A series of geomagnetic storms in 2023 pumped terawatts of energy into Earth’s upper atmosphere, helping raise its temperature and altitude to a 20-year high. This is worrisome because the number of active satellites on Earth has tripled since SpaceX began launching Starlinks in 2019. The growing constellation of 4,100 Starlinks now provides Internet services to more than a million customers.
What is the thermosphere and why does it get hot?
The thermosphere is the uppermost layer of the Earth’s atmosphere, which starts at about 80 km altitude and continues up to about 600 km altitude. It is extremely sensitive to solar activity, easily absorbing the energy of solar flares and geomagnetic storms. Solar activity heats the upper part of the atmosphere, and the additional heat does not affect the weather or climate on the Earth’s surface, but it is important for satellites in low Earth orbit.
NASA’s Daily Thermospheric Climate Index tracks heat energy in Earth’s upper atmosphere. So far, solar cycle 25 is well ahead of solar cycle 24.
What problems might this cause for satellites?
The thermosphere, heated by geomagnetic storms, is now touching satellites in Earth orbit and pulling them down. This could shift the satellites’ positions by many tens of kilometers, increasing the risk of collisions and forcing some of the lowest satellites out of orbit. A growing constellation of 4,100 Starlinks now provides Internet services to more than a million-plus customers, and an extreme geomagnetic storm like the Halloween storms of 2003 could cause serious problems.
What data is there about the heating of the thermosphere?
NASA Langley’s Martin Mlynczak has been using the SABRE instrument on NASA’s TIMED satellite for 20 years to monitor infrared radiation from the “thermosphere,” the atmosphere’s uppermost layer. He says we are now seeing some of the highest readings in the 21.5-year history of the mission. In calendar year 2023, there were five significant geomagnetic storms that led to a marked increase in the amount of infrared radiation (heat) in the Earth’s thermosphere.
What consequences might the continued warming of the thermosphere have?
If current trends continue, the thermosphere will warm even more in 2023 and 2024. This could cause serious problems for satellites in low Earth orbit, especially the constellation of 4,100 Starlinks.
