The European Space Agency’s annual report revealed that, although behaviour in space is improving, it’s still ‘unsustainable in the long term’. Here’s why – and how innovation can help.
Why do we need space travel?
Space missions are vitally important to our understanding of Earth. For example, satellites help forecast climate changes and monitor sea levels.
Satellites also deliver broadcasting, telecommunication and navigation services – things that are part of our everyday lives.
But with the growth of space travel – including the advent of space tourism – we have to look at how sustainable the industry is in the long term.
The bad news? As things are, it’s unsustainable. The good news? There’s a lot of new ideas and existing tech to change that.
The problem: Space junk
Space junk or debris can be anything from entire out-of-use satellites to tiny pieces of metal that have broken off rockets. Even a flake of paint could be dangerous at high speed – space shuttle windows have been damaged by paint flakes.
With more and more satellites being launched into space, there’s an increasing risk of collations and explosions. Collisions create ‘clouds’ of debris that are risks to other space objects.
The European Space Agency (ESA) estimates the current number of objects larger than 1cm is over a million.
The solution
At least 90% of all space objects must be successfully removed in order to reduce the growth rate of space debris, according to the ESA’s annual Space Environment Report. The UN requires all companies to remove their satellites within 25 years of a mission ending, though this is difficult to enforce.
Ways to remove satellites include ‘tugging’ them back into the atmosphere, where they burn up. It’s also been suggested that a certain orbit could become a ‘satellite graveyard’ where debris can float without damaging active missions – but this is a relatively short-term solution.
The ESA has partnered with Swiss startup CleanSpace for a mission to clean up ‘space lanes’ with a four-armed robot. CleanSpace-1 is planned for launch in 2025. It will be the first debris-removal space mission.
Another way to reduce debris is by servicing satellites in space – rather than decommissioning them – or repositioning them to work in a new orbit instead of sending up an additional satellite.
In the meantime, AI is being developed to help satellites carry out collision avoidance manoeuvres without a manual response being required – this will be necessary as the number of collision alerts increase.
The problem: Pollution
Space missions require a lot of fuel and use chemicals that can damage the atmosphere.
For example, rockets release chlorine and particles of black carbon (soot) and aluminium oxide that damage the ozone layer.
Traditionally, the most common rocket propellant has been hydrazine, a compound of nitrogen and hydrogen that the EU put on its list of substances of high concern. It’s been thought to cause blood and hormonal disorders in people around rocket launch sites.
Right now, the CO2 output from rockets isn’t anything on the aviation industry’s collection emissions – but as space travel becomes more common, it will be a major issue.
The solution
Greener fuel options include liquid hydrogen (ideally obtained by solar power) and oxygen, as used by NASA and Blue Origin. Hydrogen is really light, so it also reduces a rocket’s overall fuel use. It’s not perfect, though: it’s weaker than other options and the water vapour released is also a greenhouse gas.
There are other options on the table, including biofuels from agricultural waste or fuel from non-recyclable plastic waste, but these are all in the experimental stage.
Doing away with launch rockets entirely, SpinLaunch aims to use electric-powered centrifugal force, reaching several times the speed of sound, to hurl satellites into space. They claim the technology could result in a ten-time reduction of cost and a four-time reduction in fuel. SpinLaunch had its first success test launch in 2021 and its first customer launches are planned for 2025.
Scientists also continue to work on the rather old idea of a ‘space elevator’ (proposed as far back as 1895, possibly even earlier), which would send small cargo into space without a rocket, reducing costs by around 95%.
The problem: Waste
Historically, rockets have been single use. But this is unsustainable in terms of costs, materials and the energy used to create rockets and space objects. Single-use rockets and space objects also contribute to the space junk issue.
The solution
SpaceX is leading the way in reusable rocket technology. The Falcon 9 is the world’s first reusable orbital-class rocket and the aim is to reuse most of its components multiple times before they’re replaced.
Blue Origin is also prioritising the reusability of its rockets and other companies are following suit.
The problem: Onboard supplies
Water and food present further sustainability issues for space exploration companies – these items are heavy, which means the flights require more fuel. The longer the mission, the more supplies are needed.
Prepacked food nutrients break down over time, which is a problem for astronauts on long missions. The International Space Station (ISS) receives regular shipments of food – but this is costly and a further burden on Earth’s environment.
The solution
Already, the ISS recycles about 90% of its water, purifying it so it can be reused repeatedly. (We could learn a lot from some of the sustainability initiatives used in space…) They recycle everything – urine, sweat, even moisture from the astronauts’ breath!
There’s a lot of research underway to enable astronauts to produce food in space. There’s already a small veggie garden on the ISS. And NASA is working with startup Nature’s Fynd on a micro-gravity biofilm-biomat reactor to allow astronauts to grow nutritious vegan protein in space. The protein comes from Yellowstone National Park geysers – how cool is that?
Sources
Aerospace, Space Debris 101
Engineering and Technology, Modern space race needs to be built on sustainability, study says
NASA, Growing plants in space
NASA, Space Debris and Human Spacecraft
Natural History Museum, What is space junk and why is it a problem?
Science Focus, Can space exploration be environmentally friendly?
Space Australia, Renewable rocket fuels – going green and into space
The Conversation, Space tourism: rockets emit 100 times more CO₂ per passenger than flights – imagine a whole industry
The European Space Agency, Clean and eco-friendly space
The European Space Agency, ESA’s Space Environment Report 2022
