Rising CO2 levels in atmosphere causes space jam, scientists warn

PUBLISHED : Tuesday, 13 November, 2012, 12:00am
UPDATED : Tuesday, 13 November, 2012, 2:56am

A build-up of carbon dioxide in the upper levels of the earth's atmosphere risks causing a faster accumulation of man-made space junk, which could cause more collisions, scientists warn.

While on earth it causes warming, CO2 conversely cools down the atmosphere and contracts its outermost layer - the thermosphere - where many satellites, including the International Space Station (ISS), operate, found a study published in the journal Nature Geoscience.

A contracted thermosphere, in turn, reduces atmospheric "drag" on satellites - a similar force to that experienced when holding one's hand out the window of a moving car.

This drag is what causes satellite orbits to change, drawing them closer to Earth, which means orbiters, such as the ISS, have to use on-board engines to boost themselves back on course.

"The observed CO 2 increase is expected to gradually result in a cooler, more contracted upper atmosphere and a consequent reduction in the atmospheric drag experienced by satellites," said the Naval Research Laboratory, which took part in the study.

Space expert Hugh Lewis said a cooler troposphere will extend the lifetime of space junk - staying farther out for longer instead of burning up lower in the atmosphere, closer to Earth.

Lewis said there would be no increased risk for us on earth.

"However, we would see some effects on services provided from space if an important satellite was destroyed by a collision," he said.

On the positive side, the change means satellites would no longer need to boost themselves back into orbit quite as often, meaning they can carry less fuel.