By Steve Gorman
EDWARDS AIR FORCE BASE, California (Reuters) - U.S. space shuttle Atlantis capped an extended 13-day mission to rejuvenate the Hubble Space Telescope on Sunday with a flawless landing at Edwards Air Force base in California.
The touchdown under clear blue skies came at 11:39 EDT (4:39 p.m. British time) after foul weather stymied two days of landing attempts at the Kennedy Space Centre in Florida.
"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," radioed astronaut Greg Johnson from Mission Control in Houston.
"It was a thrill from start to finish," replied Atlantis commander Scott Altman.
Altman and pilot Greg Johnson began the hour-long glide back to Earth by firing Atlantis' twin braking rockets to leave orbit, shedding 257 feet per second (78 metres per second) to align the ship for a fiery freefall through the atmosphere.
The Atlantis astronauts were the fifth and final crew to work on the Hubble telescope, which was launched in 1990.
An initial servicing mission in 1993 fixed a problem with the telescope's prime mirror, giving Hubble a unprecedented view of the universe. Its observations have provided evidence of galaxies that formed far sooner than scientists thought possible and of the existence of supermassive black holes at the centres of most galaxies.
The astronauts outfitted Hubble with an even more sensitive camera that should be able to image objects formed 500 million years after the birth of the universe.
During five challenging spacewalks, they also installed a light-splitting spectrograph to analyse the chemical composition of matter between the galaxies, repaired two broken instruments and replaced the telescope's positioning gyroscopes and batteries.
The U.S. space agency hopes that with the upgrades Hubble will have another five to 10 years for cutting edge scientific observations.
(Additional reporting by Irene Klotz at Cape Canaveral; Editing by Tom Brown and Alan Elsner)
