While there is water on the Moon, it’s not kept in convenient reservoirs, it’s locked away in the lunar soil. Now, a team of scientists has found that thirsty astronauts could one day refresh themselves fairly easily – by throwing a cup of Moon dirt in the microwave.
Over the past decade or so, increasing evidence has been found for water on the Moon, bound between the grains of the surface lunar dust, known as regolith. Its estimated abundance varies across the surface, with the highest concentrations at the poles where frozen deposits form in areas that never see direct sunlight.
That means future crewed missions to the Moon could pack a little lighter – but how can they wring it out into a drinkable form? A new study from scientists at The Open University and the University of Central Florida have demonstrated that a simple microwave oven can do the trick.
The team started with two different versions of simulated regolith based on the samples returned from the Apollo missions – one with the composition of the lunar highlands and another mimicking the darker soils of the mare plains. They then mixed in deionized water so that it made up between 3% and 15% of the weight of each sample, which is a conservative range estimated in previous studies.
These samples were then placed into crucibles lined with ceramic paper, and placed into a chamber that mimicked the pressure and temperature conditions of the lunar surface. This was then heated for 25 minutes with microwaves at 250 W, which is less power than the microwave oven in your kitchen.
And sure enough, the technique was able to squeeze decent amounts of water out of the samples. Over 50% of the water present in the mare-mimicking samples was extracted, and more than 67% of the highlands regolith. When heated for 35 minutes, up to 90% of the water could be extracted.
Contrary to what you might expect, however, the wettest examples fared the worst, with their extracted water dropping as low as 32%. The team hypothesized that when regolith that was more saturated was frozen, the expanding ice pushed the grains of dust farther apart, weakening the heat transfer between them and making water extraction less efficient.
The team says that low-powered microwave units could be used by astronauts to extract water from areas with relatively little water, under 10% by weight.
The research was published in the journal Acta Astronautica.