Satellite to track polar 'night-shining' clouds

Last Updated: Friday, April 27, 2007 | 12:31 PM ET

CBC News

Scientists hope a recently launched spacecraft can help shed light on mysterious ice clouds on the edge of space over Earth's polar regions that they think could be linked with global warming.

NASA launched the Aeronomy of Ice in the Mesosphere (AIM) spacecraft on Wednesday, the first probe to go into space to study the phenomenon of noctilucent clouds — or "night-shining" clouds.

The high-altitude clouds can can only be seen at night, after the sun has dipped below the horizon enough that lower atmosphere clouds can no longer be seen behind the Earth's shadow. They shine a ghostly blue about 80 kilometres above the ground.

"Noctilucent clouds are increasing in number, becoming brighter and are occurring at lower latitudes than ever before," said principal investigator James M. Russell of Hampton University in Hampton, Va.

"Such variations suggest a connection with global change," said Russell. "If true, it means that human influences are affecting the entire atmosphere, not just the region near the Earth's surface."

The spacecraft will begin scientific operations after two weeks of testing and then spend two years collecting data from the icy clouds, taking high-altitude photographs and measuring their size, air pressure, temperature and moisture content.

The spacecraft was mounted on a Pegagus rocket carried aloft by a special aircraft and launched into a polar orbit 600 km above the Earth.

Noctilucent clouds were first noticed in 1885, about two years after the eruption of the volcano Krakatoa sent plumes of volcanic ash into the Earth's atmosphere.