Almost two days later than planned, Soyuz TMA-12M and its three-man crew of Russian cosmonauts Aleksandr Skvortsov and Oleg Artemyev and U.S. astronaut Steve Swanson have arrived safely at the International Space Station (ISS), their orbital home for the next six months. Launched from Baikonur Cosmodrome in Kazakhstan at 3:17 a.m. local time Wednesday (5:17 p.m. EDT Tuesday), the crew was originally supposed to follow a four-orbit “fast rendezvous” regime to produce a docking at the station about six hours later. However, although two maneuvering “burns” were successfully completed, problems arose shortly before the third burn, probably due to a software error, and this prompted Russian flight controllers to revert to a standard, two-day, 34-orbit rendezvous. Under this new profile, Soyuz TMA-12M docked perfectly at the space-facing (or “zenith”) port of the station’s Poisk module at 7:53 p.m. EDT Thursday. At the time of docking, the spacecraft were flying 252 miles (405 km) above northern Brazil.
Same-day rendezvous and docking are nothing new. In September 1966, Gemini XI astronauts Charles “Pete” Conrad and Dick Gordon accomplished a rendezvous and docking with an Agena target vehicle just 85 minutes and a single orbit after their launch. Several years later, during the Skylab era, crews typically followed an expedited rendezvous profile lasting just eight or nine hours to reach their home in space. Soviet and Russian crews aboard the Salyut, Mir, and ISS stations typically followed longer, two-day regimes, which proved more economical in terms of propellant expenditure and the demands of orbital mechanics. Coupled to these factors was a human element. Conditions inside Russia’s Soyuz spacecraft—whose pressurized segment includes the bell-shaped descent module and spherical orbital module—are particularly cramped, highly stressful, and tend to exacerbate nausea and motion sickness. It was therefore decided that, although hugely complex, a process would be developed to get crews to the space station more quickly.
First trialed by an unmanned Progress resupply craft in August 2012, the six-hour, four-orbit rendezvous and docking plan was successfully executed by the Soyuz TMA-08M crew in March 2013. Since then, three other crews have also accomplished docking within six hours of liftoff, although it was always recognized that if problems developed during one of the critical maneuvers flight controllers would revert to a standard, two-day rendezvous profile.
In the immediate aftermath of their insertion into an orbit of 124 x 163 miles (199 x 262 km), inclined 51.6 degrees to the equator, Skvortsov, Artemyev, and Swanson oversaw the successful deployment of the Soyuz TMA-12M spacecraft’s twin solar arrays and communications and navigational appendages. Four maneuvering burns were necessary to raise their orbit to reach the ISS operational altitude of 255 x 258 miles (411 x 416 km). “To start raising its orbit right away,” noted Spaceflight101, “Soyuz launched with two burns programmed into the flight computer for the first orbit around Earth.” The first, 84-second burn (DV-1) took place 45 minutes into the mission, followed by the second, 64-second burn (DV-2), which occurred 90 minutes after launch. Both were completed without incident, according to Russian flight controllers. However, shortly before the second pair of burns were scheduled to begin, Soyuz TMA-12M apparently displayed a failure message which precluded its software from commanding the third, 25-second firing. Both it and the fourth burn were scrubbed.
“Missing a burn in the four-orbit rendezvous automatically leads to an abort,” explained Spaceflight101, “because the compressed timeline has no room for a correction maneuver. When inaugurating the four-orbit mission profile, trajectory planners included an exit option after DV-2 that allows the Soyuz to revert to the original flight profile that took about two days from launch to docking.”
It subsequently became clear that an attitude control system malfunction occurred just prior to the third (DV-3) burn. Since the spacecraft was not correctly oriented to execute the firing, the burn was called off and the three crewmen set to work removing their Sokol (“Falcon”) launch and entry suits and opening up the hatch to Soyuz TMA-12M’s spherical orbital module. NASASpaceflight.com also pointed out that the improper orientation of the spacecraft “was caused, in part, by an over-performance of the Soyuz-FG [booster’s] ascent.” Suspicion has fallen upon a software problem, rather than a sensor or propulsion system failure, although Russian flight controllers stressed that they required more time to downlink the pertinent data in order to zero in on the root cause.
To support a revised, two-day, 34-orbit rendezvous profile, Skvortsov, Artemyev, and Swanson performed a pair of thruster firings on their fifth orbit—about seven hours into the mission—which raised their relative altitude “above” that of the ISS, in order that the space station would pass “below” them on Thursday, 27 March. Additional burns today positioned Soyuz TMA-12M “behind” the orbital outpost and the automated rendezvous protocol got underway. At a distance of about 1,300 feet (400 meters), Skvortsov began a flyaround of the ISS to line his craft up with the space-facing (or “zenith”) Poisk module. He paused at 590 feet (180 meters), for a pre-planned period of station-keeping, in order to allow flight controllers to perform systems checks and verify the alignment of the two vehicles, then proceeded toward a smooth docking at Poisk at 7:53 p.m. EDT.
As this article was being prepared, a lengthy series of pressurization and other checks were underway, preparatory to hatch opening between Soyuz TMA-12M and the ISS. This was scheduled to occur about two hours after docking, and Skvortsov, Artemyev, and Swanson will be greeted by the incumbent Expedition 39 crew of Koichi Wakata, Mikhail Tyurin, and Rick Mastracchio. This trio have been in orbit since early November 2013 and will remain aloft until mid-May. Two weeks ago, with the departure of Expedition 38, Wakata became the first Japanese to command the ISS.
With the arrival of Skvortsov, Artemyev, and Swanson, Expedition 39 increases to six members. However, there will be little time for the newcomers to adapt to their surroundings, for in the next few weeks SpaceX will launch the third dedicated Dragon cargo mission (SpX-3) under its $1.6 billion Commercial Resupply Services (CRS) contract with NASA. It is scheduled to be berthed, via the 57.7-foot (17.6-meter) Canadarm2 robotic arm, onto the Earth-facing (or “nadir”) port of the Harmony node. It will remain in place for about a month. On 7 April, Russia’s Progress M-22M cargo ship will depart the ISS and shortly be replaced by the fresh Progress M-23M. Later in April, the Progress M-21M cargo ship—which has been docked at the station since November 2013—will undock for two days of tests of its Kurs-NA (“Course”) rendezvous and navigation systems. After redocking on 25 April, Progress M-21M will remain at the ISS until mid-June.
Three major events will occur in May. The first is Orbital Sciences Corp.’s second dedicated Cygnus cargo mission (ORB-2), under its $1.9 billion CRS contract with NASA, originally planned for launch on the 6th. However, Eastern Range tracking problems have suspended the launches of both SpX-3 and United Launch Alliance’s (ULA) Atlas V with its NROL-67 classified payload. No new launch date for SpX-3 has been released. NASA presently lists it as “TBD” (To Be Determined), but since it will berth at the same port (Harmony nadir) as ORB-2, its month-long journey to the ISS must be completed before Cygnus can fly. This will undoubtedly create a domino-like effect on the queue of Visiting Vehicles in the early part of this summer.
The second event is the planned return to Earth of Soyuz TMA-11M crewmen Wakata, Tyurin, and Mastracchio on 14 May, completing a mission of 188 days. Shortly before their departure, Wakata will formally hand command of the ISS over to Steve Swanson, who will take the helm of the new Expedition 40. Two weeks later, on 28 May, Soyuz TMA-13M will launch with its crew of Russian cosmonaut Maksim Surayev, NASA astronaut Reid Wiseman, and Germany’s Alexander Gerst—the latter of whom is participating in the European Space Agency’s (ESA) “Blue Dot” mission—to bring Expedition 40 up to six-man strength.
The month of June is expected to feature the undocking and departure of both Progress M-21M and the ORB-2 Cygnus mission, with July highlighted by the expectation of two U.S. EVAs. According to NASASpaceflight.com, U.S. EVA-26 will involve Swanson and Wiseman and will take place on or around 10 July, with Wiseman and Gerst performing EVA-27 a week later on 17 July. Cosmonauts Skvortsov and Artemyev will perform Russian EVA-38 in August. Although Swanson is a veteran of four previous spacewalks—having racked up a cumulative 26 hours and 22 minutes in two excursions on each of his STS-117 and STS-119 shuttle missions, back in June 2007 and March 2009 respectively—Wiseman, Gerst, Skvortsov, and Artemyev have yet to savor the experience of EVA.
Russian cargo ships will perform a changeout in July, as Progress M-23M departs and Progress M-24M arrives a few days later, with ESA’s fifth and final Automated Transfer Vehicle (ATV)-5 also planned for launch on 25 July. Named in honor of the Belgian astronomer Georges Lemaître, ATV-5 will be boosted aloft by an Ariane 5 vehicle, whose “cryotechnic main stage” arrived at the Guiana Space Centre on Thursday, 20 March for pre-launch processing. August is expected to see SpaceX’s fourth Dragon mission (SpX-4) and Expedition 40 will conclude on 11 September with the return of Skvortsov, Artemyev, and Swanson aboard Soyuz TMA-12M, touching down in Kazakhstan, after a voyage lasting approximately 170 days. In leaving the ISS, Swanson will hand command of the space station over to Surayev, who will lead Expedition 41.