Credit: Aaron Ahles, et al.

As humankind stretches out beyond Earth, a critical requirement for outposts and settlements on the Moon and Mars is the use of on-the-spot resources to create pressurized, human-rated habitats. Those distant domiciles need to be low mass (high tensile strength), must be highly reliable (high toughness) and can be easily fabricated.

The cost of hauling materials from Earth is viewed as prohibitive.

A new study suggests that Mother Nature has supplied the raw ingredients for construction purposes – in the form of an iron-nickel alloy typical of iron meteorites and M-type asteroids.

Iron-nickel (Fe–Ni) meteorites harvested on the Moon and Mars — after collection, melting and casting – can be used to create metallic sheets which can be welded into pressurized structures, at low energy and infrastructure costs.

The research into this extraterrestrial home-away-from-home idea is led by Aaron Ahles, Jonathan Emery and David Dunand of Northwestern University in Evanston, Illinois.

NASA’s Mars Exploration Rover Opportunity found an iron meteorite on Mars, the first meteorite of any type ever identified on another planet. The pitted, basketball-size object is mostly made of iron and nickel. Readings from spectrometers on the rover determined that composition
Credit: NASA/JPL/Cornell

Melting, purifying, and casting

“Extraterrestrial settlements and colonies, on planetary surfaces or in orbit, require pressurized habitats and rockets made from materials with high tensile strength (to minimize mass) and toughness (to resist fracture). Beyond early small outposts, in-situ resource utilization (ISRU) is favored, as the cost of materials transportation from Earth becomes rapidly prohibitive,” the researchers explain in their paper – “Mechanical properties of meteoritic Fe–Ni alloys for in-situ extraterrestrial structures” – appearing in a recent issue of the journal, Acta Astronautica.

They conclude that Fe–Ni meteorites can credibly be used after melting, purifying, and casting to create metal sheets that can be welded into pressurized habitats on the surfaces of the Moon and Mars or in orbit.

So far, NASA rovers have identified 15 metallic meteorites on Mars, the team notes, ranging from a few centimeters to over a meter in size, and from tens of grams to hundreds of kilograms in mass. The 12 metric ton mass of a metallic shell requires 20–30 iron-nickel meteorites, of the size/mass observed by NASA rovers on the surface of Mars, Ahles and his colleagues say.

Psyche spacecraft sidles up to M-type asteroid 16-Psyche Credit: NASA/ASU

Psyche mission

An additional impetus for the study of binary Fe–Ni alloys is the Psyche mission, soon to be launched by NASA.

That spacecraft will analyze the composition of the M-type asteroid 16-Psyche suspected to be the exposed Fe–Ni core of an early planetary body or a metal-stony asteroid whose surface is covered with metal by “ferrovolcanism” from its metallic core.

Certain weight classes loaded with nickel that are found in M-type asteroids and iron-nickel meteorites “show mechanical properties well suited for tensile load-bearing applications on Mars, on the Moon or in orbit, in particular for pressurized shells for habitats or rockets,” the researchers report.

To access the paper — “Mechanical properties of meteoritic Fe–Ni alloys for in-situ extraterrestrial structures” — go to:

https://www.sciencedirect.com/science/article/pii/S0094576521004781

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