Have you ever watched a rocket launch? A huge fireball caused by a controlled explosion pushes the rocket upwards – first slowly and then faster and faster as it accelerates the payload from 0 km/h to roughly 27.000 km/h within six to eight minutes. A spectacular show of force for a spectacular sum of money.
The number of rockets launched to orbit rises every year, from 135 successful launches in 2021 to 178 successful launches to in 2022 and already 151 successful launches in the first three quarters of 2023. Compared to the up to 40 billion airline flights worldwide per year the environmental impact of rockets launching is minimal. But nevertheless, rockets are polluters.
What rockets leave behind
Back on the launch pad a huge cloud of vapour and dust lingers for some time, consisting of water vapour, dust particles and remains of the rocket engines combustion – typically carbon dioxide (CO2) and soot. In other cases, polluting elements such as Nitric oxide (NOx) are created, a colourless gas that contributes to ozone depletion and can cause acid rain. Also, other polluting mineral-products such as Aluminium-Oxide and chlorine or sulfuric compounds are left behind in the atmosphere.
Many rockets, including the most flown rocket of the last years, SpaceX’s Falcon 9 or the Atlas V of the USA-based United Launch Alliance (ULA), fly with the dual propellants liquid oxygen (LOX) and RP-1, a highly refined version of petroleum. The combustion of these propellants leaves behind a trail of carbon soot in the atmosphere on its travel towards outer space. Cleaner rocket variants such as ULAs brand new Vulcan Centaur or the Ariane rockets used by the European Space Agency (ESA) fly with liquid hydrogen (LH2) instead of RP‑1, which by reacting with the LOX creates water vapour (H2O). Another trend for new rockets currently in development is flying on liquid methane (LCH4) and LOX which leave behind carbon dioxide and water vapour (CO2 and H2O).
Where rockets go to die
But rockets do not only leave behind gaseous pollution. Most rocket parts are single use – so what happens after they transported their payloads to outer space? Well, have you ever heard of the spacecraft cemetery (at Point Nemo)? It is an area in the South Pacific Ocean where dysfunctional space objects get ditched when no longer needed. Especially big objects such as space stations get dumped there, because they do not fully burn up when re-entering earth’s atmosphere. For example, the soviet space station Mир (Mir) was dumped there, and the International Space Station (ISS) will end up there too. And even the space objects that do burn up in the atmosphere leave behind elements such as aluminium that naturally do not occur there.
A new generation of rockets
Only a decade ago, the reuse of rocket parts was perceived a futuristic dream. Until then, the most known example of reusing a space object was the space shuttle, that got refurbished after each re-entry into earth’s atmosphere – which took many months and costed a lot of money. The first time a rocket booster – the lower part of a rocket that is built solely to transport the payload towards outer space – was reused, was the launch of SpaceX’s Falcon 9 on 30 March 2017. This was made possible by safely landing the booster safely back on earth. To this day, the Falcon rockets remain the only rocket boosters ever reused, with the record holders boosters B1058 and B1060 both being launched and landed 17 times so far. This technical revolution enables SpaceX to offer launching at a much lower price. This led to a reaction from rocket designers all over the world, eager to design the next generation of rockets at least partly reusable. This indicates a positive shift towards a more circular rocket launching economy. SpaceX is already on its way to take the next step.
A fully reusable rocket?
On 4 April 2023, a skyscraper rose to the skies above the Gulf of Mexico until exploding above the ocean after reaching a height of 39km. What some media called a major setback, better informed followers of the development saw as a further step in the testing campaign of the world's first fully reusable rocket system. The next Starship prototype is already sitting on the launch pad awaiting regulatory approval of its test flight. This about 5,000 tonnes heavy and about 120m high stainless-steel rocket is designed to be reusable without refurbishment. It is planned to return directly to its launch site where it could instantly be refuelled and launched within hours. Spaceflight would become more like airflight. The launch costs thereby drop dramatically. And so will the environmental pollution per tonne launched to orbit.
On the other hand, this will lead to more and more rockets being launched. Of course, the more rockets fly, the bigger the impact of their atmospheric pollution from fuel will get. Solutions are needed such as producing the fuel (e.g. methane) by extracting gases from the atmosphere that cause global heating (e.g. carbon-dioxide).
A circular economy in space?
But the next step of development must focus on the sustainability of satellites and space objects. Space debris and space traffic management are pressing issues that need to be dealt with sooner rather than later. This concerns the use of the limited resource of earth orbits and the crucial question of what happens to a satellite after its lifespan. Ideas range from UN Guidelines about Space Debris Mitigation, via ESAs Zero Debris Charter that is binding for all ESA-funded projects, to an international ‘orbit tax’. Moving towards a circular economy in space, ESA and its European partners in the space industry are envisioning technical solutions for sustainable operations in space, such as repairing and refuelling satellites.
In other words, …
… regulation is important but should incentivise technological advancements. The spark that led to reusable rockets was the decision of NASA to fund private companies to build rockets rather than building them itself. Creating a market for launch vehicles pushes rocket companies to lower their prices – and doing so by designing reusable, thus sustainable vehicles. The EU joined the trend recently with supporting start-ups and SMEs in the space industry through its CASSINI Space Entrepreneurship Initiative in line with its flagship programme the Green Deal.
In a circular economy, regulation must go hand in hand with setting up an environment where technological and business solutions for more sustainable products can be developed by private enterprises in a fair and productive competitive market economy.
This blog post is a part of our student blog series under the elective Sustainable Business, Finance and Circular Economy, University of Oslo.