![]() ![]() To limit space debris and reduce the risk of valuable orbits becoming too cluttered to operate in, future satellites will need dedicated propulsion systems to steer them into the ocean once they have fulfilled their purpose, or be designed to burn up completely on re-entry. “We are demonstrating what additional efforts can achieve even with a space system not prepared for this,” Krag said. ![]() The process is complicated by Aeolus not being built to operate at such low altitudes. On Friday, a final burn should see the satellite fall to an altitude of 75 miles, with re-entry over the Atlantic expected about five hours later. The plan called for four more burns on Thursday aimed at slowing the satellite further and reducing its altitude to about 90 miles. The first braking manoeuvre was performed on Monday when Aeolus fired its thrusters for nearly 40 minutes, dropping its altitude to 155 miles. To steer the satellite, Esa scientists are sending carefully timed commands to the probe to first rotate it through 180 degrees and then fire its thrusters to slow it down. And while space agencies tend to allow satellites to spiral down and burn up in an uncontrolled manner once their missions are over, Esa drew up plans to use the probe’s final wisps of fuel to guide it down more safely. The spacecraft observed Earth from a low altitude of 200 miles (320km) the International Space Station is typically 50 miles higher. ![]() The probe carries a sophisticated laser instrument called a Doppler wind lidar, which has helped researchers improve weather forecasts and climate models. ![]() The Aeolus satellite launched in August 2018 and became the first spacecraft to monitor Earth’s wind currents from space. “We are reducing the risk for any chance of a fragment landing on land by a factor of three compared to the case where no action is taken – that is, compared to a natural re-entry.” “We are using the onboard propulsion system to come as close to a controlled re-entry as possible,” he added. “This is done only by rocket stages and spaceships or cargo ships so far, but not by satellites. “The spacecraft is not designed to perform a fully controlled re-entry, such as to meet a predefined small target point,” said Holger Krag, head of the space safety programme at Esa. The Aeolus satellite lifting off from French Guiana aboard a Vega rocket in 2018. ![]()
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