Mini-Throughput: Space Junk Edition
Well, this is mildly disconcerting:
A defunct Russian satellite and a spent Chinese rocket just floating around high over Earth could smash into each other within a few days, potentially creating a big mess in orbit with potentially dire long-term consequences.
LeoLabs, which tracks space debris, put out the alert on Tuesday warning that the two large hunks of junk will come within 25 meters of each other and have up to a twenty percent chance of colliding Thursday evening.
That’s considered way too close for comfort by space standards. The two objects have a combined mass of 2,800 kilograms and if they were to smash into each other, the “conjunction” could create thousands of new pieces of space junk that would put actual functioning satellites at risk.
Space is big. Really big. You won’t believe how vastly … no, wait, that’s Douglas Adams. But space is actually big. And the orbital space above the Earth is quite large. So, although we have spent the last half century and a bit sending things up there — some estimates put as many as 20,000 artificial objects and up to 100 million pieces of debris large than a cm — collisions are thankfully rare.
But they are not unheard of. On February 10, 2009, an Iridium satellite slammed into a Russian military satellite at a combined speed of almost 12 kilometers per second. Things in orbit, by definition, have to move fast. The way orbits work is that an object moves sideways so fast that by the time it falls to the Earth, it has gone around the curve of the planet. So, it is perpetually falling toward the planet but missing. Imagine throwing a baseball harder and harder, seeing it land further and further away until, finally, you threw it so hard that by the time it came back to Earth, it had gone over the horizon and the Earth had curved away.
So, when two things hit in space, they have an enormous velocity. The sky is suddenly filled with junk. The Iridium-Kosmos collision created over a thousand pieces of debris larger than 10 cm. And every single piece of that was a danger to other spacecraft. There is a very real fear that a series of collisions could produce a chain reaction called Kessler syndrome, which would basically shut off space exploration for an indefinite period.1 And there are some big things out there. One of the most concerning things is Envisat, a giant dead environmental satellite that will not burn up in our atmosphere for another 150 years. A few years ago, the Fermi satellite had to take actions — rolling in an antenna, turning its solar panels and briefly firing its thrusters — to avoid a collision with a different Kosmos satellite.
This danger is only growing. We’ve talked about Elon Musk’s plan to orbit thousands of communications satellites and other networks have equally grandiose plans. If we don’t get a handle on what’s going on up there, Kessler Syndrome may stop being a fantasy and become a harsh grim reality.
The good news is that, like many of the disaster scenarios I talk about in this space — asteroid collisions and solar flares, for example — this is preventable. You would need an international agreement to require space debris mitigation on all launches, including the ability to deorbit any satellite that goes up. This could be as simple as requiring elliptical orbits that decay faster so the satellite re-enters earlier. There are also plans — very tentative plans — for things like tiny vehicles that would capture space debris, laser brooms that would ablate material, sending down to Earth or even “space nets”. But most of these have not gone far past the planning stage.
But we’re going to have to do something. And we’re going to have to do it internationally. The Space Age has brought us miracles from the deepest images of the universe to a phone that can tell me what room I’m in. Losing those abilities would be economically devastating. And losing a future of lunar bases, asteroid exploration and deep space missions would be a tragic cap on human ambition.