The goal is to show spacecraft in the Starlink network - what the ESA called a "mega constellation" (depicted in the animation below) that may have nearly 12,000 satellites by the late 2020s - can be directed to burn up in Earth's atmosphere. One way SpaceX is testing deorbiting is via an on-board engine called a Hall thruster, which produces highly efficient yet weak thrust by shooting out atomic ions using electricity. 44, as the satellite in question is called, descended to a similar altitude as Aeolus. The collision risk apparently came about because SpaceX is testing deorbiting a handful of its experimental satellites. So the ESA fired a thruster on its satellite to avoid any would-be strike. "It was at least clear who had to react," Krag told Forbes, adding that 1-in-1,000 odds were 10 times higher than the agency's action threshold.
Holger Krag, director of the ESA's Space Safety Program Office, told Space News that his office contacted SpaceX about the USAF alert, and that the company "acknowledged" the risk but "said that they do not plan to take action."īut Krag independently told Forbes that his office had been trying for months to contact SpaceX about the general risk of collision ever since the Starlink launch, to no avail. 'It was at least clear who had to react'Īn illustration of ADM-Aeolus, the European Space Agency's wind-monitoring satellite launched on August 22, 2018. Getting whacked by a 10-centimeter sphere of aluminum in space is like detonating 15 pounds (7 kilograms) of TNT, Jack Bacon, a senior scientist at NASA, told Wired in 2010. Such objects can travel more than 10 times as fast as a bullet and disable other spacecraft, which can create even more space junk.Įach Starlink satellite is about the size of a small work desk and weighs up to 1,100 pounds (500 kilograms), and Aeolus is about the size of a golf cart and weighs around 3,000 pounds (1,360 kilograms). One satellite smash-up can litter low-Earth orbit with thousands of sizable chunks of space debris for months, years, or even decades. Such an abundance of caution is not without warrant. Read more: A space junk disaster could cut off human access to space. While a 0.1% chance of a hit may seem low, NASA routinely moves the football-field-size International Space Station if there's only a 0.001% (1-in-100,000) chance or greater of a collision with an object. The chance of an actual strike was initially 1-in-50,000, yet those odds later worsened to 1-in-1,000. "For the first time ever, ESA has performed a 'collision avoidance manoeuvre' to protect one of its satellites from colliding with a 'mega constellation,'" the ESA tweeted, adding: "This morning, #Aeolus Earth observation satellite fired its thrusters, moving it off a collision course with a satellite in their #Starlink constellation." While satellite collision-avoidance maneuvers are rare but not uncommon, there was apparently a communications breakdown that led to the ESA tweeting the news on Monday. The collision risk involved one of SpaceX's new Starlink internet satellites, 60 of which launched on May 23, and the ESA's wind-monitoring Atmospheric Dynamics Mission Aeolus satellite, according to Jonathan O'Callaghan at Forbes. ET, according to Jeff Foust at Space News. The squadron notified both SpaceX and the ESA that their spacecraft might collide around September 2 at 7 a.m. The incident started on August 28 with an alert from the US Air Force's 18th Space Control Squadron, which keeps track of spacecraft and debris in space.
Those two realities collided about 200 miles (320 kilometers) above Earth over the weekend for SpaceX and the European Space Agency (ESA), leading to an inadvertent game of high-speed, high-stakes chicken. In space, no one can scream at you to move out of the way - and sometimes on Earth, you miss a very important email.
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