It's The Global Warming, Man

Scientists report carbon dioxide emissions from fossil fuels are helping to keep orbiting spacecraft airborne longer, by reducing atmospheric drag. There's no such thing as a free lunch, though... for the same effect also increases the threat that space junk poses to satellites.

Stanley Solomon, a senior scientist at the National Center for Atmospheric Research, presented his group's results at an American Geophysical Union meeting in San Francisco earlier this month.

The air density of the outer atmosphere was reduced about five percent over the past 30 years, according to Solomon's computer model estimates. That figure could decrease 40% by the end of the century, he added.

Solomon noted that a less dense atmosphere should not be a problem in the near-term, but could be a significant issue in the future, especially with the increase of space junk left from space missions, old satellites, and other space debris left circling the earth.

"In the long haul, it means we have to be even more assiduous about not letting miscellaneous pieces of metal float about," Solomon said.

Additionally, forecasts of outer atmosphere density could help NASA and other agencies plan the fuel needs and timing of satellite launches.

Solomon's conclusions mirror prior research predicting similar effects.

The hypothesis that carbon dioxide emissions would affect the thermosphere was advanced in 1989 by Robert Dickinson and others, and the change in density was recently measured by analyzing changes in satellite orbits.

FMI: www.ncar.ucar.edu/  www.agu.org/