Explained: How space tourism will add to global warming

Billionaires Richard Branson, Jeff Bezos and Elon Musk are going all out to woo the super-rich for "paid trips to space." Virgin Galactic’s Brandon and Amazon founder Bezos, fresh from their glamorous suborbital flights, are regaling the world with their dreams and plans. They have invested billions of dollars in their startups that aspire to take space enthusiasts to the ‘edge of space’ or between 50-100 km from Earth’s surface.

The space tourism market size could be around $3 billion per annum by 2030, estimates suggest. Virgin Galactic is expecting to offer 400 space flights per year.

It all seems very exciting.

However, one needs to pause and think about the environmental impact of private space tourism.

Aircraft fuel emits a variety of chemicals into the atmosphere such as carbon dioxide, chlorine and other notorious greenhouse gases (GHGs). These adversely affect the atmosphere and damage its ability to shield harmful rays from the sun. The burning of fuels also generates additional heat and soot (black carbon) near the surface of the Earth, adding to global warming.

Private spacecraft fuel emissions could jeopardise the objective of UN's aviation agency to achieve 2 percent improvement in aviation fuel efficiency year-on-year till 2050.

Just one rocket launch carrying around four passengers (like New Shepard’s flight on July 20) emits 200-300 tonnes of carbon dioxide. Thousands of tonnes of propellants are used for spacecraft, which are built with steel, iron and aluminium (adding to GHG emissions).

Space tourism rockets emit 100 times more carbon dioxide per passenger than flights.

Researchers say emissions from spacecraft are low today (on a smaller base) but growing fast at 5.6 percent per annum.

Just 2 percent of flights contributed to 80 percent of the contrail warming effect, as per the 2020 Stettler study on Japan’s airspace.

Only a small percentage (around 5 percent) of the total fuel used in aviation could come from sustainable sources (mostly waste biofuels) even by 2030, as per the International Council on Clean Transportation (ICCT).

Despite ongoing improvements in efficiency, flying will account for 3.5 percent of global energy related CO2 emissions by 2030, up from just over 2.5 percent today.

Worldwide, flights produced 915 million tonnes of carbon dioxide in 2019, which is only 2 percent of 43 billion tonnes of CO2 produced by humans across the world, as per the industry’s own admission.

Globally, 20 percent of aviation CO2 emissions are from flights, which travel less than 1,500 km. Such flights can use sustainable fuels but the usage is very low at present. Private space travel can use sustainable fuels.

There is no practical sustainable alternative mode of fuel for 80 percent of flights that travel a distance of above 1,500 km.

Imagine how much CO2 can be produced by the high-speed space travel sector sized at even a conservative $20 billion (UBS estimates) by 2030 vis-à-vis an aviation business that is expected to post revenues of nearly $600 billion by 2021, as per the International Air Transport Association (IATA).

The aviation industry's goal is to reach net-zero carbon emissions by 2050 and halve its net emissions from 2005 levels by 2050.

Bezos’ company claims that New Shepard uses liquid hydrogen-liquid oxygen engine, which generates only water vapour as by-product.

Elon Musk’s space venture SpaceX burns kerosene for its Falcon 9 rocket while others such as the Starship use methane in. NASA’s new Space Launch System (SLS) uses liquid hydrogen.

The metals and plastic parts used in manufacturing spacecraft also add to GHG emissions. Spacecraft use steel and aluminium, and every tonne of steel and aluminium produced emits 1.9 tonnes and 11.5 tonnes of carbon dioxide, respectively.