What is Space Junk and How Does It Affect the Environment?
These rather expensive trips can concern a simple flight at the limit of space as with the Virgin Galactic’s device or a trip around the Moon as the one reserved for 2023 by the Japanese billionaire Yusaku Maezawa which will be carried out by the company SpaceX or a stay in the company of astronauts as the Russian spacecraft Soyuz proposed.
By democratizing and becoming a commodity like any other, space travel also sees its impact on the environment increase, in different ways depending on the type of flights organized. A weightlessness flight in a parabolic plane, such as the zero-G flights proposed by Novespace, are accessible for 6,000 € and have been open to the general public since 2012.
These flights have a relatively low environmental impact compared to the 4.5 billion passengers of commercial flights transported in 2019 and the 915 million tons of CO2 emitted during these trips. More expensive, in the range of $250,000, and higher, at about 100 kilometers in altitude, is the suborbital flight proposed by the Virgin Galactic company.
A report on the environmental assessment of Virgin Galactic’s SpaceShipTwo estimates that the cost of a full flight is 27.2 metric tons of CO2, or 4.5 metric tons per person for 6 passengers, the equivalent of driving around the world alone in a midsize car and twice the annual individual CO2 emission to meet the +2˚C target set to limit global warming.
SpaceShipTwo’s hybrid propulsion produces CO2 but also soot, resulting from the incomplete combustion of a nitrous oxide-based mixture. In 2010, a scientific paper estimated that 1,000 such suborbital flights would produce 600 tons of soot that would remain suspended in the stratosphere for about 10 years at an altitude of 30 to 50 kilometers and would contribute to changing the planet’s climate.
In comparison, the 7,200 tons of soot produced annually by civil aviation remain suspended at a much lower altitude and can be washed away by rain. Jeff Bezos’ company Blue Origin has also positioned itself on these suborbital journeys and proposes to transport 6 passengers along an identical trajectory.
Trips to a higher altitude to the International Space Station, once proposed by the Soyuz spacecraft, are now possible again thanks to the Crew Dragon capsule from SpaceX. These trips, organized by the company Space Adventures, will be accessible by paying about 100,000 million dollars and will be authorized after having passed aptitude tests to make sure that the body will be able to support the acceleration of the takeoff.
The Falcon rocket, which is to put the capsule into orbit, uses 119 tons of refined kerosene at liftoff, and the entire flight, including recovery of the capsule with ships and helicopter, will emit 1,150 tons of CO2, the equivalent of 638 years of CO2 emissions from a medium-sized car traveling 15,000 kilometers per year.
Thus, one space tourist is equivalent, in terms of CO2 production, to 65 passengers on a suborbital flight and about 160 years of CO2 emissions from a car. The most ambitious project, the flight around the Moon planned by the Japanese billionaire Maezawa, will be carried out with the Starship of the Super Heavy rocket developed by SpaceX and would already interest more than 2,000 candidates.
A recent environmental report indicates that the ship and rocket produce 3,750 tons of CO2 during each flight. This lunar tourism project, called DearMoon, which plans to embark 6 to 8 people, will thus produce individual CO2 emissions in the range of 470 to 625 tons.
Other environmental impacts can be taken into account, such as the impact of the facilities built to accommodate these flights. For example, for an estimated 1,000 flights per year for Virgin Galactic, it is necessary to create a launch base of 73km2 of concrete, while in comparison, the Roissy Charles de Gaulle airport in France, the largest in the European Union, occupies 32km2 for more than 470,000 aircraft takeoffs and landings per year