While most PM companies are busy chasing business opportunities on earth, prospects may be slowly opening in a different sector altogether - space. Last year MIM specialists Rom and Hanh Billiet discussed the possibilities and advantages of sintering in space in a feature entitled The shape of the future? (See Metal Powder Report, September, 2003). This attracted some comment, much of it tongue in cheek.

But a recent call by the National Aeronautical and Space Administration (NASA) attracted partners for a project that in its first phase will see NASA file a notice of intent to develop a modular system to mine regolith on the Moon.

Regolith? Regolith is the name given to the layer of unconsolidated material on the surface of a planet - the loose stuff that overlies the solid rock. On Earth, soil is part of the regolith, and lunar regolith is consequently often called "soil."

As it may be. Mining regolith on the moon (above) and as we saw sintering in space last year (inset).
Illustration: Courtesy Pat Rawlings

Lunar regolith is composed in part of rock and mineral fragments that have been broken apart from underlying bedrock by the impact of meteorites. The intention is to use this material, rich in minerals, as well as hydrogen and helium from micrometeorite strikes, to manufacture structural construction elements such as slabs, blocks, beams, columns and pipes in situ.

The NASA team includes cold cement investigators from the Cold Regions Research and Engineering Laboratory (CRREL), Caterpillar for vehicles, an unnamed nuclear reactor supplier, Carnegie Mellon University for robotics, Colorado School of Mines for powder fragment and particle control, the University of California San Diego for composites, and the Center for Innovative Sintered Products (CISP) at Penn State - for sintering.

CISP is well known as a centre of excellence in the earth-bound scientific disciplines involved in powder metallurgy and ceramics, but what role is envisaged for sintering in space? NASA's idea is to build a caterpillar tractor train that includes a nuclear power source, powder scoop and particle size separation, a shaping stage, sintering stage and so on. The target is to produce simple shapes such as bricks, tubes and plates for direct use in construction on the moon.

Although early missions would be of 30 to 90 days duration to demonstrate technical feasibility, the intention is that local materials would be used to build rocket launching and landing pads, emergency shelters and, more speculatively, tubes for storing hydrogen and water. CISP's role would lie in determining the sintering cycle, furnace design, determination of shaping technologies, and testing sintered products for density, strength, permeability and other important features.

Fanciful? Well in all probability it is - at the moment. CISP's director, Professor Randall German can see one large piece of grit in the ointment in the shape of the proposal for a nuclear power source. “To my mind the demand for a nuclear power source may be the thing that stops it in its tracks," he said.

But if solar energy could be harnessed as a power source? Perhaps the safest thing would be to say: Never say never...

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