISS. Instead of the six-hour, four-orbit rendezvous regime adopted by most Soyuz crews since March 2013, it was necessary to conduct a longer profile of two days and 34 orbits, in order to thoroughly test the new spacecraft’s systems. Specifically, this included Soyuz MS-01’s ability to communicate via Russia’s Luch-5 tracking and data-relay satellite network for up to 70 percent of each orbit.
At length, Ivanishin completed a smooth docking at the space station’s Earth-facing (or “nadir”) Rassvet module at 00:06 a.m. EDT on 9 July, approximately 50 hours after launch. They were welcomed aboard their new orbital home by Expedition 48 Commander Jeff Williams of NASA and his Russian crewmates Alexei Ovchinin and Oleg Skripochka, who had been aboard since March. However, there existed little time to adapt, for a few days after the arrival of Ivanishin, Rubins, and Onishi, SpaceX launched its Commercial Resupply Services (CRS)-9 Dragon cargo mission. In addition to a full load of science hardware, the Dragon carried Boeing’s International Docking Adapter (IDA)-2 to provide an interface for future Commercial Crew vehicles. This was installed onto Pressurized Mating Adapter (PMA)-3 at the forward end of the space station’s Harmony node during a five-hour-and-58-minute EVA by Williams and Rubins on 19 August.
Taking advantage of delays to Orbital ATK’s OA-5 Cygnus cargo mission, a “window” in the late August timeframe allowed NASA and its International Partners (IPs) to press ahead with a second EVA on 1 September. Williams and Rubins successfully retracted the Trailing Thermal Control Radiator (TTCR), which had been deployed back in 2012 to provide an interim cooling capability. Its retraction negates the risk of it suffering Micrometeoroid Orbital Debris (MMOD) damage and makes it available for possible future use. Returning inside after their two EVAs, Williams became the oldest U.S. spacewalker and Rubins now stands as the world’s sixth most experienced female spacewalker.
A few days later, on 6/7 September, Williams, Ovchinin, and Skripochka boarded their Soyuz TMA-20M spacecraft, undocked from the station, and touched down smoothly in Kazakhstan. Shortly before undocking, Williams handed command of the ISS over to Ivanishin and Expedition 49 officially got underway as soon as Soyuz TMA-20M undocked. This was expected to leave Ivanishin, Rubins, and Onishi as a reduced crew of three for a couple of weeks, before Soyuz MS-02 launched from Baikonur on 23/24 September, carrying Russian cosmonauts Sergei Ryzhikov and Andrei Borisenko, together with NASA astronaut Shane Kimbrough. However, a technical problem with the Soyuz MS-02 spacecraft forced a month-long delay, and Ryzhikov, Borisenko, and Kimbrough did not ultimately launch until 19 October. Following a 34-orbit rendezvous, they docked smoothly at the space-facing (or “zenith”) Poisk module on 21 October. And two days after that, Orbital ATK’s long-awaited OA-5 Cygnus cargo ship was successfully captured and berthed at the nadir port of the station’s Unity node.
Tomorrow (Friday), Ivanishin will ceremonially transfer command of the ISS from himself to Shane Kimbrough, thereby inaugurating Expedition 50, just a few days shy of the 16th anniversary since the first long-duration increment got underway on 2 November 2000. In marking 50 discrete expeditions, the ISS has greatly surpassed the 28 increments flown to the Mir space station between March 1986 and June 2000. Including Kimbrough’s increment, the ISS has seen 24 American and 23 Russian commanders, as well as one apiece from Europe, Canada, and Japan. Another European astronaut, Germany’s Alexander Gerst, will command the station in fall 2018.
Farewells between the six crew members will take place Friday, with hatch closure between Soyuz MS-01 and the Rassvet module expected to occur at 5:15 p.m. EDT. Ivanishin will assume the center commander’s seat for the return to Earth, flanked by Onishi in the left-side “Flight Engineer-1” couch and Rubins in the right-side “Flight Engineer-2” couch. They will spent the next several hours donning and leak-checking their Sokol (“Falcon”) launch and entry suits and readying the spacecraft for undocking. At 8:36 p.m. EDT, Ivanishin will command the hooks between Rassvet and the Soyuz to open, allowing springs to push them apart. Physical separation of the two space vehicles is scheduled about 90 seconds later, officially ending Expedition 49 and beginning Expedition 50.
Soyuz MS-01 will initially move away at a slowpoke pace of 0.4 feet (0.12 meters) per second, before Ivanishin executes an eight-second engine “burn” at 8:40 p.m. EDT. This will increase the departure rate to 1.74 feet (0.53 meters) per second, by which time the spacecraft will have reached approximately 50-65 feet (15-20 meters) from the orbital outpost. Moving further out, Soyuz MS-01 will fire its engines for 21 seconds at 8:46 p.m. EDT, further increasing the rate of departure to 5.3 feet (1.63 meters) per second.
Sunrise over the desolate Kazakh steppe will occur at 8:04 a.m. local time Saturday (10:04 p.m. EDT Friday), with an area about 87 miles (140 km) northwest of the remote town of Dzhezkazgan being targeted as the primary landing site. About an hour before touchdown, Russian Mi-8 recovery and rescue helicopters will take to the air from Dzhezkazgan. By this point, around 2.5 hours will have passed since Ivanishin, Rubins, and Onishi undocked from the space station. At 11:06:36 p.m. EDT Friday, Ivanishin will execute the “deorbit burn,” committing Soyuz MS-01 to a perilous and fiery descent back through Earth’s atmosphere. By this stage, the spacecraft will occupy an orbit of 267 miles (429.8 km). The burn will run for four minutes and 38 seconds and will dramatically slow the spacecraft by about 420 feet (128 meters) per second.
Shortly thereafter, the crew will be instructed to close their visors. Twenty-seven minutes after the deorbit burn, at 11:33 p.m. EDT, the spherical orbital module and cylindrical instrument module will be jettisoned, leaving the bell-shaped descent module alone against the furnace heat of re-entry. By this stage, Soyuz MS-01’s altitude will have dropped to 86.8 miles (139.8 km), with a little more than 25 minutes remaining before touchdown. At the landing site, it will be 9:33 a.m. on Saturday morning and the Mi-8 helicopters should be in position, flying an oval-shaped “racetrack” pattern, as they await the arrival of Ivanishin, Rubins, and Onishi. “Entry Interface”—the point at which the descent module begins to feel the brunt of thermal stress—will occur at 11:36:34 p.m. EDT, at an altitude of 327,756 feet, or 62 miles (100 km).
After passing through the worst of re-entry heating at about 11:42:55 p.m. EDT, Soyuz MS-01 will emerge from plasma at an altitude of 109,580 feet, or 20.7 miles (33.4 km). Its twin pilot parachutes will be deployed at 6.6 miles (10.7 km), followed by the 258-square-foot (24-square-meter) drogue and, finally, the 10,764-square-foot (1,000-square-meter) main canopy. Recovery forces will confirm the successful parachute deployments and will establish voice communications with the crew, as Soyuz MS-01 heads toward the Central Asian steppe. The main canopy will slow the spacecraft’s descent rate to 23.6 feet (7.2 meters) per second and its harnesses will first orient the Soyuz at a 30-degree angle to expel heat, before shifting it to a straight-vertical final descent.
Although slowed significantly, this is still not enough for a safe landing. Two seconds and just 2.6 feet (0.8 meters) before hitting the ground, six solid-fueled rockets in the descent module’s base will ignite to reduce the descent rate to just 5 feet (1.5 meters) per second. Touchdown of Soyuz MS-01 at co-ordinates 47.18 degrees North latitude and 69.35 degrees East longitude is scheduled for 11:59:50 p.m. EDT Friday (9:59:50 a.m. local time Saturday), about 3.5 hours after departing the ISS. Ivanishin, Rubins, and Onishi will be home after a remarkable expedition which will have lasted 115 days, 2 hours, and 22 minutes.
When one counts a handful of shorter increments in the 2008-2009 timeframe—by European astronaut Leopold Eyharts and NASA flyers Garrett Reisman, Tim Kopra, and Nicole Stott—the flight of Ivanishin, Rubins, and Onishi represents the fifth-shortest expedition in ISS Program history. However, since Eyharts, Reisman, Kopra, and Stott flew for only part of a longer expedition, Ivanishin’s crew actually sits in first place for the shortest single increment ever undertaken aboard the ISS. Initially scheduled to launch on 20/21 May 2016, they were delayed for operational and technical reasons into the late June and eventually early July. At the same time, their return date at the end of October remained unchanged, thus shortening their original 160-day mission by around 30 percent.
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