CO2 rocket could fuel return missions from Mars

Hertfordshire University is developing a carbon-dioxide-fuelled rocket that could help solve the problem of how Mars missions return to Earth.

Researchers at the university hope that by September they will have built and tested the first rocket demonstrator powered by reacting carbon dioxide with aluminium.

As Mars’s atmosphere is 95 per cent carbon dioxide, such technology could allow spacecraft visiting the planet to collect fuel for the return journey when they are there, rather than taking it with them or making it from other substances.

The rocket is the work of Ray Wilkinson at the university’s Design and Rocket Propulsion Group and MSc student Sathyakumar Sharma from Salford University.

They hope to install the carbon-dioxide engine into a launcher around 7.5in in diameter and over 6ft in length, and fly it to a height of 1,500-1,800ft.

The internally funded project will put into practice research into carbon-dioxide and aluminium-propulsion systems carried out at Purdue University in Indiana, US.

‘The problem is you’re trying to mix a controlled amount of aluminium powder into carbon-dioxide gas or liquid,’ Wilkinson told The Engineer. ‘You’ve got to compensate somehow for the acceleration or find another way of doing it.

‘In the lab you can just bolt this thing down and you can have stuff that’s as big and heavy as you like, but it all becomes much more complex when you start to actually have something that could fly.’

One idea the researchers are considering, based on recent work by US firm Space Propulsion Group, is using a binder to hold the powder together and then adding nitrous oxide to the carbon dioxide so the binder burns away and releases the aluminium particles.

Finding a fuel source that can be sourced on Mars could be vital for manned missions, which would need enough fuel to travel to the planet, land on the surface and relaunch for the return journey.

Fuel made up around 98 per cent of the weight carried by Saturn V, which launched the manned moon missions and remains the most powerful launch vehicle ever built. ‘So every tiny scrap of propellant you can save is a saving all along the line,’ said Wilkinson.

Other proposals for creating fuel on Mars include breaking down carbon dioxide from the atmosphere into oxygen, or reacting it with hydrogen to create methane.

‘But you’d need to expend a lot of energy to make this stuff and all that has got to go with you as well – you’re probably talking about taking a nuclear reactor,’ said Wilkinson.

‘Whereas, if you can use the carbon dioxide itself, all you need to do is pump it and liquidise it, and that’s very easy to do.’