The space station crew captured this dramatic view of the approaching shuttle Discovery. Photo: NASA TV/Spaceflight Now

Space shuttle Discovery crossed the finish line of its two-day race to the international space station on Sunday, docking to the orbiting outpost about 250 miles above northwestern Australia.

"Capture!" pilot Rick Sturckow radioed as the two spacecraft came together at 2:41 p.m. EDT.

Two hours later the hatchway between Discovery and Alpha was opened, uniting the 10 astronauts and kicking off a busy week of joint activities.

The Expedition Two crew of Yuri Usachev, Susan Helms and Jim Voss welcomed the shuttle fliers to the station with a ceremony inside the Destiny laboratory.

"Hey, how you doing?" shuttle commander Scott Horowitz said to Usachev. "You ready for visitors?"

"Good to see you!" someone chimed.

"We made it. This is like old times!"

"Hello, commander, how you doing?" someone, possibly Culbertson, said. "You look great."

"All right. Let's go to station!"

"Come on over!" Helms called from the Destiny module.

Shuttle Discovery nears its link up with Alpha on Sunday. Photo: NASA TV/Spaceflight Now

The main objective of Discovery's mission is the exchange of resident crews living aboard the space station. On Monday, the Expedition Two astronauts will trade places with the three-man Expedition Three crew of Frank Culbertson, Vladimir Dezhurov and Mikhail Tyurin.

The Expedition Two crew will ride Discovery back to Earth next week after five months in orbit. Expedition Three will remain in space until December, conducting a variety of science experiments and three spacewalks outside the Russian segment of the station.

"Spirits are fantastic," station flight director Mark Ferring told reporters Sunday evening. "There's kind of a bittersweet feeling in the air for the Expedition Two guys, of course. They are greeting their replacements ... they're getting ready to go home to see their loved ones, but they're leaving the station that they've come to know and love. They've built a lot of it themselves and kind of made it home. I know that Frank and Vladimir Dezhurov and Mikhail Tyurin, who are coming to replace them as Expedition Three, will be very pleased with the home that was left for them by the Expedition Two guys."

Usachev and Culbertson shake hands aboard the station. Photo: NASA TV/Spaceflight Now

The milestone event that marks the change of home spacecraft for the Expedition astronauts is the transfer of custom-fitted seatliners for the Soyuz emergency escape capsule from the shuttle to the station. With the seatliners moved, each Expedition Three astronaut will officially become an Alpha resident, allowing the Expedition Two crew to head over to Discovery.

The timeline calls for Culbertson's seatliner to be moved starting at 8:10 a.m. EDT to replace Susan Helms, followed by Dezhurov's at 10:10 a.m. EDT to replace Usachev and Tyurin's at 1:30 p.m. to replace Voss.

Also on tap Monday will be the mounting of the Italian-made Leonardo cargo module to the space station so the astronauts can unload its 6,400 pounds of food, clothing, supplies and scientific equipment needed by the Expedition Three crew. The shuttle's robot arm will lift the module out of Discovery's payload bay and attach it to the nadir port on the Unity connecting node.