The Earth rises over the Moon

Humans are set to return to the Moon in the coming decades, and its dust could help power the next stages of exploration. Image © Bill Anders/NASA, licensed under Public Domain via Wikimedia Commons

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Moon dust could be used to make rocket fuel

Moon dust could be the bedrock of future spaceflight.

New research has shown that Moon dust can be used to create oxygen, hydrogen and even rocket fuels which could help power human exploration to Mars and beyond. 

The future fuel for spaceflight could be right above our heads. 

Chinese scientists have shown that Moon dust could be used to make fuel for spacecraft in outer space. This has the potential to make space exploration cheaper and reduce the strain on Earth's resources, as countries and businesses around the world prepare for the next era of human spaceflight.

Professor Yingfang Yao, the study's lead author, says, 'In the near future, we will see the crewed spaceflight industry developing rapidly.

'Just like the "Age of Sail" in the 1600s, when hundreds of ships headed to the sea, we will enter an "Age of Space." But if we want to carry out large-scale exploration of the extraterrestrial world, we will need to think of ways to reduce the payload.

'This will mean relying on as few supplies from Earth as possible and using extraterrestrial resources instead.'

The findings of the study were published in the journal Joule.  

A space shuttle launches

Reusable spacecraft can help cut the resource demand of space exploration. Image © NASA, licensed under Public Domain via Wikimedia Commons

What's the problem with existing rocket fuels?

The most resource-intensive part of space travel comes in the earliest stages of the mission - getting a spacecraft off the ground. An object needs to be travelling faster than Earth's escape velocity, around 11.2 kilometres a second, to escape the pull of gravity even before air resistance is taken into account.

Achieving escape velocity requires a lot of thrust, and as a result most of the weight of a spacecraft is its fuel. For example, the Saturn V rocket, which first took humans to the Moon, weighed just under three million kilogrammes before launch, or roughly the weight of 400 elephants. 

More than 90% of this weight was fuel alone, leaving a payload of just 43,000 kilogrammes to reach the Moon's orbit.

One common rocket fuel combination, often in the upper stages, is liquid hydrogen and oxygen. As these elements are some of the most abundant in the universe, finding ways to source them in space would mean smaller amounts would need to be carried into orbit.

As the most common fuel for the first stage of a rocket is RP-1, a refined form of the fossil fuel kerosene, cutting this excess weight could slash hundreds of tonnes of carbon dioxide per launch alongside the development of reusable launch vehicles.

With the Moon set to be a hub for international space exploration in the coming decades, using its dust could be one way to make this dream a reality. 

The research team hold a sample of Moon dust used in the study

A sample of Moon dust returned by the Chang'e-5 probe was used in the study. Image © Yingfang Yao

What is Moon dust, and how can it make rocket fuel?

Moon dust is the finest portion of the rocky debris that covers the Moon's surface, which is collectively known as lunar regolith. While the regolith can be as much as 10 metres deep in places, the top few millimetres are exposed to radiation and micrometeorite strikes that break it up into a fine powder.

Unlike dust on Earth, which is made up of a mixture of soil, dead organisms and other microscopic particles, Moon dust is made up of a variety of powdered minerals and glass. In the low gravity atmosphere of the Moon, it can even pick up a static charge that throws it into the air in what is known as a dust fountain.

It was first brought back to Earth by Apollo astronauts, following which the Soviet Union sent robotic probes to recover further samples. Since then, Moon dust has been studied for a variety of purposes, including resource extraction, its health impact and its potential use as a building material.

However, many of these samples have become contaminated after reacting with Earth's atmosphere and are now less useful for studying its properties. China's Chang'e-5, mission which launched in 2020, brought the first new Moon dust samples back to Earth since 1976 and offers new opportunities to investigate it.

The group of scientists behind the latest study examined a sample of the dust, finding that it contained iron and titanium-containing substances that could be used as a catalyst to make useful materials. They demonstrated that electrodes made from the material were capable of extracting oxygen and hydrogen from water, though suffered from relatively poor stability.

The researchers also showed that Moon dust could be used to produce methane and methanol from carbon dioxide and hydrogen. Methane can be used as a rocket fuel, while methanol is the starting point in the production of a variety of useful chemicals.

While their results showed that Moon dust could be used to make useful substances for space exploration, it is not currently as efficient as existing catalysts.  

The scientists intend to test other methods to improve its catalytic ability, such as changing its structure and shape. One day, they hope to test the system in space to prove its effectiveness.

In future, they propose that Moon dust could drive a process they term 'extraterrestrial photosynthesis', in which sunlight alongside carbon dioxide and water from the breath of astronauts is used to create the resources needed to explore our Solar System.