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Asked by mattiosmmm to Adam, Geoff, Rob, Sheila, Suzie on 21 Mar 2011 in Categories: Space.
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Suzie Sheehy answered on 17 Mar 2011:
When you ‘burn’ hydrogen and oxygen like in a space shuttle launch there are two products: heat and water. Neither of these things are polluting to the environment (really), but there may be some emissions from the solid fuel rockets.
I think the more important thing to think about though, are the advances in technology through space exploration (like hydrogen fuel cells etc…) that actually help us to combat pollution and environmental damage! These are by far more important than the emissions caused by the launches themselves.
Certainly an interesting thing to think about, but I think if anything, we should be doing more!!
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Adam Tuff answered on 17 Mar 2011:
This is a pretty important question actually!
Did you know there are hundreds of thousands of bits and pieces that have come off space ships floating around in orbit? It even includes a spanner that one astronaut dropped! It’s a serious problem though, because they travel at really fast speeds in orbit – even a tiny little rock could do some serious damage to space ships – we have bases on Earth that actually track where the space “rubbish” is around our planet so they don’t collide with any space ships!If too much rubbish gets into orbit, it could be very difficult to have safe space flight.
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Geoff McBride answered on 17 Mar 2011:
It’s a good point. As nations start to try and reach their targets of carbon reduction we may see some of them reducing their launch programs.
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Sheila Kanani answered on 17 Mar 2011:
Great question, ties in nicely with whether or not we should spend so much money on space, and climate change too!
Compare the cost of fuel in the USA:
Space shuttle fuel consumed in a launch: 3.5 million pounds!
Gasoline consumed in one day in the US – 2,500 million pounds!!!!!In other words, one space shuttle launch is equivalent to about two minutes of fuel consumption in the US.
The pollution caused by space launches depends also on the type of fuel used, because it isnt always fossil fuels (which is the most harmful type).
Propellants used for powering space launches are of four types:
1. Solid – Propellants that are a mixture of solid chemicals – a fuel and an oxidizer – that burn at a rapid rate when ignited, expelling hot gasses from a nozzle to achieve thrust. Fireworks are an example of the use of
this kind of propellant. The space shuttle uses potassium perchlorate (KClO4) and powdered aluminum. The combustion products are potassium chloride and aluminum oxide. Potassium chloride is used as a fertilizer and has medicinal uses. Aluminum oxide is an unreactive compound and is used as an abrasive. So not too bad.2. Cryogenic – In space propellants, this refers to liquid hydrogen (LH) and liquid oxygen (LOX), which burn when mixed and ignited. They are stored in the space vehicle in insulated tanks and pumped into the rocket engines where they burn to expel hot gases. The LOX/LH combination is by far the most efficient in the amount of thrust per pound of fuel. The combustion product is water vapor, this isn’t too harmful on the environment!
3. Petroleum – combustion products are carbon dioxide and water vapor, so this is harmful, but this fuel system is only used in launches of smaller rockets and dont happen very often.
So generally in the grand scheme of things space travel is relatively clean and not too bad for the environment. I think cars and planes are way worse at the mo!
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Robert Simpson answered on 21 Mar 2011:
We desperately need to figure out better ways of dealing with space junk. i actually wrote a blog post about this a while back: http://orbitingfrog.com/post/3424229264/space-litter
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