Why is water on the Moon such a big deal?

In October 2009, NASA performed an experiment on the Moon. This experiment involved deliberately crashing  a 2,200kg Centaur rocket stage into Cabeus, a 100km diameter crater close to the Moon's south pole. This crater was chosen because it is permanently in shadow, and this protection from the Sun's rays meant that there was a possibility of  water being stored there in the form of ice. The collision was designed to send up a plume of matter which could then be analysed by LCROSS*. At first, the success of the mission was dubious: news reports indicated a distinct lack of visible matter being thrown up. But now the results are in: There is water, in the form of ice, on the moon. And not just a little bit - the quantities inferred by the data have been described as 'significant': initial reports suggest that LCROSS spied around 100kg of water in the plume, which was kicked up from a crater no more than 30m across. The chances of the rocket hitting the largest (or only) pocket of water in the local area are very slim. This means that the probability of similar amounts of water being located in similar areas nearby are very high indeed.


What's the big deal?
There are a number of reasons why scientists, professional, amateur and aspiring, are excited by this find, and I'd like to briefly mention a few of them.

Water is the stuff of life
Water is essential for life, as we know it, to function. The presence of water (along with other substances and conditions) can give us an idea of where to look if we want to find extraterrestrial life. That's not to imply that there is life on the moon; far from it. Life is very unlikely to have acquired a foothold on the moon in any form, but confirming that water can exist in these conditions has given scientists empiracle evidence to back up theories about where deposits of water may be stored elsewhere in our solar system (and outside it).

Water is heavy
One of the biggest problems faced by space travel is that the amount of fuel needed to drive a spacecraft is very high compared to the mass you want to lift, and the more mass you want to carry, the more fuel you need. The more fuel you need, the heavier the spacecraft gets, and so on. Manned spaceflight is only made possible by paring down the things you take to the absolute essentials. One of these essentials is water. This is a problem because any volume of water is quite heavy for its size, and you need quite a lot of it to keep a crew alive. If a way were to be found of producing water after getting into space, you'd need to take less of it with you in the first place which would either lead the way for more efficient flights or free up space for equipment and other supplies. Finding water on the Moon is one step towards finding a viable extraterrestrial water source.

Moon water could pave the way for further exploration

As mentioned above, getting vehicles into space is a difficult, fuel-intensive operation. The Moon has a weaker gravitational field, meaning that launching things from the Moon would be considerably easier and more efficient than flinging them out of Earth's gravity well. One of the biggest problems with setting up such an enterprise on the Moon is keeping it supplied- we'd have to fling things out of Earth's gravity well anyway just to keep the crew of any Moon base alive. Finding a source of water on the Moon provides hope of one day being able to reach the dream of having a self-sufficient base of operations out there, from which we can launch cheaper, easier missions further out to the next stepping stone.

Linked to all three of these points, a deposit of water on the Moon could provide us an opportunity to develop and test the technologies for producing and/or synthesising essential materials and supplies, which we can then turn to uses deeper into space: mining asteroids is one example. This would introduce the possibility of self-sufficient, or at least low-maintenance, colonies further away from Earth using technology tried and tested on the Moon.




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* Lunar CRater Observation and Sensing Satellite