Laser System to Measure Air Pollution from Space Station

A laser system aboard the International Space Station will help scientists track pollution in the atmosphere.

The Cloud-Aerosol Transport System (CATS), to be launched later this year, will measure atmospheric particles using photodetectors and near-infrared (1064 nm), visible (532 nm) and UV (355 nm) lasers firing at 5000 pulses per second.

The device is intended to operate for at least six months and up to three years aboard the Japanese Experiment Module-Exposed Facility, augmenting measurements gathered by NASA’s CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission, which emits 20 pulses per second at the NIR and visible frequencies.

Roughly the size of a refrigerator, CATS will use three laser wavelengths to provide more detailed information about particles in Earth’s atmosphere. Courtesy of NASA.

“What we’re trying to determine is whether the addition of the third wavelength — 355 nanometers, which is in the ultraviolet — will produce the results we expect it to generate,” said Goddard Space Flight Center scientist Matt McGill, who led the team that designed the CATS system. “We believe it will deliver more detailed information revealing whether the particles scientists see in the atmosphere are dust, smoke or pollution.”

The UV optics may be particularly susceptible to damage caused by contamination, however. “You end up with very limited lifetime,” McGill said. “The way to find out is to fly a relatively inexpensive payload aboard an existing platform, like the International Space Station.”

The space station’s precessing orbit, which shifts from 51° north latitude to 51° south latitude, will provide good coverage of what’s happening in the atmosphere over most population centers. It will also provide views of two major aerosol-transport paths: one that stretches in an inverted U shape from Japan down the West Coast of the U.S. and another that moves from western Canada to the Great Lakes and the East Coast.

Long-term data could reveal shifts in global climate, such as whether changes are occurring in cloud cover or whether the level of pollutants is increasing or decreasing.

For more information, visit www.nasa.gov.