The Sustainable Space Race

20th Dec 2022
The Sustainable Space Race

Between 1955 and 1975, the US and Soviet Union battled it out in one of history’s most expensive displays of one-upmanship. When adjusted for inflation, the US alone spent a staggering $250-$300 billion on getting to the moon and the subsequent missions that followed. And that was without investing in minimising the environmental impact of those missions on our planet and the universe beyond.

Hundreds of pieces of debris from various space missions have been dumped into the pacific ocean over the years – the area has since been dubbed The Spacecraft Cemetery. But unlike the moniker may suggest, chunks of metal and plastic don’t simply die and disappear peacefully on the ocean floor. They continue to contaminate various ecosystems across the world as they slowly degrade.

The graveyard orbit

And what of the pieces that don’t make it back from space? Others are deliberately fired deeper into orbit, 22,400 miles above Earth. Here, they begin an eternal journey through the cosmos where the lack of oxygen means that they will never corrode and begin to break down.

The United States Space Surveillance Network tracks over 15,000 pieces of debris larger than 10 cm, including satellites, non-functional spacecraft and pieces abandoned during launch vehicle stages. This debris continues to orbit perilously posing a collision threat to future launches.

The need for change

Fast forward over half a century since the first moon landing, and we are slowly waking up to the realisation that we can’t continue to scatter spacecraft debris and harmful fuel across our planet and the rest of the solar system with impunity. Nor can we ignore the need to develop vital materials that can help create a more sustainable circular lifecycle. The space industry has a huge part to play in helping us all achieve net zero and other environmental goals, and the world is looking on with a critical eye.

Changes made so far

Certain progress has been made so far and this is important to point out. Investment and legislative changes have been introduced in some areas but they only tackle a tiny proportion of the problem we face.

A move away from UDMH rocket fuel

One aspect that has received some improvement in recent times is the type of fuel used to send rockets up into space.

For many years, the most common rocket propellant was unsymmetrical dimethylhydrazine (UDMH). This is a toxic compound of nitrogen and hydrogen that has been linked with many health issues. Soviet rocket scientists even gave it the nickname ‘The Devil’s Venom’. People living near or working on launch sites in Kazakhstan have experienced abnormally high levels of hormonal imbalance and blood disorders. And it’s all thought to be down to UDMH.

Space agencies around the world have vowed not to use the fuel for the early stages of a launch where it could come into contact with the Earth. It is now only used in the latter stages above the Earth’s atmosphere where it would burn up on re-entry.

Reusable rocket components

One obvious area where the space industry can and has improved its sustainability record is through reusable rocket components. Reusing rockets was one of Elon Musk’s main objectives when entering the NewSpace arena. He drew parallels between space travel and regular air travel hinting that we can reuse jumbo jets and, therefore, should be able to reuse rockets too.

Solutions to this problem have been underway for several years and true to his word, Musk has remained at the forefront of this revolutionary principle. The Falcon 9 launch system has been reusing various components since 2015 as the lower stages of the rocket are able to touch down and bring their boosters safely back to earth.

The desire to create a reusable and recyclable space industry does come at a great initial cost. However, as demand for regular space launches increases, the ability to redeploy expensive components back into orbit will end up proving to be extremely cost-effective in the long run.

Metal-hydrogen batteries

Lithium-ion batteries have become the holy grail of deep-charge mobile energy sources. But it was the space industry that recognised a much better alternative that may now also have a huge impact here on earth.

Lithium-ion batteries contain toxic materials and can pose a fire safety headache. Thermal runaway risk is the main problem whenever these batteries experience extreme temperatures. And they can spontaneously combust with devastating consequences.

Enter metal-hydrogen

Very little has been spoken about metal-hydrogen batteries in the popular media until recently. But the space industry has been harnessing its power for over 30 years. The Hubble Space Telescope, International Space Station and Mars Curiosity Rover have all taken advantage of this clever energy source.

Not only can these batteries withstand extreme climates but they also have an almost infinite life cycle. And as an added bonus, there’s no maintenance needed. For over 30 years, metal-hydrogen batteries have experienced over 30,000 charging cycles, which is 10 times more than any lithium-ion counterpart could have managed.

And it may be that us mere earthlings will soon feel the positive effects of this space-age battery composition. The idea has never been developed here on Earth due to the costs involved. But recent findings at Stanford University have shown that new materials that are in abundance on our planet could be used instead. Although they are not well suited to mobile applications at present, this new battery technology could be extremely beneficial for stationary uses and utility-scale energy storage in particular.

Carbon-fibre composite launch vehicles

Launch vehicle requirements for delivering payloads into a stable orbit are complex. There are several aspects to the procedure that need to be considered and choosing materials to match has never been a simple task. Structural material will experience extreme forces during ascent and re-entry, high temperatures during combustion and exhaust and need to be lightweight to match. These are to name but a few of the hurdles scientists face.

Traditionally, aluminium and titanium have been at the heart of launch vehicle structures. But developments in the composites industry have made it possible for companies like Rocket Lab to create launch vehicles from carbon-fibre composites that are – weight for weight – far stronger than their metal counterparts.

Not only has this allowed for reusability to become a reality but it also helps the new age of space exploration to become more sustainable. Carbon-fibre composite launch vehicles are far lighter meaning that 8-tonne payload class rockets, for example, are able to be deployed more cheaply requiring fewer launches to deliver more satellite clusters into orbit.

A challenging future for the space industry

The space industry began with a desire to explore at any cost. While the original intent may have been more political than practical, the benefits of exploring space have long since come to light. And to ensure future success in this sector, sustainability and environmental challenges are now being addressed faster than ever before.

Space junk cleanup

One of the most imminent challenges that future space travel and exploration faces is simply getting through the minefield of junk that floats around at thousands of kilometres per hour as we attempt to make it into orbit.

More than half of all satellites previously sent into orbit have now come to the end of their useful lives. And when we consider that more than 6,000 satellites are currently in orbit, that’s a lot of potential collisions waiting to happen. Even the Hubble Telescope has been the victim of a run-in with orbital trash. And it certainly won’t be the last time this happens.

No orbiting object has been successfully removed to date. And as the space industry prepares to launch many more mega-constellations into space to provide internet access for the world, more than 50,000 further satellites will be joining this perilous journey through the stars.

Heavy investment is now beginning to pour in and the UK government is also contributing to the cleanup. Debris removal tech needs to be developed as a matter of priority and some concepts are slowly coming into fruition. This is one area of sustainable space travel that will receive more than its fair share of media coverage over the coming months and years.

The search for greener fuels continues

When it comes to powering a rocket, high energy density is essential. Fuels need to provide the maximum amount of energy in the smallest space possible. And this is why chemical-based propellants have been the go-to fuel since space exploration began. For example, refined kerosene (RP-1) combined with liquid oxygen (LOX) provides a suitably dense fuel combination for a high-energy output. But it isn’t exactly an environmentally-friendly solution.

Current rocket launches collectively release around 1,000 metric tons of black carbon into the stratosphere. And this is expected to reach 10 times that amount over the next couple of decades as space activity increases. If this figure begins to climb further, then the temperature could rise in parts of the stratosphere and thin the ozone layer. In turn, this would start to change the temperature here on Earth.

There are other fuels available but the tradeoff in terms of stability and size of tanks needed don’t currently make any of them an outright contender to what we’re currently working with. It is rocket science after all and it isn’t going to be an easy mystery to solve.

ESA testing light-weight fuel tanks

Creating lightweight body structures for a launch vehicle is something that has become a reality in recent times, as we have seen. But the search for similar advancements with rocket fuel tanks is a completely different conundrum altogether. And it looked like this problem would not be solved for many years. That was until MT Aerospace in Germany joined the quest.

They set about creating a small-scale tank from carbon-fibre-reinforced plastic that was leakproof with liquid hydrogen and compatible with liquid oxygen. And all of this without the need for lining the inside with metal.

After testing several prototypes, they have made great headway. And in 2023, a full-scale demonstrator with the CFRP fuel tank installed will be tested to confirm the performance.

Tanks like these would be much lighter than regular fuel tanks and make them cheaper to manufacture. If test results are positive, it could change yet another key element of launch vehicle production to include reusable properties and make the whole process more sustainable.

Solar power stations in space

As part of the UK government’s 2050 net zero emissions goal, it is turning its attention to space to provide solutions. It may seem like an unlikely place to start, but the race is on to begin harnessing some of the resources provided by the wider universe around us and not just those here on Earth.

One such project that is being considered is a £16 billion proposal to build a solar power station in space. The concept has been proved possible on a smaller scale but now the UK wants to scale up and potentially see if it’s possible to use it as a reliable source of energy to power the nation’s needs.

The plan involves deploying a solar power satellite into orbit—this is effectively a spacecraft covered in solar panels. Electricity is generated through the panels and then sent back to Earth through high-frequency radio waves. These waves are then collected by an antenna that converts them back to electricity here on earth.

Given that the solar power station is in constant contact with the sun’s rays, there is an endless supply of energy that could be transferred back to the national grid. Recent events in the world have highlighted the need for energy security for all nations across the world. And being able to create its own abundant source of electricity would prove invaluable for the UK’s economy and its population.

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