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Hydrogen, a strategic resource for lunar exploration

Moon

In 2016, the European Space Agency (ESA) announced its intention to establish a sustainable exploration of the Moon. Ultimately the Moon could even provide a launch pad for missions to Mars! In preparation for future trips, the ESA has already started building a replica of this base, called Luna, which it will install at the European Astronaut Center in Cologne, Germany. Its director, Frank De Winne, also an astronaut with the European Space Agency, shares his insight on the challenges underlying this extraordinary project. In addition, he spoke with us about the latest research and the solutions in development to ensure that astronauts can live on the Moon. He also touched on the broader role hydrogen can play in preparing for sustainable exploration of the Moon.

Everyone with an interest in space exploration knows how crucial it is to find systems that allow astronauts to work in a livable environment. Does hydrogen already figure among the resources employed for this purpose?

Frank De Winne near a window in the Japanese Kibo laboratory
Frank De Winne near a window in the Japanese Kibo laboratory (Copyright: NASA)

Hydrogen is still used only rarely on board the International Space Station. Electrolysis is used primarily to produce oxygen from water, even though research is underway to utilize the hydrogen produced during this same chemical reaction. Among its potential applications, the gas can notably help to eliminate the CO₂ emitted by the crew through the Sabatier reaction. One such system is already being tested on the International Space Station: it makes it possible to produce oxygen and methane — ejected into space — by reacting the carbon dioxide present in air and hydrogen obtained through electrolysis. With this solution, the hydrogen that was once ejected into space becomes a crucial element for maintaining the atmosphere and ensuring the survival of astronauts. It’s also a pathway we are exploring for the lunar project.

What are the goals of this project you are working on at the European Space Agency?

The project aims primarily to enable sustainable exploration of the Moon. The first step will be to secure access to the lunar surface with reusable equipment. To that end, and together with our partners on the International Space Station, we are developing the Lunar Orbital Platform-Gateway, a new station that will serve as an outpost for missions to explore the Moon and the rest of our solar system. By 2025, it should be ready to welcome its first crew, while awaiting the completion of an in-situ lunar base that will accommodate astronauts by 2030.

ESA’s European Astronaut Centre in Cologne, Germany
ESA’s European Astronaut Centre (EAC) in Cologne, Germany, trains and prepares astronauts for their missions into space. (Credits: ESA)

The base is still a long way from operational, but its operation is already raising many important questions, notably concerning the life support and energy management systems. In response, the ESA began developing Luna, a 1,000m² replica installed at the European Astronaut Center in Cologne, Germany. Luna has two goals: enabling astronauts to train and test the tools and technologies developed by a wide ecosystem of scientific and industrial partners within an environment analogous to the Moon. Construction of this structure should get underway in 2020, with the first industrial trials expected in 2021. It will include a habitation module and will be fueled by a highly complex energy management system that we are now developing with Air Liquide.

What will the habitation module look like?

Like a pressurized container of about 40m³ that can maintain a crew of up to four people with life support systems that we will develop on Earth. The module will also have several access doors, so that we can expand it to suit our needs by adding other containers. Such a container could for example be a food production container funded by the European Commission and another containing an isolated life support system. At the same time, we are also studying a concept for an inhabitable vehicle that would allow astronauts to explore the Moon autonomously for 15–30 days.

Multi-dome lunar base being constructed, based on the 3D printing concept
Multi-dome lunar base being constructed, based on the 3D printing concept. Once assembled, the inflated domes are covered with a layer of 3D-printed lunar regolith by robots to help protect the occupants against space radiation and micrometeoroids. (Credits: ESA/Foster + Partners)

We considered several scenarios for powering the vehicle, amongst other a hydrogen system. In fact, this system is longer-lasting and more viable than electric or solar batteries, which are much less efficient after a certain usage time. To develop these space systems, we receive support from industrial and scientific partners that have a technological motivation to take part in the project. The research we are conducting with Air Liquide is revealing hydrogen’s full potential for applications on the Moon, as well as on Earth. In this way, space exploration is a wonderful testing ground.

Are there any other hydrogen applications being explored in connection with the project?

A large portion of our research focuses on developing an energy system capable of powering a lunar base on a long-term basis. Considering that a single day and night on the Moon lasts 28 Earth days, the main challenge is energy storage. We have already ruled out the idea of using electric batteries. Not only are they too heavy to transport, but their efficiency is limited over time. On the other hand, fuel cells offer a much longer life and are also lighter, but they require both hydrogen and oxygen for their operation. However, these two resources can be produced on site, via electrolysis, using the water available on the lunar surface. In theory, it should be possible to produce hydrogen on the Moon in order to store the energy needed to power the future base. One option that will be examined in the years ahead is an all-hydrogen solution to power applications like mobility, heating and energy distribution on the Moon.

Is the idea to have a self-sufficient lunar base by relying as much as possible on resources available on site?

It is. The only way to pursue sustainable exploration of the Moon is by using the resources available locally to power the life support systems, produce oxygen or store energy. But that also raises several complex issues. For starters, we do not currently possess a precise cartography of available resources, nor the proper technology for exploiting these resources. Returning to the example of water, this resource is only located on certain parts of the Moon and contains numerous impurities. Electrolysis, however, is a process requiring water that is completely pure. At the European Space Agency, we are leading fundamental research to develop concepts that may work in these conditions. Sending robots to collect samples from the lunar surface in the first half of the 2020s will help us conduct this prospective work. But the actual development and in-situ testing of these systems is not part of our duties at EAC. Our role is above all to prepare the way and propose several viable avenues for the lunar project to one day become a reality!

Frank De Winne prepares for release of he Japanese H-II Transfer Vehicle
Frank De Winne prepares for release of he Japanese H-II Transfer Vehicle (Copyright: NASA)

Does the lunar exploration project take ecological considerations into account?

Absolutely. Pollution management is one of the major challenges we consider when researching, validating and selecting the systems we intend to roll out on the Moon. Humans have polluted the Earth enough to know that we do not need to carry this plague to other areas of our solar system. We are considering many potential solutions to ensure sustainable exploration of the Moon. We know that if we use batteries, we will eventually need to replace them, and they cannot be recycled. For that reason, we are better off focusing on permanent and reusable systems like fuel cells. Creating waste is inevitable, but we can do our best to keep our waste to a minimum. To that end, hydrogen is one of the most promising solutions for reaching this goal, both on the Moon and on Earth.

Apart from these advanced technical uses, what role do you think hydrogen can play in the energy transition?

The research we are conducting for the lunar project is also helping us make progress on ecological issues. In my opinion, hydrogen is an energy vector that offers the dual advantage of being both clean and abundantly available on our planet. I think the main obstacle to its development pertains more to logistics and storage than safety. Consider the example of mobility: technologies exist already and work rather well… So why aren’t there more hydrogen cars in the world? We cannot reasonably expect all our cars to run on electric batteries in the future. It’s impossible because we simply do not have the resources to produce so many batteries on Earth. Personally, I’m convinced that hydrogen is part of the solution and has a role to play in creating a safer, cleaner world.