Are rocket launches bad for the environment?

In theory, yes. There are various ways a rocket launch can cause environmental damage, but in practice, they make a very minor contribution to such damage compared to things we do in our everyday lives. Any rocket engine is powered by a chemical reaction of some sort, which may produce some polluting gases (although the most efficient reaction of all, combustion of liquid hydrogen and liquid oxygen to make steam, is also the ‘cleanest’ in environmental terms). Gases left behind as the rocket blasts through the atmosphere make no substantial contribution to the greenhouse effect compared to cars and ground-based industry. Although these exhaust gases can damage the protective ozone layer about 20 kilometres (12.4 miles) up, recent research suggests they are only responsible for about one per cent of human-inflicted damage at most. All in all, the harm caused is insignificant compared to how much satellites and space experiments have taught us about the environment and how we can better take care of it.

Answered by Giles Sparrow