Meet the Scientist Planning to Blast Space Junk out of Orbit With Lasers
Credit to Author: Mirjana Milovanovic| Date: Thu, 28 Mar 2019 11:55:38 +0000
Since the Soviet Union launched Sputnik into orbit in 1957, humanity has been slowly clogging our exosphere with junk. From decommissioned satellites, to fragments of destroyed rocket boosters, everything that gets discarded in orbit either falls to earth or just stays in orbit—which is why Earth is now circled by some 900,000 individual pieces of garbage. For any government or private company trying to launch stuff into space, this cloud of junk represents a costly obstruction. But for our planet’s 7.53 billion inhabitants, it represents an increasing danger.
In October last year a farmer in California found a satellite fuel tank in a circle of scorched earth near Hanford. The satellite had been in orbit since 1998, and it was assumed it would burn up on re-entry. No one was hurt when it didn’t, but two Kazakh men weren’t so lucky in 2017 when falling space junk ignited a wild fire, killing one and hospitalising the other.
Now, the cost of a full atmospheric clean up puts most governments off, but one scientist thinks he has an affordable answer. Professor Craig Smith is CEO of Electro Optic Systems (EOS), and he thinks they can build a laser powerful enough to spin space junk out of orbit.
To get a better idea of how this might work, and why we have a limited time to find a solution, we contacted Craig at his home in Melbourne.
Vice: Hi Craig, let’s start with the space junk. Can you paint a picture of the problem we’re dealing with?
Professor Craig Smith: So space junk is basically anything that’s left in space without any ability to be controlled. So defunct satellites at end of their lives become space junk if not de-orbited. Third-stage rocket bodies used to put satellites into orbit also typically remain in orbit. In the past, these boosters would have unused fuel on-board which after a few years tended to explode creating hundreds or thousands of smaller debris. In total there are now around 900,000 pieces of space junk larger than 1 cm in various orbits around the Earth. While some of the pieces are small, they’re travelling at around 30,000 kms/h, which is about eight times the speed of a high velocity bullet. So they have an enormous amount of kinetic energy, and something as small as just a few millimetres can damage or destroy a satellite.
Is anyone tracking where this stuff is?
Yeah the US Airforce tracks approximately 20,000 of the larger bits (larger than 10 cms) and publishes a catalogue that helps satellite owners avoid collisions.
And I understand there’s a theory that litter in our outer atmosphere could reach a kind of critical mass?
That’s right. The “Kessler Syndrome” was a theory first published by Kessler and Cour-Palais in 1978, and it predicted that if orbits become over-crowded with space debris, then a self-sustaining cascade of debris crashing into debris could occur making affected orbits un-useable. The problem is if this happens it would take hundreds to thousands of years for the polluted orbits to clear naturally.
How many years do we have before it becomes a problem?
In some orbits, it may already be too late to stop a Kessler Syndrome occurring. In other orbits, maybe 20-50 years depending whether we do anything about the problem. In order to reduce the amount of new debris being generated many countries now require satellites to have a de-orbit strategy at end of their satellite’s life, so it doesn’t become space junk.
On the scale of planetary disasters, how dire is this one? Like, more or less serious than climate change?
It doesn’t threaten our existence on the planet like climate change does, but it does threaten our way of life. Without really knowing it, we have become incredibly dependant on services provided by satellites. Communications, weather reports, navigation, electronic banking, agriculture—that’s just a few of the services that are facilitated by satellites in space.
Can you give me an example of a time when this ring of trash has caused an accident?
There are many cases of satellites mysteriously going off-air. The most spectacular event was when an active Iridium Communications satellite and a defunct Cosmos satellite colided in 2009. That single crash created thousands of new space debris in the 850 km band, most of which are still there today. It also didn’t help when China decided to prove to the world it had anti-satellite capabilities and fired a missile from the ground to destroy one of their own meteorological satellites. Those two events added something like 50 percent more debris to the overall problem.
Now you’re working on a way of dealing with space debris. Can you tell us about the project?
So Electro Optic Systems tracks satellites and space debris as a commercial service to governments and satellite owners. We’re now upgrading the tracking capability by increasing laser power and our ability to focus beams on smaller spots so we can deliver enough energy to perturb orbits. This work is a collaboration with other companies and universities who are part of the Cooperative Research Centre for Space Environment Management.
How did you guys come up with using lasers as the main tool for this project?
We can’t take all the credit here. Back in 2011 some guys at NASA Ames Research Centre published a theoretical paper. They concluded that if you could track an object accurately enough then you would only need a small force to change its orbit enough to avoid a collision. When we read the paper, we realised that EOS already had the accuracy tracking capability and the ability to land energy beams on small objects in space, and the ability to build big lasers. So, we put together the consortium with the necessary technologies to make a practical system that uses photon pressure from a laser beam to push an object in space.
What is the biggest challenge while planning this project?
In the end, it’s just a big engineering problem. Every part has to work together exactly as planned, or nothing works. Of course, there are technical challenges, the big laser, the adaptive optics system that focuses the laser through the atmosphere, the astrodynamics so that we can predict collisions and plan avoidance manoeuvres. We’re just solving those challenges one by one.
Why is the project running in Australia out of all places? Does it have something to do with its positioning?
Australia, with its large area, and widely distributed population is one of the most dependent countries on space services. So, we have a lot to lose. In the end, though, Australia has the most advanced technologies and facilities to undertake a massive challenge like this, and we’re up for the task.
Have you guys tested out other methods of stopping collisions in space?
EOS is a laser company, and we’ve mainly focussed on using lasers to stop collisions happening. Others around the world are looking to build satellites and developing technologies to rendezvous with a piece of space junk, capture it somehow and bring it back down to orbit.
Do you think this is a problem that will actually get solved? It seems to me humans aren’t good with future cataclysms that involve international cooperation.
Yes, it’ll get solved. Unfortunately, we will probably have to wait until the problems start impacting on our day-to-day lives. Then people will be screaming “why isn’t someone doing something about this?”. That’s when funding will start to happen and we can sort the problem out properly. And we’ll be ready. If we can make collision avoidance affordable using ground based facilities rather than expensive space based missions then we have much better prospects of avoiding the Kessler Syndrome and give nature a chance to recover.
Interview by Mirjana Milovanovic. Follow her on Instagram and Twitter
This article originally appeared on VICE ASIA.