In one of these permanently shadowed craters it’s very cold; it’s about 200 degrees below zero Centigrade. The portion of the impact that will be hot — as high as 1500 degrees Celsius initially — is primarily the rocket itself and the material that comes into immediate contact with the rocket, and that’s really a fairly small area of the overall amount of dirt that’s excavated. What does the excavation is the percussion, the sound wave, if you will, that travels through the lunar dirt, rebounds, and then lifts the dirt up, kind of like a drop of milk falling into a cup. You have this really small bead of milk, but what is lifted up is due to the percussion, or the reverberation of the sound waves that move through the milk. The same kind of thing happens on the moon. As the impact penetrates the lunar dirt, it will generate sound waves that travel through the lunar dust, they will rebound off the more dense dirt down below, and then reverberate and move back upward, lifting material with them up into the sunlight.
The material that’s lifted is not going to be perturbed very much. That’s actually one of the chief requirements that we have on this mission; the booster rocket, the one that hits first, we purge, we clean, we dry out, literally, in space for several months so that it’s very clean and pristine and free from as much contamination as possible. Then we have instruments that actually detect how much of it has either vaporized or heated so that we can understand what portion of our signal or our observations may be contaminated. That’s a consideration we’ve taken into account, but we really don’t think it’s going to amount to more than maybe five-hundredths of a percent of the total material that’s thrown up that will be altered or contaminated by the initial impact.
NTB: Why is finding some trace of water on the Moon so important to NASA?
Dr. Colaprete: It’s important for a couple of reasons. The first reason is it would be a pivotal decision point in our exploration plans. Finding water on the Moon can have great ramifications in terms of how we plan our next steps for going to the Moon and beyond. Water is a fantastic resource. It can be split to make usable oxygen, drinkable water, and probably most important, it can be used to make rocket fuel. It costs a lot of money to bring anything into space; being able to find a resource like water outside of Earth’s gravity provides the potential for mining that water, mining that resource, utilizing it, and becoming more productive on that planetary body.
The Moon is an excellent first step towards, say, Mars, or other bodies beyond in that it’s nearby. We can practice a lot of our techniques for living off the land, for In Situ Resource Utilization, and so on and so forth. Finding water on the Moon will allow us to mature our concepts of engineering and really allow us to build the confidence to live off the land and use other planetary resources.
The other side of the coin, so to speak, is the scientific value. We’re going to a place that has not seen the light of day – sunlight – for maybe 3-billion years, so they’re fantastic time capsules. Any volatiles that may have traveled to the Moon, either in the form of impacts from asteroids and comets, or even just captured solar wind particles, may migrate to these cold traps at the Poles of the Moon and be trapped there for billions of years. Understanding how this material got there and what this material – this hydrogen – is composed of, actually is understanding how our solar system, the Moon/Earth system and just the general interplanetary system itself, was formed and evolved over the last 3 or 4 billion years. So it’s like a time capsule that we can look at and study and use as a laboratory to better understand the formation of Earth.