Satellite near-miss calls attention to ‘space sustainability’

31 Januari 2020

We have enough waste management problems on earth, but a near-miss incident in orbit has just brought renewed attention to the problem of satellites, “space junk” and the potential consequences of the cluttered skies.

The story started in the United States on Monday, when LeoLabs – a low earth orbit (LEO) satellite tracking service – warned that two old satellites would travel dangerously close to each other over the skies of Pittsburgh, a city of about 300,000 people in the eastern part of the country, on Wednesday night. In fact, they were expected to be no more than 15 to 30 meters apart, which is an unusually narrow window that experts described as alarming.

One of the satellites, the IRAS (13777), above, was part of the Infrared Astronomical Satellite program jointly operated by U.S. space agency NASA, the Netherlands Agency for Aerospace Programs and the United Kingdom’s Science and Engineering Research Council. Its mission was over in November 1983, but it has remained in the sky all these years.

The second satellite, the GGSE-4 (2828), has been there even longer. It was an experimental project launched by the U.S. in 1967. There is no longer any communication with either of the objects, so there is no way to control them in order to avoid a collision and, given the speeds at which they travel, an explosion into fragments far above the earth.

Fortunately that didn’t happen, nor would it have harmed anyone if it did, but a collision would have potentially created new risks for other satellites in the increasingly crowded skies. Plenty of skywatchers in Pittsburgh and beyond waited to see what would unfold, but the objects passed safely – this time – within meters of each other.

“Events like this highlight the need for responsible, timely deorbiting of satellites for space sustainability moving forward,” said LeoLabs. While “space sustainability” isn’t top of mind to the more earthbound, it’s what the scientists there do. “As the LEO ecosystem around our planet gets more congested, the risk of collisions rises, and the need to map the orbits of spacecraft, satellites and space debris grows with every launch,” they explain.

A LeoLabs visualization platform showed 14,006 objects tracked across the planet’s orbit early Wednesday morning (and it’s interactive, so users who want to check it out can search for specific countries or satellites). The company’s new space radar in New Zealand is designed to track thousands and thousands of debris objects as small as 2 centimeters.

With so much attention to the Pittsburgh near-miss, even the U.S. Space Command sent a message that the GGSE-4 and the IRAS had escaped their tragic fate. At the same time, the Department of Defense agency said it routinely tracks more than 26,000 objects in the sky, in order to protect some 2,400 active satellites.

Elon Musk’s SpaceX Starlink system, already under way, is authorized to put 12,000 satellites into orbit in order to deliver communication services across the globe, and that’s more than humanity has used since the space age began. Starlink says it wants to keep the skies clean, though, and will use a cutting-edge debris mitigation system.

“At end of life, the satellites will utilize their on-board propulsion system to deorbit over the course of a few months,” the company says. “In the unlikely event the propulsion system becomes inoperable, the satellites will burn up in earth’s atmosphere within one to five years, significantly less than the hundreds or thousands of years required at higher altitudes.”

That’s a long time. And in the meantime, all day every day, the space junk that’s already accumulated for decades will continue to spin silently above our lives.

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