Sometimes our priorities can get mixed up.
And with the recent rise of Sir Richard Branson's Virgin Group and Blue Origin CEO Jeff Bezos to the edge of space in weeks, questions surrounding the environmental toll of space tourism have risen to the forefront of public discourse.
However, while rocket launches are, in fact, bad for the climate, so are passenger flights. By a very wide margin.
It's true: rockets are bad for the atmosphere
Bezos has said his Blue Origin rockets are more eco-friendly than Branson's VSS Unity, the former of which consist of Blue Engine 3 (BE-3) engines, and use liquid oxygen and liquid hydrogen propellants. VSS Unity, by contrast, uses a hybrid propellant of hydroxyl-terminated polybutadiene (HTPB), a liquid oxidant, a solid carbon-based fuel, and nitrous oxide, also known as laughing gas. Less complex of a mixture is the fuel used by SpaceX: liquid kerosene and liquid oxygen. And while these propellants can all create enough force to lift payloads and humans to space, they also generate air pollutants and greenhouse gases.
While burning the BE-3 propellant produces vast amounts of water vapor, combustion of both SpaceX's Falcon rockets and Virgin Galactic's VSS Unity rockets generates CO2, along with soot and water vapor. Branson's rocket also produces nitrogen oxides, which are closely linked to air pollution in Earth's atmosphere. Roughly two-thirds of the exhaust from rocket launches is absorbed in the stratosphere, which is at 7.5 to 31 miles (12 to 50 km), in addition to the mesosphere, roughly 31 to 52 miles (50 to 85 km) high. Once there, these gases can remain for two to three years, and have multiple negative effects on the atmosphere. Some of these can convert ozone into oxygen, thinning the ozone layer which protects atmospheric life (like us) from solar radiation. And the extra water vapor functions as a surface for this ozone-converting reaction to accelerate beyond its natural pace.
Passenger flights emit far more greenhouse gases
As for CO2, we needn't say much about its effects on the atmosphere. Combined with soot or not, it can trap heat in our atmosphere, and accelerate the rate of global warming. But while these are clearly bad, and more so when compounded by the fact that Virgin Galactic aims to offer 400 spaceflights annually (to say nothing of SpaceX and Blue Origin's forthcoming tourist industries), it pales in comparison to another, more conventional form of travel and tourism: Passenger flights, which injected an estimated total of more than 900 million metric tons of carbon dioxide into the atmosphere in 2018, are a far more pressing threat to the climate.
At the time, the United Nations predicted this will triple by the year 2050, according to a New York Times report. But further research suggested that emissions from global air travel could increase 1.5 times faster than earlier estimates. This figure was the result of an analysis of 40 million flights in 2018, taken from the total passenger flights recorded globally before the coronavirus of nearly 40 million. Compared to even daily flight rates of 45,000 handled by the FAA, it's safe to say that space tourism from Virgin Galactic's meager 400 yearly space flights should not be the priority when confronting greenhouse gas emissions and climate change.