Orbital debris is a troubling issue for operating satellites - Credit: CNES
BOULDER, Colorado – The Earth is encircled by menacing, human-made orbital debris. A new study suggests that long-term change in the Earth’s atmosphere is causing satellites – and troublesome space junk – to stay in orbit for longer than expected.
A research team from the University of Southampton in the United Kingdom has found that a contraction of the Earth’s thermosphere — the biggest of all the layers of our planet’s atmosphere directly above the mesosphere and directly below the exosphere — has been attributed to the build-up of greenhouse gases, such as carbon dioxide.
That contraction is tied to a drop in the thermosphere’s temperature. Therefore, there is a corresponding decrease in density of that layer.
According to lead researcher at the university, Hugh Lewis, that decrease of atmospheric density may well impact upon the effectiveness of removing space debris – which consists of human-made objects such as redundant satellites, tossed away rocket bodies and other clutter – from orbit.
Approximately 19,000 objects larger than 10 centimeter are known to exist in Earth orbit and less than 10 percent of these are operational payloads, with the remaining population classed as space debris.
These objects represent a significant risk to satellite operations, due to the possibility of damaging or catastrophic collisions, as demonstrated by the run-in between Iridium 33 and Cosmos 2251 in February 2009.
“As the atmospheric density in the thermosphere decreases, debris can remain in orbit for up to 25 percent longer,” Lewis says. “The fact that these objects are staying in orbit longer counteracts the positive effects that we would otherwise see with active debris removal.”
According to Lewis, their study shows that by doubling the number of debris objects removed each year, “we can get back on track with reducing the debris population. Achieving this target, however, will be challenging,” he adds.
The research was presented here at the National Center for Atmospheric Research during the Sixth Workshop on Long-term Changes and Trends in the Atmosphere.
By LD/CSE