"Docking confirmed, new residents have arrived at the international space station," announced NASA spokesman Rob Navias.
With Expedition 9 commander Gennady Padalka at the controls, the Soyuz TMA-4 spacecraft docked with an Earth-facing port in the station's Zarya module at 1:01 a.m. EST as the two vehicles sailed across central Asia, reports CBS News Space Consultant Bill Harwood.
Padalka and NASA astronaut Michael Fincke will replace Expedition 8 commander Michael Foale and cosmonaut Alexander Kaleri, who plan to return to Earth a week from Thursday to close out a six-month voyage.
"I see smiles on both of your faces," NASA Deputy Administrator Frederick said to both crews upon arrival. "I'm sure Expedition 9's smile is because they're coming home soon, and 10, because they've just arrived."
Foale and Kaleri will be joined on the return flight by newly-arrived European Space Agency astronaut Andre Kuipers from the Netherlands, who blasted off with Padalka and Fincke late Sunday for nine days of on-board research.
"So far it was excellent, it was fantastic," said Kuipers. "We are looking forward to starting the program."
Padalka and Fincke, who were initially trained to fly on a U.S. shuttle, are to conduct two spacewalks during their 183-day stint on the space station.
"I want to thank the Russian Space Agency for again providing an excellent launch, an excellent ride and an excellent docking," Gregory said at a post-docking news conference. "As we continue this great friendship and journey together, we appreciate everything that has been done."
He was referring, presumably, to Russia's critical support of station operations while NASA'S shuttle remains grounded in the wake of the Columbia disaster.
The Russians are struggling financially and Gregory was asked about NASA's recent decision to turn down a Russian suggestion to increase the length of the next crew's stay aboard the station from six months to a full year. That would free up seats on regular Soyuz rotation flights for space tourists or other paying customers.
"The extension for Expedition 10, we believe, was a bit premature for us," Gregory said. "We would like to delay any further decisions on this until we return (the shuttle) to flight, which will be scheduled for next March, so we can assure that all the (station's) operating systems ... are operating and we can get back up to full (three-person) contingent. October was just too soon for us, but we are considering that one-year extension for perhaps a later flight."
Every paying passenger, whether it be a European astronaut or a space tourist, generates some $20 million for the financially-challenged Russian space program, reports CBS News Correspondent Peter King.
Yuri Semenov, president and chief designer for the Russian rocket company Energia, countered by saying "we have a very strong position that the next crew needs to be flying for a longer duration flight on board the station."
"So we need to keep talking to our American colleagues about that," he said. "Because the shuttle launch keeps moving away, keeps shifting further and further, and we have already posed that question to our American colleagues. We need to make sure the station is operational in the meantime.
"So we need to understand what the needs are for our European colleagues as well as station needs," he said. "We just heard (NASA is) not ready. We think that we are ready, hardware wise, and so that's our position. Based on that position, we are going to prepare our vehicles and our hardware."
CBS News Space Consultant William Harwood has covered America's space program full time for nearly 20 years, focusing on space shuttle operations, planetary exploration and astronomy. Based at the Kennedy Space Center in Florida, Harwood provides up-to-the-minute space reports for CBS News and regularly contributes to Spaceflight Now and The Washington Post.