The seven-day space sojourn of a U.S. millionaire scientist came to a close as he and a two-man Russian-American crew undocked early Tuesday from the international space station and began speeding back to Earth.

The ride back in the Russian Soyuz capsule (search) is likely to be an exciting conclusion to Gregory Olsen's (search) space station visit — the third trip by a private citizen. The Soyuz is to make a beeline home, covering the approximately 250 miles from the station to Earth in just 31/2 hours.

The craft is to land on the broad, empty steppes of Kazakhstan (search), where Russia's manned-space facilities are based, around dawn on Tuesday.

Olsen, the American astronaut William McArthur (search) and the Russian Valery Tokarev blasted off from the Baikonur launch facility in Kazakhstan on Oct. 1 and docked with the space station two days later. McArthur and Tokarev will stay aboard the station for six months, while Olsen returns with John Phillips and Sergei Krikalev, who had been there since April.

The trio entered the Soyuz and closed the hatch Monday night to prepare for the return trip, said Valery Lyndin, spokesman for Russian Mission Control. After landing, they are to spend two hours undergoing medical checks, then be shuttled by helicopter to a Kazakh staging point and ultimately back to Moscow for further examinations.

McArthur and Tokarev are expected to conduct two spacewalks during their time aboard the station, as well as an array of scientific experiments, medical tests and maintenance. The next cargo shipment they can expect will be a Russian Progress ship, scheduled to reach the station in December.

Olsen, who spent two years in training and paid $20 million for his trip, has conducted experiments during his visit, including one to determine how microbes that have built up on the space station are affected by flight, particularly if their rate of mutation has been affected.

The Soyuz spacecraft and Russia's unmanned Progress cargo ships have been the space station's lifeline since the U.S. space shuttle Columbia disaster in 2003. The shuttle program was suspended for more than two years; the shuttle Discovery flew to the station in July, but problems with its insulation raised doubts about the timing of the next shuttle launch.

Despite chronic funding problems, Russia's space program has maintained a reputation for reliability in recent years, although its image was tarnished over the past week with a pair of failed unmanned missions.

Russian media reported Monday that the botched launch of a costly, state-of-the-art European satellite and Russia's failure to recover an experimental space vehicle after its blastoff have jeopardized its hopes of earning foreign cash.

The loss of the CryoSat satellite due to the failure of a Russian Rokot booster dealt a major blow to the European Space Agency, which had hoped to conduct a three-year mapping of polar sea ice and provide more reliable data for the study of global warming.

Russia's Khrunichev company, which built the booster, apologized for the loss of the estimated $210 million CryoSat.

"Moscow's space ambitions have sunk in the Arctic Ocean," the daily Nezavisimaya Gazeta commented.