November 12, 2012
Orbiting Satellites Could Be Affected By Climate Change
Lee Rannals for redOrbit.com — Your Universe Online
Scientists wrote in the journal Nature Geoscience that rising carbon dioxide (CO2) levels could increase the accumulation of space junk. And as CO2 builds up in the upper levels of Earth's atmosphere it could have a significant effect on satellites in orbit.CO2 cools down the atmosphere and contracts its outermost layer, the thermosphere, which is where satellites and the International Space Station (ISS) operate.
A contracted thermosphere reduces atmospheric "drag" on satellites, causing satellite orbits to change, drawing them closer to Earth. With this in effect, orbiters like the ISS have to boost themselves back on course.
"The observed CO2 increase is expected to gradually result in a cooler, more contracted upper atmosphere and a consequent reduction in the atmospheric drag experienced by satellites," the US Naval Research Laboratory, which took part in the study, wrote in a statement.
The scientists said that the effects of growing CO2 could slow the rate at which debris burns up in the atmosphere, and potentially make the atmosphere less effective in burning meteors up before they break through to Earth.
Space expert Hugh Lewis said that a cooler troposphere will extend the lifetime of space junk, staying farther out for longer instead of burning up in the lower layers of the atmosphere.
"Consequently, space junk will accumulate at a faster rate and we will see more collisions between space objects as a result," he told AFP. "We will also see many more 'near-misses' and these have an important effect on spacecraft operators."
Although there wouldn't be an increased risk for those on Earth, humans could see some effects on services provided from space.
A 2011 NASA study found that there were more than 22,000 pieces of space debris larger than 4-inches orbiting around the Earth.
Even the smallest pieces of debris can have harsh damage on satellites, and could be deadly for astronauts aboard the International Space Station. Space debris just half-an-inch in diameter floating at 21,600 mph could do as much damage as a 400-pound safe traveling at 60 mph.
The researchers wrote that thermosphere density trends calculated from satellite orbits suggested that the cooling influence was larger than computer models predicted. They said the new carbon measurements, which also outpace projections, may help to explain that discrepancy.