Rising concentrations of carbon dioxide in the Earth’s atmosphere could exacerbate efforts to clean up the increasingly scattered shell of orbiting space junk.
Greenhouse gases are a major contributor to the contraction of the upper atmosphere, according to two new studies. This contraction has been hypothesized for decades. This was the first time it was actually observed.
Some of the observed contractions are normal and revert. But scientists say the contribution from CO2 is probably permanent.
This means that some of the defunct satellites in low earth orbit and other older technology will continue to operate for longer as atmospheric drag decreases, cluttering the region and causing problems for new satellites and space observations. It means you are more likely to stay in the place.
“One result is that satellites stay up longer, which is great because people want them to stay up.” Geospace scientist Martin Mlynczak explains: of NASA’s Langley Research Center.
“But the debris also stays around longer, increasing the likelihood that satellites and other valuable space objects will need to adjust their paths to avoid collisions.”
Descriptions of the Earth’s atmosphere usually set the layers at specific altitudes, but in reality the amount of gas that surrounds our world is not static. but the largest is probably the Sun.
Well, the sun isn’t static either.get through activity cycle, from high to low and back again, approximately every 11 years. we are currently 25th such cycle It’s a cycle that started around December 2019 since the calculations began. The previous cycle, his number 24, was unusually subdued even during peak solar activity. This is how Mlynczak and his colleagues made it possible to measure atmospheric contraction.
Their attention was focused on two layers collectively known as the MLT. The lower thermosphere begins at about 90 kilometers.
NASA data time limit The satellite, an observatory that collects upper atmosphere data, provided MLT pressure and temperature information for nearly two decades, from 2002 to 2021.
In some lower layers of the atmosphere, CO2 produces a warming effect by absorbing and re-emitting infrared radiation in all directions. effectively trap some of it.
But in a much thinner MLT, some of the infrared radiation emitted by CO2 escapes into space, effectively carrying away heat and cooling the upper atmosphere. The more CO2, the cooler the atmosphere.
we already knew This cooling causes the stratosphere to contract. Now we see that it does the same to the mesosphere and the thermosphere above it. Using data from TIMED, Mlynczak and his team found that the MLT shrunk by about 1,333 meters (4,373 feet). About 342 meters of that is the result of radiative cooling by CO2.
“There is a lot of interest in seeing if we can actually observe the effects of this cooling and contraction of the atmosphere.” mrinzak says.
“We finally present those observations in this paper. We are the first to show such a contraction of the atmosphere on a global scale.”
Considering that the thermosphere spans hundreds of kilometers, 342 meters may not seem like much. however, Paper published in September Thermospheric cooling could reduce atmospheric drag by 33% by 2070, according to physicist Ingrid Knossen of the British Antarctic Survey, UK.
Atmospheric drag helps satellites and rocket stages move out of orbit after the end of a mission. Knossen found that this drag reduction could extend the orbital life of defunct space junk by 30% by 2070.
As more and more satellites are launched into low earth orbit, this will become an even bigger problem, with no real mitigation measures in sight to reduce the number of satellites or the amount of CO2.
“At all altitudes there is cooling and contraction due in part to increased carbon dioxide.” mrinzak says“As long as carbon dioxide increases at about the same rate, we can also expect these rates of temperature change to remain fairly constant at about 0.5 Kelvin. [of cooling] every ten years. “
This research Journal of Geophysical Research: Atmosphere.