NASA Scrubs Launch of CloudSat, CALIPSO Satellites
NASA's Cloudsat (upper left) and Calipso weather satellites show in this artist's rendition are set to launch into orbit next month.
Credit: NASA.

Two NASA satellites are stuck on Earth for at least one more day after a last minute glitch prevented an early Friday launch.

The space agency's CloudSat and CALIPSO Earth weather satellites were just 48 seconds from riding a Boeing-built Delta 2 rocket spaceward from California's Vandenberg Air Force Base when launch officials called off the attempt. Another attempt could occur as early as Saturday, NASA said.

NASA spokesperson Bruce Buckingham said the CALIPSO satellite - a spacecraft built for NASA and the French Space Agency (CNES) - lost both primary and backup communications with its French support center, prompting the launch scrub.

"The communications links went down simultaneously," NASA launch commentator Bruce Buckingham said, adding that the links were required to proceed with the launch.

While launch controllers were later able to reestablish contact between CALIPSO - which sits above CloudSat aboard their Delta 2 rocket - the delay prevented the two spacecraft from catching their launch window at exactly 6:02:08 a.m. EDT (1002:08 GMT). The satellites are now being readied for an April 22 launch at 6:02:26 a.m. EDT (1002:26 GMT), NASA officials said.

The CloudSat and CALIPSO - short for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations - are both aimed at providing a new three-dimensional view of Earth's clouds and aerosols, which are fine particles suspended in the atmosphere.

CALIPSO carries a lidar laser ranging instrument to identify and measure aerosols, as well as two other instruments. CloudSat, meanwhile, is equipped with a powerful radar to scan clouds layer by layer and pick apart the cloud, water and snow components.

"We carry a 90 gigahertz radar, the first-ever to be flown in space" CloudSat mission director Ron Boain said just before today's launch scrub.

CloudSat and CALIPSO are expected to fly in a 438-mile (705-kilometer) orbit in formation with three other Earth watching satellites already in space to make up the "Afternoon Train" (A Train).

Together with France's PARASOL satellite and NASA's Aqua and Aura spacecraft, the two new probes will build a comprehensive, three-dimensional picture of Earth's weather, climate change and possibly the human contributions to the greenhouse effect and global warming, mission scientists said.

The $185 million CloudSat and $223 million CALIPSO probes are expected to spend three years observing the Earth once they reach orbit, NASA said.