NASA Satellite Switches to Second Laser
The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission is now operating on its redundant laser, which was designed as a contingency in case of a problem with the primary laser. A slow pressure leak in the canister that housed the primary laser, which the CALIPSO team had been aware of since launch, made the switch necessary. The backup laser, which stood ready for nearly three years, sent back its “first light” image on
CALIPSO makes unique vertical profile measurements of clouds and aerosols. Aerosols are suspended particles from fires, industrial activities and natural processes that are one of the least understood weather and climate variables. CALIPSO’s lidar instrument measures the altitude and thickness of aerosol and cloud layers in the atmosphere. It also measures particles’ size, whether they are spherical or non-spherical and whether they are composed of water or ice. CALIPSO’s observations complement data recorded by four other satellites flying in formation called the A-Train, which provide an unprecedented comprehensive global view of atmospheric chemistry and composition within eight minutes of one another over the same ground track.
First operational in
The CALIPSO team became aware before launch that the pressure canister that housed the primary laser had a slow leak. The decision to launch was made because it was expected the primary laser could still complete the three-year prime mission. If it could not, the back-up instrument could take over. Early this year the laser showed unstable behavior consistent with low canister pressure. An investigation determined that turning on the backup laser now was the best solution.
“We designed the system with the ability to change to a back-up laser,” said
“The good news is we turned on the second laser that had been idle for three years, and it’s working as well as the primary laser did early in the mission,” Trepte said. “The pressure in the second laser canister is quite high, and it should be able to operate for many more years.”
Throughout the CALIPSO mission, NASA and CNES have worked closely, from developing the mission, building the satellite platform and integrating the payload to monitoring the instrument and processing its valuable measurements.
“Even though we are on each side of the Atlantic, we work as a single, integrated NASA-CNES team,” said Nadege Queruel, mission operations manager with the CNES team.
CALIPSO is a joint effort between NASA and CNES. NASA and Ball Aerospace designed the lidar instrument; CNES and Thales Alenia Space, previously Alcatel Space, built the Proteus satellite platform.
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