After years of work and billions of dollars, Sir Richard Branson and Jeff Bezos are preparing to climb into their own spacecrafts and take a trip to the edge of space to prove that space tourism is a viable business. Both claim green credits for their endeavours. Branson's space flight company Virgin Galactic says it has a focus on "environmental sustainability". Bezos believes space travel provides a potential solution to climate change. But the power required to fly there deserves examination.
Rocket launch emissions can include black carbon (aka soot) as well as CO2. The higher a spacecraft flies, the more fuel it requires. The Space Shuttle orbiter needed almost 720,000kg of liquid fuel and 500,000kg of solid rocket fuel to reach space.
Suborbital space flights by Virgin Galactic and Bezos' Blue Origin require less power. Blue Origin's reusable New Shepard uses a liquid hydrogen-fuelled engine to travel more than 60 miles above Earth. Hydrogen fuel does not emit carbon — though its production often does.
The VSS Unity rocket plane that Branson will travel on is air-launched and burns solid fuel for one minute to fly 50 or so miles above Earth. Virgin Galactic likens the carbon footprint for passengers to a business class return ticket on a transatlantic flight. Using data from the International Civil Aviation Organization that means about 1,238kg of CO2 per passenger.
The journey lengths are not the same, however. A return transatlantic flight covers about 6,900 miles. Virgin Galactic's trip up and down adds up to about 100 miles. Per passenger, per mile, the CO2 emissions are 12kg of CO2 for Virgin's space trip versus 0.2kg of CO2 for the commercial airline flight.
The overall CO2 footprint of space flights appears modest, mostly because rocket flights are still rare. But if space tourism takes off, expect more focus on the environmental impact of this new hobby for the wealthy.
- Lex is a premium daily commentary service from the Financial Times.
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