Space Tourism’s Black Carbon Problem
The industry and the F.A.A. say the climate effects of flying civilians into space will be negligible, but some scientists fret about the accumulation of black carbon in the stratosphere. Image: MarsScientific.com and Clay Center Observatory
Virgin Galactic proudly touts the fact that each of the passengers who will fly into sub-orbital space on its SpaceShip2 will emit less carbon dioxide than a typical air passenger on a flight from New York to London. But some scientists say carbon dioxide emissions are irrelevant to measuring the greenhouse gas footprint of the nascent space tourism industry. The big threat from the scaling-up of space travel, they say, comes from something called black carbon—a type of particulate matter that, when hurled into the stratosphere, builds up for years, absorbing visible light from the sun. According to one study, black carbon emitted into the stratosphere by rockets would absorb 100,000 times as much energy as the CO2 emitted by those rockets.
"There’s one issue and it’s simple: you don’t want to put black carbon in the stratosphere. Period," says Darin Toohey, a professor of atmospheric and oceanic sciences at the University of Colorado, Boulder. Industry insiders say otherwise. Who’s right?