This story was updated at 2:23 p.m. EST.

HOUSTON — With warm words and embraces, the seven astronauts of NASA's shuttle Atlantis bid farewell to their counterparts aboard the International Space Station (ISS) Sunday as they prepare to head home after delivering a new European lab.

Shuttle commander Stephen Frick and his crewmates said their goodbyes to the station's three-person crew after a busy week installing the new 10-ton Columbus laboratory and ferrying a new crewmember to the orbiting outpost.

"It's an amazing place, vastly different than when we were last up here," said Frick, who last visited the station with STS-122 crewmate Rex Walheim in 2002, during a farewell ceremony. "We were privileged to bring up the European Columbus module."

During their time on station, Atlantis astronauts attached the European Space Agency's (ESA) Columbus lab to the station's hub-like Harmony node and outfitted it with experiments during three spacewalks. They will undock early Monday for a planned landing on Wednesday morning.

But before astronauts shut the hatches between their spacecraft at 1:03 p.m. EST (1803 GMT), they made sure to replace U.S. astronaut Dan Tani with ESA astronaut Leopold Eyharts, of France, as Expedition 16 flight engineers.

The hatch closure will mark a milestone for NASA astronaut Dan Tani, whom Eyharts replaced as an ISS Expedition 16 flight engineer. Tani will return to Earth aboard Atlantis after spending two extra months in space due to the shuttle flight's delays.

"It's a great day for me," said Tani, who arrived at the station in late October and will return home aboard Atlantis.

Delays to Atlantis' launch attempts in December extended his flight by two extra months, during which time his 90-year-old mother Rose died in a car accident outside of Chicago.

"The other thing I was thinking about is my mother — my inspiration," a tearful Tani said, adding that he's looking forward to seeing wife Jane and two daughters after landing. "Jane is the love of my life and she had the hard work while I was having fun."

All packed up

Atlantis astronauts and the station?s Expedition 16 crew spent their final hours of joint work wrapping up the outfitting of the ESA's 1.4 billion euro ($2 billion) Columbus laboratory and packing up cargo for the trip back to Earth.

"The mission has gone, by many measures of success, extremely smoothly," said Bob Dempsey, NASA's lead ISS flight director for the 13-day spaceflight.

Columbus is a 23-foot (7-meter) long research module with an interior volume 14.7 feet (4.5 meters) wide and represents the ESA's largest single contribution to the multinational ISS project.

"The Columbus module is attached, it's activated and it's working very well," said ESA station program manager Alan Thirkettle.

Astronauts spent Sunday morning activating some of the new lab's science racks and transferring last-minute ISS biological experiment samples into cold bags for the trip back to Earth.

"I have a feeling of a very big sense of accomplishment," said Eyharts, who will complete Columbus' commissioning during his month-long stay on the station. "We have a really international space station."

Tani said he is leaving some notes aboard the station for future crewmembers, including advice on how to handle a family tragedy like the death of his mother.

"Living up here is just fantastic and I'm going to miss floating and I'm going to miss looking out the window," Tani said last week. "I'm just packing and making sure that I don't forget anything."

Station commander Peggy Whitson said she and Expedition 16 flight engineer Yuri Malenchenko will miss Tani, especially after his extended stay.

"Dan has done just a phenomenal job," Whitson said.

By Saturday, Atlantis astronauts had delivered more than 1,386 pounds (628 kg) of water to the space station and used the shuttle's supplies to repressurize the orbiting outpost's atmosphere, Dempsey said today.

They pumped about 90 pounds (41 kg) of oxygen from Atlantis to high-pressure tanks aboard the station for use in future spacewalks and will return about 2,040 pounds (925 kg) — the most ever tucked aboard a shuttle's middeck — back to Earth, he added.

Atlantis fired its rocket engines for about 36 minutes early Saturday to raise the space station's orbit by about 1.24 miles (2 km), boosting its speed by about 1.6 meters per second, or about 3.5 mph. The maneuver left the station at an altitude of about 210 miles (337 km) and in a better position to receive NASA's shuttle Endeavour next month on another construction flight next month, as well as a Russian Soyuz spacecraft to launch on April 8.

"All the systems on the orbiter continue to function well," Dempsey said.

Atlantis is scheduled to undock from the ISS on Monday at 4:27 a.m. EST (0927 GMT) and land Wednesday at 9:07 a.m. EST (1407 GMT) on a runway at NASA's Kennedy Space Center in Cape Canaveral, Fla.

The space agency will also activate a backup runway at California's Edwards Air Force Base to give Atlantis an extra landing opportunity on Wednesday to clear the way for the U.S. military to shoot down a failing spy satellite laden with toxic rocket fuel before it enters the Earth's atmosphere.

NASA is broadcasting Atlantis' STS-122 mission live on NASA TV. Click here for SPACE.com's shuttle mission coverage and NASA TV feed.