Welcome to the Inquiry, I'm Charmaine Cozier, each week one question, four experts and an answer.

Three men are working in a space station around 200 miles above Earth. Suddenly they receive a warning

about a threat that could kill them. It's closing in at over 30,000 miles an hour. They have a

90 minutes before it's due. The trio move slowly and silently through a dimly lit white tunnel

using precious time to lock down metal hatches and make their way towards a hopefully more secure

location. They climb into a cold, dark, cramped, sealed capsule and wait. The threat continues towards

them. The deadly deadline arrives and passes. Then a radio message announces collision has been

avoided. It's from mission control. The American astronaut and two Russian cosmonauts onboard the

International Space Station are safe. The threat was a fragment from an old weather satellite launched

in 1979. Since that near miss in 2015, thousands more obsolete objects have been abandoned in space,

increasing the risks of working satellites being damaged or even destroyed. So this week we're asking

can we solve our space junk problem?

Part one, the satellite and the syndrome.

Were you always interested in space? Yes, as a kid. That was my main interest in

fact, I ended up building a telescope. Any chance that I would get to study anything about the

planet, so I was just extremely interested in it. My name is Don Kessler. I started the

Arbor debris program at NASA back in 1978. Don joined NASA a few years before that when natural

objects, not manufactured ones, were seen as the biggest danger to spacecraft.

He used numbers to interpret meteorite collisions and the subsequent chain of collisions,

as fragments break off and hit other fragments. Don suddenly realized the same thing could happen

with orbiting satellites, an issue that had been overlooked. A few years later he investigated

further to analyze the snowball effect of those satellite collisions over time.

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