14 DAY TRIAL // The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) weather-observing satellite has been in orbit since April 2006, and has continuously fired its laser at the planet's atmosphere ever since. Still, after three years of performing admirably, especially as part of the “A-Train” satellite constellation, its main laser has shut down recently, prompting mission controllers to upload a new program on the probe, instructing it to deploy its back-up instrument. It did so seamlessly, and only a ten-day gap in data was recorded.
“We designed the system with the ability to change to a back-up laser,” NASA's CALIPSO Project Scientist Chip Trepte, from the American space agency's Langley Research Center, said. “Early this year the [primary] laser started showing unstable behavior consistent with low canister pressure. We therefore decided to turn on the back-up laser,” CALIPSO Mission Operation Manager Nadege Queruel, from the French space agency Centre National d'Etudes Spatiales (CNES), explained.
The move didn't catch anyone by surprise, as the unstable parameters sent back by CALIPSO on its primary laser were unambiguous. And a satellite of its type, mission experts say, is virtually blind without its laser.
Queruel added that, “We were aware before launch in 2006 that the pressure canister that housed the primary laser had a slow leak. But we were sure that it could still complete the three-year prime mission.” The main goal of the spacecraft was to fly in tandem with four to five other observatories (the A-Train Satellite Constellation), and to create vertical profiles of Earth's atmosphere.
The purpose was to identify the amount of aerosols that existed in the air, as well as their sources. Usually, human pollution, wildfires, and other natural processes cause the largest amounts of particles and aerosols in the air.
“The good news is we turned on the second laser that had been idle for 3 years, and it’s working as well as the primary laser did early in the mission. The pressure in the second laser canister is quite high, and it should be able to operate for many more years,” Trepte shared.
CALIPSO was the result of a collaboration between NASA and CNES, and the instrument itself was constructed in France, at the Cannes Mandelieu Space Center. It was launched from the Vandenberg Air Force Base's (VAFB) Launch Pad SLC-2W, on April 28th, 2006 (along with the CloudSat observatory), aboard a Delta II delivery system.