Space-junk expert on why NASA should clean up space -- and how


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Space might seem infinite, but the area around Earth is getting seriously cluttered. This week, a report from the National Academies urged NASA to start thinking seriously about cleaning it up.

It turns out there’s a swarm of space junk swirling around our planet. Scientists are tracking roughly 22,000 pieces of satellites, rockets and other spacecraft that humans have sent into space without any plan to bring them down.


And it’s starting to get dangerous out there. A small fleck of paint that falls from a spacecraft might seem minor, but it isn’t -- especially if that fleck is moving at 10 kilometers per second.

‘At that speed, it has the kinetic energy of a hand grenade going off,’ said Donald J. Kessler, a retired senior scientist for orbital debris research at NASA. He was chairman of the National Research Council committee that wrote the report.

Kessler has been studying space debris since 1978 and is arguably one of the world’s experts on the subject. We put five questions to him about what exactly makes up space debris, who is responsible for it being up there in the first place -- and how we can get it down.

Here’s an edited transcript of the conversation.

So what is space debris anyway?

Space debris is anything that is man-made and not serving a useful function in space. The big stuff is the rocket bodies and payloads (that’s NASA talk for anything that has a function) that are no longer in orbit. The small stuff is the debris from when the big stuff explodes or collides with other big things.

Isn’t there a lot of room up in space? How likely are collisions?


Back in 1976 when I started researching space debris, there were only 3,000-4,000 objects in the catalog. Today, scientists say they are tracking 22,000 objects. What will create future debris is the rate of the collision of the objects. Back in the late ‘70s, it was predicted there would be a collision once every 75 years. Now we are saying once every five to 10 years.

Who is responsible for putting all that junk up there?

The U.S. is responsible for 30% of it. Most of the rest of it comes from the former Soviet Union. Russia and the U.S. are the two major players. But the European Space Agency is starting to move, as well as China and Japan, and even India has spacecraft in orbit. It’s getting to be a fairly international group of people.

Any thoughts on how we can clean it up?

Well, it will probably be 10 or 20 years before anything actually operational takes place. There is so much development to be done and a lot of ideas on how to do it and a lot of them are off the wall and dead on arrival. One of my favorites right now is the use of tethers — essentially, really long pieces of string that are electromagnetic and could grab objects and put them in a lower orbit so they would eventually fall down to earth.

Has NASA been ignoring the problem?


No. NASA has programs that have tried to address it, and we’ve tried to prevent the growth in orbital debris, but we’ve come to the conclusion that there is a consensus now that we are likely going to have to deal with the issue at a greater level, and that includes cleaning up space.


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