Oxygen is constantly being evacuated out of Earth’s atmosphere and into space. Thankfully, at the moment, we have enough oxygen to spare, so there is nothing to worry about. But as a result of the European Space Agency’s Cluster mission, scientists have discovered that sometime in the future, into our Sun’s old age, there might be cause to worry.
The physical mechanism ejecting our precious oxygen into space was Cluster’s mission, when it was launched in 2000. After a failed first launch, when the first lot of four satellites was lost in the first test flight of the European Ariane 5 expendable launch system, the ESA waited four years until they could send four new satellites up on Soyuz-Fregat rockets.
Flying in a tetrahedral (3-D triangle) formation, the four satellites flew at an altitude anywhere between 30,000 and 64,000 kilometers above the planet. During 2001 and 2003 the satellites were thus able to amass a large amount of information about the mechanism that sends our oxygen into space.
What they found was that the electrically charged oxygen atoms, ions, flew outwards from the poles and into space and were being slingshot out into space, gathering speed as they exited. “It is a bit like a sling-shot effect,” said Hans Nilsson, Swedish Institute of Space Physics, who headed the team of space scientists analyzing the data.
Cluster found that the slingshot behavior was caused by a change in direction of the magnetic field. Energetic particles from the solar wind can be channelled along the magnetic field lines and, when these impact the atmosphere of the Earth, they can produce aurorae. This occurs over the poles of Earth. The same interactions provide the oxygen ions with enough energy to accelerate out of the atmosphere and reach the Earth’s magnetic environment.
“Cluster allowed us to measure the gradient of the magnetic field and see how it was changing direction with time,” said Nilsson. “We are beginning to realise just how many interactions can take place between the solar wind and the atmosphere.”
Article by Josh Hill, partially adapted from ESA Press Release