At Mission Control on Sunday, lead flight director Kwatsi Alibaruho declared “this is it” as he gave the OK for the final docking in space shuttle history. Flashbacks to the shuttle’s very first space station docking — with Russia’s Mir in 1995 — flooded his mind as viewed the shuttle on the scree

ns. He was a NASA trainee back then.

About 240 miles above the Pacific, the station’s naval bell chimed a salute — one of many landmarks, or rather spacemarks, of this final two-week shuttle mission that are being savored one by one.

“Atlantis arriving,” called out space station astro

naut Ronald Garan Jr. “Welcome to the International Space Station for the last time.”

“And it’s great to be here,” replied shuttle commander Christopher Ferguson.

Cries of joy and laughter filled the connected vessels once the hatches swung open and the two crews — 10 space fliers altogether representing three countries — exchanged hugs, handshakes and kisses on the cheek. Cameras floated everywhere, recording every moment of the last-of-its-kind festivities.

Atlantis, carrying a year’s worth of supplies, is being retired after this flight, the last of the 30-year shuttle program.

“I won’t say that I got close to welling up in the eyes, but I will say that it was a powerful moment for me,” Alibaruho later told reporters. He tried to keep his feelings discreet so as not to distract his team of flight controllers, but said, “I know they were all feeling very similar emotions, thinking about where we’ve come from, how much we’ve accomplished … what’s coming next.”

Alibaruho said the moment was also powerful for the 10 people in space for the docking: six Americans, three Russians and one Japanese.

“You could sense a palpable increase in emotion from all of the crew members, not just our U.S. astronauts,” he said. “They were extremely happy and really elated to see their visitors, and I know that they really recognize and appreciate the significance of these moments.”

A computer failure aboard Atlantis took away some of the redundancy desired for the rendezvous, but did not hamper the operation.

Within a few hours, though, news came that NASA was monitoring a piece of space junk that could come dangerously close to the orbiting shuttle-station complex on Tuesday — right in the middle of a spacewalk.

Mission management team chairman LeRoy Cain stressed it was still too soon to know whether the unidentified object would truly pose a threat, and that a decision would be made Monday as to whether the linked spacecraft would have to move out of harm’s way. The size of the object was not immediately known.

This was the 46th docking by a space shuttle to a space station.

Nine of those were to Mir back in the 1990s, with Atlantis making the very first. The U.S. and Russia built on that sometimes precarious experience to create, along with a dozen other nations, the world’s largest spacecraft ever: the permanently inhabited, finally completed, 12½-year-old International Space Station.

This time, Atlantis is delivering more than 5 tons of food, clothes and other space station provisions — an entire year’s worth, in fact, to keep the complex going in the looming post-shuttle era.

The shuttle astronauts quickly handed over a bag of groceries loaded with fresh fruit and promised the station residents some extra jars of peanut butter. “Outstanding,” said inhabitant Michael Fossum.

Ferguson was at the controls as Atlantis drew closer, leading the smallest astronaut crew in decades.

Only four are flying aboard Atlantis, as NASA kept the crew to a minimum in case of an emergency. In the unlikely event that Atlantis was seriously damaged, the shuttle astronauts would need to move into the space station for months and rely on Russian Soyuz capsules to get back home. A shuttle always was on standby before for a possible rescue, but that’s no longer feasible with Discovery and Endeavour officially retired now.

Two days into this historic voyage — the 135th in 30 years of shuttle flight — Atlantis was said by NASA to be sailing smoothly, free of notable damage. Sunday’s docking proved to be as flawless as Friday’s liftoff.

As a safeguard, Atlantis performed the usual backflip for the space station cameras, before the linkup. The station astronauts used powerful zoom lenses to photograph all sides of the shuttle. Experts on the ground will scrutinize the digital images for any signs of damage that might have come from fuel-tank foam, ice or other launch debris.

Atlantis and its crew will spend more than a week at the orbiting complex. The shuttle flight currently is scheduled to last 12 days, but NASA likely will add a 13th day to give the astronauts extra time to complete all their chores.

As for the shuttle’s failed computer, Alibaruho said a bad switch throw likely knocked it offline. He expects it to be working again once new software is installed Monday.

NASA is getting out of the launching-to-orbit business, giving Atlantis, Endeavour and Discovery to museums, so it can start working on human trips to asteroids and Mars. Private U.S. companies will pick up the more mundane job of space station delivery runs and, still several years out, astronaut ferry flights.

NASA Administrator Charles Bolden stressed in an interview with CNN’s “State of the Union” program Sunday morning that the United States will remain the world leader in space exploration, even after the shuttles stop flying.

“I would encourage the American public to listen to the president,” Bolden said. “The president has set the goals: an asteroid in 2025, Mars in 2030. I can’t get any more definitive than that.”