Space Debris Talk for InspireFest2015 by Dr Lucy Rogers
(1,956 words – about 15 minutes)
Space – the final frontier. Or should that be the “terminal” frontier?
Sixty years ago, the first artificial satellite to orbit the Earth, Sputnik, was launched.
This made people worry. People in the West were worried about this superior technology that the USSR had, they worried about their futures, and they worried about nuclear war.
Nobody was worried about the rubbish they left in space by the space race. The spent rocket bodies, discarded lens caps from cameras, even dead satellites, were all just left, orbiting the Earth. Space, after all, is big. Why worry? Since Sputnik over 8,000 satellites have been launched. That’s about one every three days. Most of these provided very useful information to us here on the Earth. Most have now reached the end of their useful life some have burnt up in the Earth’s atmosphere. But a lot are still there – useless, but still in orbit.
Back in 2003 I had been out of the engineering industry for a few years, so I starting doing some voluntary work in a company that was aiming to make a manned spacecraft for the $10million X-Prize – the prize that was finally won late in 2004 by SpaceShipOne, which is now the basis for Richard Branson’s Virgin Galactic.
While working there, I learnt a lot about one small part of the rocket system, but didn’t know how all the rest fitted together. I asked for the book that explained it. I was given about 10 massive tomes, each describing one part in intricate detail. I didn’t want to have to plough through all that maths – I wanted a book that explained the basics but in Plain English. It wasn’t available. So I wrote it. Four years later, It’s ONLY Rocket Science – An Introduction in Plain English” was published. (and is available to order though all good bookshops).
While doing the research I came across the problem of space debris. All that rubbish that we had been leaving behind in space was forecast to become a huge problem
In 2011, while at Singularity University, based at the NASA Ames campus in California, I was given the opportunity to work on any project I liked, as long as it had the potential to positively affect the lives of a billion people.
I chose space debris. However, I first had to convince an astronaut who had been on four space walks that it was a problem. He didn’t believe it was. “Space is big” he said. My verbal debating skills were not very well polished at that point (it’s not something engineers often get trained in). But as he was a scientist, I knew I could sway him with facts. That evening I spent a lot of time on google. I spammed him with a very long email, complete with peer reviewed papers and publications.
The next morning he declared that space debris was a problem, and one he was worried about. I love how scientists can turn their views through 180 degrees, given new knowledge.
Since then, space debris has reached the public consciousness. Films like Gravity, with Sandra Bullock and George Clooney have helped. Although some items were not very accurate in the film – for example, an astronaut wears particularly un-sexy long johns under their spacesuit, not just their underwear.
But the threat from space debris is real - and not just from George Clooney’s body.
There are now over 21 thousand pieces of debris bigger than a melon orbiting the Earth. That’s the equivalent to one every day since Sputnik launched – three times more than the number of satellites launched. These are tracked by organisation such as NASA. You get an
email telling you to move your spacecraft if it is going to get hit by one of these out of control lumps.
But most debris is smaller and has been caused by collisions or batteries exploding. There are 500 thousand pieces between 1 and 10cm – between size of a cherry and a melon. That’s 22 new pieces every day, since the launch of Sputnik. And millions smaller than a cherry – equivalent to over 100 new pieces every day You may think that something as small as a cherry won’t cause much harm. But remember, it’s travelling at orbital velocity of 17k mph – and a cherry sized lump hitting your spacecraft at that speed, has the same effect of a hand-grenade going off.
In 1978 a scientist called Donald Kessler described a scenario that one piece of debris would collide with another, break up into thousands of smaller pieces, which in turn would crash into other debris, which would break up into thousands of smaller pieces, which in turn … This is called the Kessler effect – a self sustaining cascade that could stop us using space.
If this happened at the wrong place and time, we could be without some of our most useful satellites.
Imagine no more GPS – causing thousands of couples to start having arguments about map reading again.
But GPS is more than just maps. To work, they need very accurate clocks – accurate to one second every 13k years. This accurate clock is used for train signalling, mobile phone stations, stock markets, cashpoints and power distribution.
If the GPS satellites were taken out, we could be without power, water, and communication within half a day. Within a week there’d be no food in the shops, no banking, no satellite TV.
OK, that is a worst case scenario and the probabilities of that happening are low. But not zero.
One of my latest projects has been for Reaction Engine’s Skylon - the UK’s space plane. I have calculated the probability of a Skylon being hit by space debris, and if so, whether it is likely to cause a catastrophic failure. By looking at the different possible orbits, around the equator, over the poles, at 200km or 600km altitude, and at the design of the spacecraft and the direction in which it flies, nose first, tail first or upside down, I have worked out the safest mission profiles – and been able to highlight areas that need extra shielding.
This isn’t something that the careers advisor was able to suggest when I was at school. Technology changes quickly – look how far we have come in the last 60 years, from the launch of the first satellite to satellites being used as part of our everyday lives. We have the power to quite literally change our world, but, as Voltaire said, with great power comes great responsibility.
Yes, we have littered space with our rubbish, but fortunately it’s no longer only a few people who are worried about it. With films, news stories and even games highlighting the problem, groups around the world are considering solutions. From fishing nets to lasers, harpoons to giant scoops, creative ideas are being developed.
And these are still just a small proportion of scientists and engineers who are using their creativity to solve problems. From energy generation to water purification, food production to education, people around the world have, and still are, using science to make our lives better.
I am fortunate to have a portfolio career and can use my creativity to work not just in space, but also on fun problems. Like controlling robotic dinosaurs.
Problems are a world-wide phenomena. I have worked in places such as Nepal, China and Mallorca. And wherever I go, technology is our common language.
Humans have solved very many problems. But there are still many out there – which one will you solve?