Nikolai Budarin and his US crewmates Kenneth Bowersox and Donald Pettit, who had blasted off from the International Space Station on the Soyuz TMA-1 earlier Sunday, were to have been met after landing at around 6:00 am Moscow time (0200 GMT).

However, with the capsule landing some 440 kilometres (275 miles) away from the preset destination, rescue teams could not even locate the spacecraft and its crew for more than two hours, officials told AFP in the Kazakh capital.

Three helicopters carrying emergency and medical personnel finally reached the spot in the remote Kazakh steppe at 10:25 Moscow time (0625 GMT), where the three crew members were waiting outside their capsule.

Russian space officials indicated that the Soyuz, a new model of the more than three-decade old Russian rocket prototype, had to land using an uncontrolled ballistic trajectory rather than the usual manual or automatic function.

"There's no sense in overdramatizing the situation," the head of the Russian space agency Rosiavakosmos, Yuri Koptev, was quoted as saying by ITAR-TASS. "The main thing in our work is a happy ending, so that the crew after landing strolled around the craft and picked tulips."

But he conceded that there had only been two previous instances when Russian spacecraft had made ballistic landings, once involving a piloted craft and another with an unmanned rocket.

"That is why we were all worried," conceded Yury Semyonov, head of the Energiya space construction firm.

"But we definitely will find out the cause. It could be the crew's actions, the conditions at the start of the re-entry or the onboard systems," ITAR-TASS quoted him as saying.

Anxiety had been high ahead of the first landing on Earth since the February 1 Columbia disaster, when the US shuttle spacecraft broke up into bits during re-entry to the Earth's atmosphere, killing all seven crew members.

Bowersox and Pettit were also the first US astronauts to come back from space in a Russian Soyuz. They were travelling in a new TMA model which was making its first re-entry after its maiden launch last October.

NASA suspended all shuttle missions, including those to the ISS, in the wake of the tragedy, and Russian spacecraft currently provide the only transportation to the space station.

NASA officials waiting to welcome the ISS crew back to Earth in Astana voiced relief.

"Nobody panicked, nobody got hurt, the first landing of the TMA vehicle was a success. They will look into why it was this far short," Jim Newman, director of NASA's human spaceflight programme, told AFP.

A rescue airplane finally obtained visual contact with the capsule at 8:21 Moscow time (0421 GMT), giving the search teams the precise location of the crew.

Meanwhile, the astronauts had managed to open the hatch and get out of the vessel an hour and a half after the landing, officials said.

Unlike US shuttles, Russian Soyuz craft can be used only once in space.

Protected by a heat shield, the crew capsule plunges through the Earth's atmosphere, while the rocket burns up, and then hits the ground, its impact softened by parachutes and six small braking-rockets that fire two seconds before.

After a brief medical check-up, a helicopter airlifted the three crew members to Astana, from where they were to fly to the Star City astronaut centre outside Moscow.

Budarin, Bowersox and Pettit were all "feeling fine," officials at Russian mission control outside Moscow told AFP.

This was despite a very "rough" landing, in which the astronauts were likely to have briefly experienced up to nine times the force of Earth's gravity, according to the top ballistics expert at mission control, Nikolai Ivanov, quoted by ITAR-TASS.

"We always try for a controlled landing as it is the most comfortable for the crew, but a ballistic landing of the Soyuz also works and does not harm the astronauts' health," insisted Semyonov from Energiya.

The European Space Agency's representative in Russia, Alain Fournier-Sicre, told AFP that the failure to effect a manual or automatic landing meant that the spacecraft could not be directed to a precise location as it hurtled down to Earth.

"It means the control system didn't work," the ESA official said.

Bowersox, Pettit and Budarin had been aboard the ISS since December. They were originally to have left in March, but their return to Earth was delayed because of the Columbia disaster.

SPACE.WIRE