A mighty wind satellite has been losing altitude at a steady pace of nearly one mile per day, falling towards the surface of Earth. The European Space Agency (ESA) will attempt to guide the satellite on its way down to minimize risk of damage as its pieces hit the ground.
ESA’s Aeolus satellite, named after the ruler of winds from Greek mythology, has been orbiting Earth for the past five years, measuring the planet’s winds on a global scale. Unfortunately, the satellite is nearly out of fuel and is being dragged down from its orbital altitude of 198 miles (320 kilometers) by gravity and increased atmospheric drag due to a recent surge in solar activity.
Aeolus was not designed for a controlled reentry through Earth’s atmosphere. Instead, left to its own devices, the satellite would keep losing altitude until finally burning up through Earth’s atmosphere in a few months time, with chunks of Aeolus crashing down on undesignated locations.
In order to prevent pieces of debris from potentially falling on populated areas, which would pose risk to people and property below, a team at ESA will attempt a first-of-its-kind assisted reentry. “This assisted reentry attempt goes above and beyond safety regulations for the mission, which was planned and designed in the late 1990s,” Tim Flohrer, head of ESA’s Space Debris Office, said in a statement. “Once ESA and industrial partners found that it might be possible to further reduce the already minimal risk to life or infrastructure even further, the wheels were set in motion.”
To help minimize the growing issue of defunct satellites zipping through Earth’s orbit, some satellites are equipped with controlled reentry technology that deorbits them to low altitudes so that the impact site for possible debris is within a controlled area. Although Aeolus was not built with that type of technology, ESA’s team of engineers will still try to bring it down gently.
The satellite is currently losing altitude at a rate of 0.6 miles (1 kilometer) a day. Once Aeolus reaches an altitude of 173 miles (280 kilometers), the team will send a series of commands to the satellite over a six-day period, using its remaining fuel to guide it towards an optimal position for atmospheric reentry.
The final maneuver will be conducted when the satellite is at an altitude of 93 miles (150 kilometers), directing Aeolus towards its fiery reentry through Earth’s atmosphere. The majority of the satellite will burn up on reentry, but some pieces of debris might reach Earth. The point of the assisted reentry is for those pieces to land in remote areas.
“Should all go to plan, Aeolus would be in line with current safety regulations for missions being designed today,” Flohrer said.
It’s difficult to predict exactly when Aeolus will make its way through Earth’s atmosphere; it’s currently predicted to take place end of July to beginning of August.
The satellite’s descent will accelerate over time as it comes closer to Earth and its gravitational field, in addition to the Sun possibly speeding things up even more if it emits solar flares or coronal mass ejections. Charged particles from the Sun heat Earth’s atmosphere, which prompts denser air to rise and further increases atmospheric drag on Aeolus, according to ESA.
“We are confident we can succeed with this pioneering effort that will set a new standard for space safety and sustainability now and in the future,” Tommaso Parrinello, ESA’s Aeolus mission manager, said in the statement.