The U.S. space shuttle Atlantis has landed in the western U.S. state of California, ending an unprecedented 13-day mission to upgrade the Hubble Space Telescope. The U.S. space agency NASA declared the complex repair job a total success, saying it should extend the life of the 19-year old telescope by at least five years.

Five days after finishing work on the Hubble space telescope, the seven astronauts on the space shuttle Atlantis finally returned to Earth, two days later than originally planned.

"Houston: Atlantis wheel stop, Edwards 22."

"Welcome home Atlantis! Congratulations on a very successful mission, giving Hubble a new set of eyes that will continue to expand our knowledge of the universe."

"Thank you, Houston, it was a thrill from start to finish. We have had a great ride."

Atlantis touched down Sunday at Edwards Air Force base in California. NASA had wanted to land the shuttle on Friday at its home base of Florida in the east, but scrapped the plan due to bad weather.

Transporting the shuttle back to Florida will cost nearly $2 million.

NASA experts praised the crew members for overcoming a series of obstacles in their five space walks. The astronauts installed new instruments on Hubble, repaired others that stopped working and replaced its dying batteries.

NASA's head of space science, Ed Weiler, says initial examinations of the telescope indicate the mission was a success.

"The people at Goddard [Goddard Space Flight Center] and the Space Telescope Science Institute have not been sitting on their hands, they are already in the process of checking out the instruments," said  Ed Weiler. "Everything is going very smoothly, no problems so far."

Since it began orbiting the Earth in 1990, Hubble has provided much more information about the universe than land-based telescopes, whose images are distorted by the Earth's atmosphere.

NASA says the upgrade will allow Hubble to peer even deeper into the universe until at least 2014. But the agency says the latest repair mission is likely to be the last, because it plans to retire the shuttle fleet next year.

Weiler urged reporters at a news conference not to focus on the negative.

"I mean, geez! We just repaired the Hubble space telescope," he said. "We got a new telescope - four new instruments - two of them dead, now alive! We have got another five, six, seven, eight years with a new telescope. These are truly the best of times, not the worst of times!"

NASA expects to release the first data from the upgraded Hubble by the end of August.