Ion Rocket to Map Moon with X-Rays

jralls writes "The Guardian is reporting that a European ion-rocket has taken the last year to reach the moon and is about to enter lunar orbit. Once it slows and gets into a very low orbit, it will probe the surface with x-rays in an effort to solve the long standing puzzle of the moon's origin."

Comments

Visibile from Earth?

[fembots]

I wonder if we are able to observe this interplanetary tortoise from earth? If it passes the bright side in full moon, we should have quite a clear view of it since it's going so slowly.

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Re:Visibile from Earth?

[pe1rxq]

That is exactly what this thing does...Use a conventional rocket to get away from earth's surface and then continue with ion propulsion to the moon.

Jeroen

Moon mining?

[FiReaNGeL]

From the article :

"The sun emits X-rays and these are reflected back into space by atoms on the Moon's surface. A magnesium atom will reflect an X-ray in a different way from an iron atom, and Grande's detector can detect these differences.

Flying over the lunar poles, so that it covers the entire Moon as it revolves below, Smart will create strip maps of the surface - and eventually a global map of its composition."

Look like useful data to me if we were in the 'mine the moon' business... maybe in a not so distant future?

Re:From the article -- galactic bowling physics?

[barakn]

Take a look at the moon. Those dark spots are the sites of enormous ancient impacts. They may have been holes briefly, but they then filled up with lakes of lava. As far as the Earth goes, the impact was so devastating that the outer layers of the Earth had to reform by falling back down.

The following contains some links to mostly non-technical explanations of planetary roundness. I'd like to point out that part of this explanation, by "Derek Sears, professor of cosmochemistry at the University of Arkansas and editor of the journal Meteoritics and Planetary Science," is wrong. He says "Planets are round because their gravitational field acts as though it originates from the center of the body and pulls everything toward it." But this is a circular argument (pardon the pun). Generally a non-spherically symmetric distribution of matter doesn't have a gravitational field that acts as if it originates from the center of the body (the "center" being the center of mass). Spherically symmetric mass distributions do have this special property, so what Sears really implied is that planets that are already round will have gravitational fields that point towards the object's center of mass. This does absolutely nothing to address cases of objects that deviate from perfect roundness, i.e. all celestial bodies. This explanation by Dr. Sten Odenwald suffers from the same argument, and there's even a hint of it here. Nonetheless, these explanations are approximately true, and require bizarre shapes to break them.

For example, imagine a homogenous, perfectly shaped doughnut (a torus with a circular cross section). At the center of the doughnut hole we'd feel no gravitational field at all (a perfectly balanced tug-of-war). But deviate from the exact center just a tiny amount, and the closer side of the doughnut becomes more attractive than the other. One suddenly experiences a gravitational field that points away from the center of mass.

The ion drive is the real story

[SimURL]

Ion drive technology allows you to explore space in ways that chemical rockets simply can't.

Quoting from the article,
"We have shown that even a small ion engine like Smart's can get us across space. Now we are planning to build space telescopes and robot probes to planets such as Mercury, using bigger and more powerful ion engines. These will take years off space-travel times. Instead of decades-long missions, we will take only a couple of years to cross space for future projects."

But,
"Ion engines need electricity and only solar panels can provide enough at present. So ion engine missions will be restricted to planets and moons near the Sun."

So the solution to deep space exploration is nuclear-powered ion-drives and NASA is working on it.