By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - NASA on Sunday gave up waiting for weather to clear for U.S. space shuttle Atlantis to land in Florida, diverting it to California after a 13-day mission to refurbish the Hubble Space Telescope.
Flying over Africa, Atlantis commander Scott Altman and pilot Greg Johnson fired their spaceship's twin braking rockets to leave orbit and begin an hour-long glide to Edwards Air Force Base in California's Mojave Desert.
Touchdown is scheduled for 11:39 EDT (4:39 p.m. British time).
NASA had planned to bring Atlantis back to its home in Florida on Friday but was stymied by cloudy skies and rain over the Kennedy Space Centre.
The U.S. space agency prefers to land at the Florida launch site to save the time, money and risk of ferrying the shuttle cross-country atop a 747 jet carrier.
Flight directors tried again to land Atlantis in Florida on Sunday but were concerned that offshore rain would drift to within 30 nautical miles of the runway at the time of the shuttle's landing.
Flight directors took another look at the weather as Atlantis circled the planet one more time before diverting to California.
"The Edwards weather is great, it's clear," astronaut Greg Johnson from Mission Control in Houston radioed to the crew.
"Copy that, beautiful day in the desert," replied Altman.
The shuttle is returning from NASA's fifth and final servicing mission to Hubble before the shuttle fleet is retired next year.
UPGRADED HUBBLE
The observatory, launched in 1990, has provided key evidence of the existence of dark energy, a still-unexplained force that is expanding space at an increasingly faster rate, and the existence of galaxies far earlier than scientists thought possible.
Atlantis' 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 crew also left Hubble with a docking ring so a future spacecraft can latch on and drive it into the sea when its operational lifetime is over.
The U.S. space agency hopes that with the upgrades Hubble will have another five to 10 years for cutting edge scientific observations.
The first images from the repaired and upgraded observatory are expected in September.
(Editing by Tom Brown and Alan Elsner)
