MAY 08, 2015

Mounting A Laser On The ISS To Clean Up An Orbital Spaceage Wasteland

WRITTEN BY: Andrew J. Dunlop
As you might have heard, along with the ISS and all of the satellites, there's also a bit of space junk orbiting the Earth, but did you know that there are and estimated 700,000 pieces of space junk, almost 3,000 tons of it? And that's not all. It's potentially hazardous to everybody and everything traveling into space. How is it hazardous, you may ask. Well, here's the thing: it's not just floating out there. Each of these thousands of pieces of space junk, ranging in size from discarded rocket stages and damaged satellites all the way down to tiny pieces of metal that are fractions of an inch in size, are in orbit, and are affected by the Earth's gravity. Consequently, most of them are traveling at about 22,000 miles per hour! For astronauts and those on the ground at mission control, these objects are potential bullets and missiles. But NASA researchers may have found a novel solution to these hazardous pieces of debris: they're planning on mounting a laser on the International Space Station to shoot them down.



Orbital debris is a problem and every launch adds to it with spent rocket stages, discarded fairings and satellites that eventually become derelict. Also, these large objects sometimes collide, turning two large hazards into sometimes hundreds or thousands of smaller hazards.

It's not that the ISS and other spacecraft are totally defenseless. They all have shielding installed on them that can withstand impacts from objects smaller than about 0.4 inches (1 centimeter), and ground-based observers can spot larger objects larger than 4 inches (10 cm) and help spacecraft avoid them. But there are vast numbers of medium sized objects which can't be safely absorbed by the ISS or other spacecraft, and they can't be spotted by ground control. Up until now there was no real defense against these mid-sized objects, but a new device scheduled to be installed on Japan's module of the space station in 2017 called the Extreme Universe Space Observatory (EUSO) could help the ISS sense these and dangerous pieces of debris. The other half of this defense system is powerful laser system NASA researchers are developing called the Coherent Amplification Network or CAN that could be used to de-orbit this potentially deadly detritus.



"The EUSO telescope, which was originally designed to detect cosmic rays, could also be put to use for this useful project," says Toshikazu Ebisuzaki, an astrophysicist and chief scientist at the RIKEN (Rikagaku Kenky?sho) Computational Astrophysics Laboratory in Wako, Japan.

You many be wondering, Won't the CAN laser just create more small pieces of debris? Well, actually, no it won't. Here's why: the CAN laser will actually heat and vaporize a very thin layer of material on the outside of each piece of debris. The vapor will act like a tiny booster causing each object to re-direct itself down into the Earth's atmosphere to burn up.

How could this system possibly deal with each of the hundreds of thousands of pieces of debris? Well the ISS-based system would be a proof of concept. The next stage of the project would be two satellites, one stationed at each of the Earth's poles, that could fire 10,000 pulses per second, each lasting one-tenth of one-billionth of a second. At this rate it wouldn't be long before the space surrounding the Earth started to get a lot cleaner.