This reduction in density would reduce drag on objects orbiting between 90 and 500 kilometers in the upper atmosphere, prolonging the life of space debris and increasing the likelihood of debris colliding with satellites.
If the multibillion-dollar satellites were destroyed by space debris, it could cause serious problems as society increasingly relies on satellites for their navigation systems, mobile communications and Earth monitoring functions.
The study, recently published in the journal Geophysical Research Letters, provides the first realistic projections of climate change in the upper atmosphere over the next 50 years. While some studies have looked at what will happen in the lower and middle atmospheres, much less has been done in the upper atmosphere.
One study found that as of March 2021, there were about 5,000 active and inactive satellites in low-Earth orbit (up to an altitude of 2,000 km), a 50% increase from the previous two years. Several companies plan to add thousands more over the next decade. Once decommissioned, the satellite continues in orbit, but is gradually slowed down by atmospheric drag, lowering its orbital altitude until it burns up in the lower atmosphere. Current guidelines from the Inter-Agency Space Debris Coordination Committee advise satellite operators to ensure de-orbiting of decommissioned satellites within 25 years, but the reduction in atmospheric density introduces errors in planning and calculations.
The middle and upper atmosphere has been cooling compared to the lower atmosphere. This results in a drop in density that has real implications for drag on objects at these altitudes, such as defunct satellites and debris associated with space missions. With less drag, these objects live longer, allowing objects to stay in orbit longer and at greater risk of collisions with active satellites and other space debris.
Ingrid Cnossen, a NERC independent researcher with the British Antarctic Survey, used a global model of the entire atmosphere up to an altitude of 500 kilometers to simulate changes in the upper atmosphere until 2070. She compared her projections with data from the past 50 years and found that even under modest future emissions, the predicted decline in the density of the upper atmosphere would be about twice as large as in the past 50 years.
“The changes in climate in the upper atmosphere that we’ve seen over the past 50 years and our projections for the next 50 years are a result of carbon dioxide emissions,” Cnossen said. “It’s increasingly important to understand and predict how climate change will affect these regions. , especially for the satellite industry and policymakers involved in setting standards for the industry.”
Cnossen also said: “Space debris is becoming a serious problem for satellite operators because of the risk of collisions, and the problem is being exacerbated by the long-term decline in the density of the upper atmosphere. I hope this work will help guide Appropriate actions to control the problem of space pollution and ensure that the upper atmosphere remains a viable resource in the future.”
According to the European Space Agency, there are more than 30,000 trackable debris objects larger than 10 centimeters in diameter in low Earth orbit, with 1 million debris objects larger than 1 centimeter.
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