Bad Weather Forces Edwards Landing of Shuttle Endeavour : NASA: The space plane ends a productive 11-day mission by scrapping a planned touch-down at Kennedy Space Center.

After bad weather in Florida twice prevented a hoped-for landing at the Kennedy Space Center, the space shuttle Endeavour returned to Earth here Wednesday, ending an 11-day mission that garnered reams of data on changes in the Earth’s environment.

“The radar lab has provided an unprecedented view of our planet,” a mission control announcer at the Johnson Space Center in Texas told the six astronauts aboard Endeavour as it came to a stop on concrete Runway 22. “Welcome home.”

In all, enough data was recorded during the journey, dubbed “Mission to Planet Earth,” to fill 20,000 encyclopedia volumes. About 12% of the Earth’s surface, more than 70 million square kilometers of land and sea, was mapped during the flight.

The Earth-observing instruments met scientists’ “highest expectations, collecting unique imagery of important environmental sites around the globe,” according to the National Aeronautics and Space Administration.

Endeavour touched down with its payload of sensitive radar equipment and six astronauts a few minutes before 10 a.m. in what a NASA announcer described as “virtually pristine” weather conditions at Edwards Air Force Base on the edge of the Mojave Desert.

The picture-perfect landing under a cloudless sky left Endeavour with what appears to be heavier than normal wear on its nose gear tires, something that will need further evaluation, NASA spokesman Don Haley said.

The California landing, the first since the shuttle Columbia landed here Nov. 1, means that Endeavour will have to be ferried back to Florida atop a modified 747, adding more than $1 million to the cost of the mission.

Because it was an unscheduled landing, few others besides those who work at Edwards Air Force Base were on hand to watch Endeavour’s return. Only a few people were at NASA’s hillside viewing site, a VIP area that is usually packed during a scheduled shuttle landing. There are no scheduled shuttle landings at Edwards in 1994.

The Endeavour mission was planned for nine days, but early into the flight was increased by a day “because of abundant supplies,” according to NASA. The first landing attempt in Florida on Tuesday was canceled because of cloud cover and poor runway visibility. Poor weather there Wednesday morning forced the California landing.

Endeavour, which has now completed six missions, is expected to be returned to the Kennedy Space Center on Monday morning, Haley said. The orbiter’s next flight is scheduled for August. It will carry the same radar equipment as on the just completed mission.

Within hours of the April 9 launch, the radar equipment in the shuttle’s payload bay was activated and continued to collect data without interruption throughout the mission, NASA officials said.

Data was gathered from points around the world, ranging from Mammoth Mountain in California to the forests of the Amazon in Brazil to the Kamchatka Peninsula in Russia, as the shuttle orbited the Earth every 89 minutes, traveling more than 4.7 million miles.

In orbit about 135 nautical miles above the Earth’s surface, the radar equipment was able to penetrate the dry sand cover of the Sahara Desert to reveal drainage patterns hundreds of years old.

Data on the amount and distribution of carbon monoxide in the atmosphere was collected to aid in determining “how well the atmosphere can clean itself of ‘greenhouse gases,’ chemicals that can increase the atmosphere’s temperature,” according to NASA.

The radar instruments were also used to observe flooding in Missouri and Germany, as well as the San Andreas fault. Astronauts supplemented the vast radar data by taking more than 14,000 still photographs.

During the flight, mission specialist Jay Apt used amateur radio equipment to have an in-space chat with Russian cosmonauts aboard the MIR space station. Apt also used the equipment to talk with two American astronauts and a pair of cosmonauts who were at the Star City training center near Moscow.