This year has proved to be an important one for NASA, as it has retired two of the three remaining operational orbiters in its Space Shuttle fleet. Space shuttle Discovery made its final mission in February, and Space shuttle Endeavour completed its last jaunt in June. On July 8, the third and final spacecraft, Space shuttle Atlantis, launched into space one last time before its retirement as well. 

Now, NASA is happy to announce that Atlantis made its final docking at the International Space Station (ISS) on Sunday. Two hours after docking, the four-person crew, which consists of Commander Chris Ferguson, Pilot Doug Huley and Mission Specialists Sandy Magnus and Rex Walheim, entered the ISS to hug and take pictures with the six-person crew in the ISS. With NASA retiring its Space Shuttle fleet, this was an important moment in NASA history, as it may be awhile before another launch takes place.

While Atlantis arrived safely to the ISS, the trip up until that point wasn't entirely smooth. Before docking, one of the shuttle's computers failed during a morning power-up. According to Atlantis' Lead Flight Director Kwatsi Alibaruho, the on-off switches need to be flipped on a certain way, otherwise they cause a glitch. The computer was taken offline, allowing the remaining two computers, which work simultaneously for the sake of redundancy, to take over. The shuttle also has two spare computers if needed. 

In addition, Atlantis' mission management Team Leader LeRoy Cain noted that a piece of space junk is expected to come close to the ISS and shuttle on Tuesday, but it is not 100 percent confirmed yet. Cain also was unsure of the size of the piece of space junk, but said that Atlantis could "fire its thrusters to move the station out of the way."

Despite these minor troubles, Atlantis has docked and plans to continue doing what the crew went there to do: resupply the ISS. The 12-day mission (which may now be a 13-day mission due to extra time needed for moving cargo), STS-135, is delivering spare parts, clothes, food and experiments via the Raffaello multipurpose logistics module. The supplies are expected to last through the end of 2012.

Today, the crew is using the station's robotic arm to move the Raffaello multipurpose logistics module out of the shuttle's payload bay and connect it to the ISS to retrieve the cargo. A spacewalk is scheduled for Tuesday, but most of the trip will require the moving of cargo and extra help around the ISS.

While many see the retirement of the Space Shuttle fleet as the end, NASA Administrator Charles Bolden assures that NASA is only retiring the "launching-to-orbit business," but has big plans for the future.

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