Space collision avoided by only about 6 metres

An old rocket body missed colliding with a defunct satellite over Antarctica by about six meters, just days before Australia activated a new space radar that can help map the fallout from such a “catastrophic” event.

The LeoLabs West Australian Space Radar (WASR) at Collie Shire, near Bunbury in the state’s southwest, was officially switched on yesterday. It capped eight months of work assembling and calibrating the S-band active phased array radars brought in from the United States.

The incident over Antarctica is an omen of what is to come.

Similar radar arrays in New Zealand, Alaska, Texas, Costa Rica and the Azores had pinpointed the orbits of an old SL-8 rocket upper stage and the defunct Cosmos 2361 satellite and extrapolated a high probability of collision.

Leo Labs Australia Managing Director, Terry van Haren, says the new WA radar – which had just finished its calibration process – was watching for telltale signs of a collision and any resulting debris cloud.

“We were in a good position to see the first evidence of any breakup,” he told Cosmos. “We’d also have been able to speed up the tracking process from days to hours”.

The two bulky objects were projected to pass just 6m from each other. But even relatively small margins of tracking error meant that both the satellite and rocket body could be more than 10 meters out of position.

LeoLabs declared the conjunction as being very close to a “worst-case scenario”.

“Had the SL-8 rocket body and Cosmos 2361 collided, it likely would’ve resulted in thousands of new debris fragments that would have persisted for decades,” LeoLabs tweeted as the event unfolded.

The Soviet Union launched the rocket body in 1986. The Parus data relay satellite was put into orbit by the Russian Federation in 1998.

LeoLabs reports the objects are orbiting at a height of 984km. That’s what it calls a “bad neighbourhood” – a region full of derelicts and debris. 

Among them are some 160 other abandoned SL-8 rocket bodies amid a similar number of now-defunct payloads. All were deployed more than 20 years ago.

“These rocket bodies stick around for decades,” a LeoLabs report states. “In fact, the rocket body from the seventh space launch ever, Vanguard 2 in 1959, is still in LEO today… more than 64 years later.”

All are highly vulnerable to further breakup, with any fresh debris cloud potentially creating a devastating cascade of collisions. LeoLabs says there were 836 incidents where these objects passed within 100m of each other last year alone.

Previously in Cosmos: How to prevent a space collision

And the number of these discarded rocket and fuel-carrying stages, often weighing about 2000kg, keeps climbing. Another 50 or so were abandoned in 2022. 

“It’s imperative that we not only focus on collision avoidance but also debris mitigation and debris remediation to combat Space Debris. This requires investing in debris removal technologies and missions,” a spokesperson added.

That’s where WASR comes in.

Leo Labs’ van Haren says the WA facility “turns the lights on in LEO in the southern hemisphere”.

“It’s been a bit of a dark spot,” he told Cosmos Magazine. “Overall, it boosts our global network by some 20 per cent. But it is working in unison with the Kiwi space radar now to give both nations total coverage. People don’t realise how strategic these radars are.”

The WA facility’s day job, however, will be to further refine orbital tracks and pinpointing increasingly small pieces of debris. While far more lethal than a bullet, these remain largely untracked.

And a whole new space services industry is growing up around collision early warning and the provision of small, lightweight thrusters to allow valuable space assets to dodge them.

It’s not so much a “boom-bust”  industry as it is dynamic, says van Haren. “It’s congested, contested and competitive. And it’s changing every day. The great challenge is keeping up with that”.

It took the first 50 years of the Space Age to place 10,000 catalogued objects in Low Earth Orbit (LEO). Between 2007 and late 2021, that figure doubled to 20,000. And in 2022 alone a further 2500 objects were added to that tally.

“This growth shows no sign of slowing down,” the LeoLabs report states. “While exciting, we must be aware of and prepare for the challenges to come.”

Less than 30 per cent of these orbital objects are operational. And only the most recent launches carry the thrusters or equipment necessary to direct them back into the Earth’s atmosphere to burn up after their usefulness has expired.