Lidar Satellite Resumes Data Collection

Daniel S. Burgess

NASA's Ice, Cloud and land Elevation Satellite is again collecting information on the topography of the Earth's ice sheets; the heights, thicknesses and other properties of cloud and aerosol layers; and the topography of the planet's surface. The primary mission of the craft's Geoscience Laser Altimeter System is the collection of data for more-accurate prediction of the changes in sea level that may accompany global warming.

NASA's Ice, Cloud and land Elevation Satellite has resumed operation. The craft's laser altimeter offers information on the polar ice sheets, on cloud height and on the Earth's topography.

Launched in January, the first of several lasers on the satellite ceased functioning 36 days into the multiyear mission. NASA scientists have investigated the causes of the temporary problem.

The altimeter system features three diode-pumped Q-switched Nd:YAG lasers, a 1-m beryllium receiver telescope and silicon avalanche photodiode detectors. The lasers produce 4-ns-long pulses of 1064- and 532-nm radiation at a rate of 40 Hz to determine elevations at 170-m intervals over the surface of the planet.

In late October, the satellite observed the smoke emitted from the wildfires in California. Such studies of large-scale biomass burning around the globe will enable scientists to better understand how winds transport smoke from burning biomass and how the smoke mixes with clouds to influence atmospheric heating from the absorption of solar radiation.