NASA’s first geosynchronous satellite.
The build-up of greenhouse gasses in the atmosphere is predicted to have a number of effects here on Earth: record high temperatures, unprecedented droughts, and stronger than normal storms. But the effects may also extend to what’s far, far above us. Hydrogeologist Scott K. Johnson writes at Ars Technica that the “non-intuitive” consequences of climate change will be significant, including, potentially, screwing with the paths of satellites circling the Earth. Here’s how:
As humans, we really only experience the lower atmosphere—the troposphere and stratosphere that extend about 30 miles from the surface. That’s where nearly all of the gas in the atmosphere resides, and that’s where weather happens. Even Felix Baumgartner, the daredevil skydiver, “only” jumped from the stratosphere. But technically, the atmosphere extends a whole lot higher than that. It’s another 150 miles or so before we truly reach interplanetary space. A number of satellites, as well as the International Space Station, are actually whizzing around in a layer of the atmosphere called the thermosphere.
Down in the troposphere, CO2 is an important greenhouse gas. Add more CO2, and you trap more outgoing heat, warming the lower atmosphere. But up in the thermosphere, things are much different. Gas molecules are incredibly sparse—and increasingly so as you head outward from the Earth. Here, CO2 is actually a key coolant, as it absorbs energy from collisions with oxygen molecules, and then emits that energy as infrared radiation, sending much of it out into space.
Rising CO2 levels cause the thermosphere to cool and contract, thus reducing drag on objects orbiting in this layer of the upper atmosphere. The end result will be a speeding up and slight change of course for satellites and already unstable space debris. And if thermospheric CO2 levels continue to rise, as they are predicted to do, Johnson suggests that astronomers will have to monitor and make adjustments to account for these changes in trajectory in order to avoid more serious consequences.
Read more at Ars Technica.
Image courtesy of NASA