By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - A Russian spaceship carrying two Russian cosmonauts and a U.S. astronaut made a belated arrival at the International Space Station on Thursday, returning the orbital outpost to full staff.
Russian cosmonauts Alexander Skvortsov and Oleg Artemyev and NASA astronaut Steven Swanson blasted off aboard a Russian Soyuz rocket two days ago from the Baikonur Cosmodrome in Kazakhstan.
They had expected to reach the station, a $100 billion research complex that flies about 250 miles above Earth, six hours later.
But about two hours after launch, the crew's Soyuz capsule failed to fire its maneuvering engines as planned, forcing a delay to the next station docking opportunity on Thursday.
The cause of the skipped rocket firing remains under investigation, said NASA mission commentator Rob Navias.
Preliminary analysis shows the spaceship was 1 degree out of alignment from its predicted orientation, triggering the Soyuz computers to automatically abort the engine burn, Navias said during a NASA Television broadcast of the docking.
Since Tuesday's mishap, the Soyuz successfully conducted the necessary engine firings to reach the station.
"Better late than never," said Navias as the Soyuz made its final approach to the outpost.
The crew's prolonged journey ended at 7:53 p.m. EDT as the Soyuz slipped into a berthing port on the station's Poisk module.
The arrival of Skvortsov, Artemyev and Swanson returns the station to a full six-member crew. The orbital outpost, a project of 15 nations, has been short-staffed since two other cosmonauts and a NASA astronaut returned to Earth on March 11.
The 15-nation space station partnership, overseen by the United States and Russia, so far has been immunized from the political and economic fallout following Russia's invasion of Ukraine's Crimean peninsula.
Since retiring its fleet of space shuttles in 2011, the United States is dependent on Russia to fly its astronauts to the station, a service that costs NASA more than $63 million per person.
NASA Administrator Charles Bolden, testifying before Congress on Thursday, said it is unlikely Russia will cutoff U.S. access to the station as payback for U.S. sanctions stemming from Russia's takeover of Crimea.
"Russia is dependent upon the United States to operate the station when it comes to power, when it comes to everyday operation," Bolden told members of the Space Subcommittee of the House Science, Space and Technology Committee.
"Based on my conversations with my Russian counterparts, they are equally worried about terminating activity on the ISS," Bolden said.
(Editing by Lisa Shumaker)