Artwork of junk in space adapted from cover of E&T February 2018 issue

Modern space race needs to be built on sustainability, study says

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Researchers have called for a more sustainable approach to the UK’s National Space Strategy, writing in the University of Manchester's new publication, On Space, while a separate study led by UCL has warned of how climate damage caused by the growing space tourism industry needs urgent mitigation.

Based on leading research and expertise on innovative and emerging technologies, experts are calling for sustainability to be at the forefront of humanity’s next phase of space exploration. In On Space, a new publication from the University of Manchester, experts ask policymakers to consider space debris, satellite orbits and the investment needed to roll-out sustainable space technology on Earth.

Many technologies used to counter climate change, including solar panels, started out as space-age innovations. Future innovations in space technology could be used to further reduce carbon emissions here on Earth, the authors write.

Dr Aled Roberts explained that one of the biggest challenges for off-world habitat construction is the transportation of building materials, which can cost upwards of £1m per brick. A solution could be that ‘local’ resources, such as lunar or Martian soil, are used to make building materials. AstroCrete, researched at The University of Manchester, is a material made from bio-based materials and the local planetary soil to make sturdy bricks that can be used to build space habitats.

On the use of this technology on Earth, Roberts said: “Given that the construction sector accounts for 39 per cent of anthropogenic CO2 emissions, any relatively green construction material technology developed for off-world habitats could be employed as a sustainable alternative on Earth.”

Researchers also stress the need to take care of space, particularly around the Earth’s orbit. Of the 23,000 objects regularly being tracked in orbit by radar, only around 15 per cent are active satellites; the rest is space debris. As more commercial satellites are launched, such as SpaceX’s Starlink satellite cluster, the potential for space debris increases.

Dr Peter Roberts argues that one way to combat the problem of space debris is to coordinate international space policymakers to agree to prioritise the use of Very Low-Earth Orbits (VELO) for commercial operations to lessen humanity’s impact on the space environment. Higher level orbits should be reserved for science, crewed activities and space exploration.

Professor Emma Bunce, president of the Royal Astronomical Society, said: “It is exciting to contemplate the future of the UK space sector, our use of space for the good of our planet, and its robotic and human exploration more widely. The ‘space age’ is still relatively young – just 60 years – but it is clear that our future and that of our planet will be reliant on space technology and the application of space-enabled data.”

As well as sustainability, On Space advocates for the use of advanced materials, such as graphene, in UK space technology; for treating space as an environment, with a sustainable approach to space exploration; support for research and development into emerging space technologies in the UK, to further the country's net-zero ambitions; and prioritising international collaborations in UK and international space policy.

With the global space economy projected to grow from an estimated £270bn in 2019 to £490bn by 2030, this rate of growth is expected to bring with it great opportunities. Articles in On Space aim to demonstrate how pioneering research into the space sector will continue to help impact UK and international space policy through the development of home-grown space capabilities, supporting international collaborations and the levelling up of our space economy. Direct recommendations for policymakers on how issues can be best addressed are also put forward in On Space.

Meanwhile, a separate study led by UCL researchers has warned that a formidable space tourism industry may have a greater climate effect than the aviation industry and could potentially undo repairs to the protective ozone layer if left unregulated.

Published in the journal Earth’s Future, researchers from UCL, the University of Cambridge and Massachusetts Institute of Technology (MIT) used a 3D model to explore the impact of rocket launches and re-entry in 2019, alongside the impact of projected space tourism scenarios based on the recent billionaire space race.

The team found that black carbon (soot) particles emitted by rockets are almost 500 times more efficient at holding heat in the atmosphere than all other sources of soot combined (surface and aircraft), resulting in an undesirable enhanced climate effect.

Furthermore, while the study revealed that the current loss of total ozone due to rockets is small, current growth trends around space tourism indicate potential for future depletion of the upper stratospheric ozone layer in the Arctic in spring. This is because pollutants from solid-fuel rockets and re-entry heating of returning spacecraft and debris are particularly harmful to stratospheric ozone.

Study co-author Dr Eloise Marais (UCL Geography) said: “Rocket launches are routinely compared to greenhouse gas and air pollutant emissions from the aircraft industry, which we demonstrate in our work is erroneous.

“Soot particles from rocket launches have a much larger climate effect than aircraft and other Earth-bound sources, so there doesn’t need to be as many rocket launches as international flights to have a similar impact. What we really need now is a discussion among experts on the best strategy for regulating this rapidly growing industry.”

To calculate the findings, the researchers collected information on the chemicals from all 103 rocket launches in 2019 from across the world, as well as data on reusable rocket and space junk re-entry. They also used the recent demonstrations by space tourism entrepreneurs Virgin Galactic, Blue Origin and SpaceX and proposed yearly offerings of at least daily launches by Virgin Galactic to construct a scenario of a future formidable space tourism industry.

These data were then incorporated into a 3D atmospheric chemistry model to explore the impact on climate and the ozone layer.

The team showed that warming due to soot is 3.9mW m-2 from a decade of contemporary rockets, dominated by emissions from kerosene-fuelled rockets. However, this more than doubles (7.9mW m-2) after just three years of additional emissions from space tourism launches, due to the use of kerosene by SpaceX and hybrid synthetic rubber fuels by Virgin Galactic.

The researchers say this is of particular concern, as when the soot particles are directly injected into the upper atmosphere, they have a much greater effect on climate than other soot sources – with the particles 500 times more efficient at retaining heat.

The team found that, under a scenario of daily or weekly space tourism rocket launches, the impact on the stratospheric ozone layer threatens to undermine the recovery experienced after the successful implementation of the Montreal Protocol.

Adopted in 1987, the Montreal Protocol global ban on substances that deplete the ozone layer is considered one of the most successful international environmental policy interventions.

Study lead author Dr Robert Ryan (UCL Geography) said: “The only part of the atmosphere showing strong ozone recovery post-Montreal Protocol is the upper stratosphere and that is exactly where the impact of rocket emissions will hit hardest. We weren’t expecting to see ozone changes of this magnitude, threatening the progress of ozone recovery.

“There is still a lot we need to find out about the influence of rocket launch and re-entry emissions on the atmosphere – in particular, the future size of the industry and the types and by-products of new fuels like liquid methane and bio-derived fuels.

“This study allows us to enter the new era of space tourism with our eyes wide open to the potential impacts. The conversation about regulating the environmental impact of the space launch industry needs to start now so we can minimise harm to the stratospheric ozone layer and climate.”

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