A U.S. astronaut and two Russian cosmonauts boarded the International Space Station early Sept. 26, restoring the orbiting science lab to six crewmembers and setting up a resumption of rendezvous activities with Orbital Sciences’ Cygnus resupply mission under NASA’s Commercial Orbital Transportation Systems (COTS) program.

Cygnus’ final approach and berthing could unfold Sept. 29, with robot arm capture by station astronauts at 7:15 a.m. EDT, pending an ISS Mission Management Team review on Sept. 27.

Russia’s Soyuz TMA-10M delivered veteran cosmonaut Oleg Kotov and first-time space travelers Sergey Ryazanskiy, a fellow cosmonaut, and U.S. astronaut Mike Hopkins to the ISS with an automated docking at the Russian segment Poisk docking port on Sept. 25 at 10:48 p.m. EDT. They were greeted by ISS Expedition 37 commander Fyodor Yurchkhin, NASA’s Karen Nyberg and the European Space Agency’s Luca Parmitano as they floated aboard on Sept. 26 at 12:34 a.m. EDT to begin a six-month stay.

The Soyuz crew transport lifted off from the Baikonur Cosmodrome in Kazakhstan on Sept. 25 at 4:58 p.m., setting up a third consecutive four-orbit, 6-hr. launch to docking flight for new ISS crewmembers rather than the traditional two-day transit.

The “express” timeline sets up a second attempt by Orbital and NASA’s Mission Control to orchestrate a rendezvous and ISS robot arm capture of the unpiloted Cygnus capsule no sooner than Sept. 29, according to Joel Montalbano, NASA’s deputy ISS program manager.

Shortly after the Soyuz docking, the Cygnus capsule’s four flight computers were rebooted and a software patch was transmitted to correct the GPS navigation mismatch that disrupted the original plan for a Sept. 22 rendezvous and robot arm capture by Parmitano and Nyberg. A one-day postponement was subsequently extended until the Soyuz flight was complete.

The ISS mission management team is scheduled to meet Sept. 27 to review preparations for the effort.

Orbital launched Cygnus on Sept. 18 with a noncritical 1,543-lb. cargo of crew provisions to complete the final demonstration phase of the Dulles, Va.-based company’s $288 million NASA COTS agreement. A successful rendezvous and berthing qualifies Orbital to launch ISS supplies on a commercial basis under a $1.9 billion, eight-mission NASA contract.

As the Soyuz flight unfolded, Cygnus occupied a parking orbit 2.4 mi. above and 930 mi. behind the 260-mi.-high ISS.

The TMA-10M crew replaces ISS crewmembers Chris Cassidy, Pavel Vinogradov and Alexander Misurkin, who descended to Earth on Sept. 10 after 5 1/2 months in orbit.

Kotov, a physician and colonel in the Russian air force, logged 359 days in orbit during ISS missions in 2007 and 2010. Ryazanskiy, a biochemist, joined Russia’s cosmonaut corps in 2003. Hopkins, a U.S. Air Force colonel and flight test engineer, is the first of NASA’s 2009 class of astronauts to launch.

Their tour of duty is expected to include three Russian spacewalks for the installation of science equipment and external maintenance, and visits by a Cygnus cargo craft in December and SpaceX Dragon and Russian Progress freighters early next year.