“A universal definition of space sustainability is hard to find”

Have mission planners done enough to avoid creating new orbital debris? Are the components and structures reusable? What materials has the team used? Questions like these reflect growing concerns over the sustainability of space missions. A new rating system, which scores missions based on a range of markers and compliance with international guidelines, is set to provide the answers. EPFL’s Space Center (eSpace) has been given the task of finalizing and implementing it.

The system, dubbed Space Sustainability Rating (SSR), is being developed by a consortium that includes the World Economic Forum (WEF), the European Space Agency (ESA) and the Massachusetts Institute of Technology (MIT), in cooperation with BryceTech and the University of Texas. The partners spent two years working on a draft assessment framework before passing the baton to EPFL. The first sustainability certifications will be issued to mission operators in early 2022. Emmanuelle David, executive manager of eSpace, tells us more.

• Why is eSpace a good fit for this project?

The project has to do with sustainable space logistics, which is an area we’ve been researching actively at eSpace for the past three years. It’s hard to overstate the importance of sustainable thinking at a time when we’re seeing ever more traffic in orbit, a growing number of operators, the advent of satellite constellations, and private companies developing launch vehicles and other new services. So as the space industry undergoes this massive transformation, it’s our job to think critically about these changes and the technologies we need to make space missions more sustainable. As a research center with deep expertise in this field, we’re ideally placed to handle the technical aspects of the project and to liaise with industry and government. It also helps that we’re located in Switzerland, which is known for its ability to bring divergent interests together and for its tradition of neutrality.

• We’ve heard a lot about space debris in recent times. Does the rating system address this issue?

Yes, it’s central to the system. The rating covers every part of a space mission, from design to operation. And debris mitigation measures are taken into account at each step. The overall score is based on a mission’s performance across seven factors: how well the object can be identified and tracked from Earth, what measures are taken to avoid collisions, whether and how data can be shared, how well the mission adheres to international guidelines, whether information provided by the operator can be verified, and whether the object can be repaired in orbit.

• Is the idea to build a broad consensus as to what makes a space mission “sustainable”?

This is the first time we’ve tried to develop a universal definition of space sustainability. It’s really hard to find one. It isn’t easy to achieve a global consensus as to what, objectively speaking, makes a space mission sustainable or otherwise – especially when you’re dealing with both traditional space powers like Russia, the US, Europe and Asian nations, and new entrants from the private sector and elsewhere.

• The rating will take no account of the mission’s objective. How do you explain this, given how important the objective is to a mission’s environmental performance?

It’s true that, initially, the rating won’t consider the mission’s objective. This proved to be a thorny issue during early discussions among the consortium partners. More work is needed on this front. So for now, under this first version of the rating system, every mission will be treated equally – whether it’s launching a climate monitoring satellite or setting up a new satellite TV network. These aspects will almost certainly need to be built into the model in the longer term. But for the time being, the idea is to test the proposal and see how it’s received. This is just a first step.

• What practical solutions are available to space engineers to make missions more sustainable?

There are plenty of solutions out there, from debris mitigation measures to junk de-orbiting services of the kind offered by EPFL startup ClearSpace. There’s also a lot of research going on into reusing components, structures and materials. For instance, a team at EPFL’s Laboratory for Processing of Advanced Composites (LPAC) is working on a project called “Design for Demise,” developing materials that break up upon re-entry into the atmosphere. Researchers at the Laboratory of Thermomechanical Metallurgy (LMTM), meanwhile, are exploring how a future lunar base could recycle locally available rocks and minerals, for example, as part of the Additive Manufacturing In-Situ Resources Utilization (AMISRU) project; a related initiative aims to harness 3D printing techniques to use or reuse available resources. Miniaturization is another potential avenue for saving energy and resources.

• What about rocket launches? It’s easy to imagine how much fuel they need to burn to escape Earth’s gravity. How can we make that more sustainable?

There’s a lot of work happening to try to mitigate the impact of rocket launches, from designing reusable launchers that return to the ground intact to developing cleaner rocket fuels and using more sustainable materials. It’s also important to consider the overall picture – to weigh up a mission’s impact against what it brings in terms of scientific progress, how it furthers our understanding of the climate, or how it benefits society as a whole.

By requiring organizations to disclose more information about their plans and activities, this new rating system will help bring issues like these out into the open. Greater transparency is exactly what citizens want. There’s a reason why people call something they find hard to understand “rocket science.” It’s our duty to consider the social and economic impact of space missions – and to share our insights with the public.