Nasa is building robots that can dig up Martian soil and convert it into rocket fuel.
The machines will strip water from the soil and convert it into methane – a compound that has been tipped to power the rockets of the future.
They could solve a major problem facing Nasa’s deep space plans: How to keep rockets light enough to fly while still carrying enough fuel to get to and from Mars.
Nasa plans to send manned missions to Mars in the early 2030s.
But before humanity takes its first step on the red planet, the space agency will send a fleet of unmanned vehicles to test the habitability of its arid, dusty surface.
The new robots, nicknamed ‘dust-to-thrust factories’, could form part of these key early trips, according to one Nasa software engineer.
Kurt Leucht, team lead on the ambitious project, wrote about the robots in a recent article for IEEE Spectrum.
Mr Leucht’s team is building a prototype system that they dub ‘in situ resource utilisation’, or ISRU.
It works by removing water from soil and splitting it into its constituent parts, hydrogen and oxygen, though a process known as electrolysis.
It then combines the hydrogen with carbon from Mars’s atmosphere to produce methane, which has been tipped by some engineers as the rocket fuel of the future.
Methane is more stable than liquid hydrogen, today’s most common rocket fuel, and can also be stored in smaller tanks at more manageable temperatures.
Key to the fuel’s promise is that it may be recovered or created from local resources – a perk that Nasa’s ISRU robots are designed to take full advantage of.
Nasa plans to use the system for the first time ahead of its manned missions to Mars alongside robots that gather soil from the planet’s surface.
Astronauts landing on Mars in the following years will eventually use the fuel it produced to fly back to Earth.
‘This technology will one day allow humans to live and work on Mars and return to Earth to tell the story,’ Mr Leucht wrote.
Nasa faces a big hurdle in the sheer volume of conventional rocket fuel needed to reach Mars and beyond.
The agency calls this the ‘gear ratio’ problem, and robots like the IRSU could finally solve it.
‘By some estimates, to ship a single kilogram of fuel from Earth to Mars, today’s rockets need to burn 225 kilograms of fuel in transit,’ Mr Leucht wrote.
‘We’d start with 226 kg and end with 1 kg, which makes for a 226:1 gear ratio.
‘The ratio stays the same no matter what we ship. We would need 225 tons of fuel to send a ton of water, a ton of oxygen, or a ton of machinery.
‘The only way to get around that harsh arithmetic is by making our water, oxygen, and fuel on-site.’