Sands of Mars: digging up the red planet

The prospect of manned missions to Mars has prompted a new wave of research and speculation on the role that robotic excavators could play in the eventual colonisation of the red planet. NASA is working on automated mining technologies that could help a potential Mars colony sustain itself using local resources and has built a robotic digger prototype dubbed RASSOR, while SpaceX founder Elon Musk has discussed the need for tunnelling robots to dig out pressurised industrial spaces. How are mining technologies gearing up at the dawn of humanity’s mission to Mars?

“‘All the oxygen we need is in those ores,’ said Whittaker, kicking at the caked powder. ‘And just about every metal you can think of...’ He bent down and picked up a lump more solid than the rest. ‘I’m not much of a geologist,’ he said, ‘but look at this. Pretty, isn’t it?’"

The surface of Mars has fascinated generations of science fiction writers for decades, with the red planet offering the hope of a suitable, if hostile, extraterrestrial colony as humanity begins its long journey towards an interplanetary civilisation. And the extract above, taken from 1951’s The Sands of Mars, Arthur C. Clarke’s first science fiction novel, is a reminder that a decade before humans even achieved our first space flight, the more thoughtful of these writers were already considering how Mars’s geology might help support a human settlement.

More than 65 years on from The Sands of Mars, the prospect of a manned mission to Mars is no longer confined to the domain of speculative fiction. All of a sudden, the human race setting foot on the planet’s dusty surface has entered the realm of speculative fact.

SpaceX founder and tech impresario Elon Musk last year launched an optimistic $10bn plan to bring the first batch of ‘space tourists’ to Mars in 2024, while former US President Barack Obama in October reaffirmed the government’s aim to send humans to the planet in the 2030s. In doing so he quoted John Noble Wilford, the New York Times reporter who covered the first moon landing, who said Mars pulls at the human imagination “with a force mightier than gravity”, a statement that has never seemed truer than it does today.

But as the likes of SpaceX and NASA consider the first tentative steps towards setting up a long-term colony on Mars, what role could tapping into the red planet’s mineral resources play in making this long-held dream a reality?

Living off the land

When it comes to the long-term ambition of establishing a Martian colony, reaching the planet itself with a manned mission only scratches the surface of the challenge. A host of technologies and techniques will be needed to create a self-sustaining settlement. Given that regular trips ferrying cargo from Earth to Mars would be cost-prohibitive in almost any scenario, a colony would need to live off the land for the most part.

For years, NASA has been considering the challenges of relying on Martian resources for human survival using techniques collectively summarised as frontier in-situ resource utilisation (ISRU). These thoughts are collected in a scientific and technical information (STI) paper called ‘Frontier In-Situ Resource Utilization for Enabling Sustained Human Presence on Mars’, co-authored by Robert W. Moses and Dennis M. Bushnell of the Langley Research Center and published in April 2016.

“The ISRU technologies necessary to sustain a permanent human presence on Mars either exist now or will reach sufficient Technology Readiness Levels (TRL) in time to be implemented into the first Mars-Humans mission expected to occur by 2037,” the paper noted.

The first task would certainly be to secure water resources for essential life support. Fortunately, the surface of Mars is replete with potential water supplies, from the planet’s icy poles to “recent indications of huge ice lakes near the surface”, the STI paper notes, which could be extracted via heating using solar tents or microwave technology. The abundance of water, as well as atmospheric CO2, would make it relatively easy to chemically produce oxygen, plastics, and methane and hydrogen fuels.

Analysing the red planet’s mineral potential

But what about minerals that will be needed to fuel manufacturing efforts and build adequate subterranean habitations? The relative scarcity of data on Martian geology means there is less confidence of mineral deposits than in even the riskiest inferred mineral resources on Earth. However, there is enough information to make some likely estimations.

A 2009 research paper written by Michael D. West of the Mars Institute and Jonathan D.A. Clarke of the Australian Centre for Astrobiology contended that although the differences between the atmosphere and crusts of the Earth and Mars make mineral exploration less predictable, there are areas, especially large igneous provinces, volcanoes and impact craters that hold significant potential for nickel, copper, iron, titanium, platinum group elements and more.

"Large igneous provinces, volcanoes and impact craters hold significant potential for nickel, copper, iron, titanium, platinum group elements and more."

“Despite the large variations in topography, much localized Martian geology is flat-lying; therefore the probability of finding an ore deposit that intersects the surface will be low,” West and Clarke wrote in the study. “Crater walls, central uplifts and the edges of canyons are therefore the prime sites for mineral exploration because they expose the stratigraphy and potential mineralized zones.”

NASA has also identified that clay-like minerals are common in the planet’s surface soils, facilitating the simple production of ceramics for pottery. The most common material measure by the landers that explored Mars’s surface as part of NASA’s highly successful Viking programme in the mid-70s was silicone dioxide, the basic constituent of glass, which could be produced using time-honoured sand-melting techniques. This could facilitate the production of fibreglass, which the STI paper rated as “an excellent material for constructing various types of structure”.  

NASA’s RASSOR: automated assistance

Wherever useful minerals and other materials are to be found, it’s likely that it won’t be humans who are doing the extracting. “The crew is there to explore and to colonize, not maintain and repair,” the STI study concluded. “Any time spent on ‘living there’ and ‘housekeeping’ should be minimized to an oversight role of robotic automated tasks.”

Robots could be used for resource extraction tasks, as well as the tunnelling and construction work necessary to build out accommodation and industrial spaces. Elon Musk elaborated on these roles in an ‘Ask Me Anything’ session on popular discussion site Reddit.

“Initially, glass panes with carbon fibre frames to build geodesic domes on the surface, plus a lot of miner/tunnelling droids," Musk wrote in response to one question. “With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.”

One such robotic mining unit is under active development at NASA. The Regolith Advanced Surface Systems Operations Robot (RASSOR) was initially unveiled in 2013 and has since been developed and scaled up into a second iteration, which in recent tests proved capable of autonomously digging up soil using counter-rotating bucket drums on opposing arms. The robot is designed to achieve near-zero horizontal and very little vertical net force, allowing it to load, haul and dump space regolith in low-gravity environments while maintaining low weight and minimal complexity to make it suitable for a mission to Mars.

Powering up

Certainly RASSOR 2.0 is a good start, although it will clearly need to supplemented with other robotic units to cover the spectrum of extraction and construction tasks required for a fully functioning colony.

But how will all these robots be powered as they go about their ISRU extraction tasks, not to mention all the other power-intensive functions of a Mars colony that can produce its own fuel? NASA’s STI study makes some suggestions, with the optimal configuration deemed to be a micro-fission nuclear reactor to provide “an assured, high-capacity energy source that supplies power across the board”, while a lightweight deployable solar array could serve as a back-up if the reactor fails.

"Robots could be used for resource extraction tasks, as well as tunnelling and construction work."

The study cites the Japanese-designed RAPID-L and RAPID operator-free fast reactor concepts as a fission reactor design “of about the right size/capacity available”, while high-efficiency solar cells are sufficiently lightweight and efficient to make the journey and generate enough energy from the weaker solar rays on Mars.

Given the unpredictability of the conditions and resources on Mars, much of this planning is at this point nearly as speculative as Arthur C. Clarke’s postulations back in 1951. Musk acknowledges that it will take up to a century to create a permanent, self-sufficient human presence on the red planet, so there are many decades to work on the necessary technologies, informed by data and experience from the multiple unmanned and manned missions to Mars planned over the next 30 years. It may take a hundred years before humankind delivers on the wildest visions of its science fiction writers, but it’s heartening that so many bright minds are already hard at work to make it happen.