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Andrew Alden

The First X-Ray Diffraction on Mars

By October 30, 2012

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The Curiosity rover has completed the first x-ray diffraction experiment ever done by a robot (correct me if I'm wrong), showing that a soil sample from the Rocknest locality is composed of olivine, pyroxene and feldspar—the typical mineral ingredients of basalt rock. This is not a surprise, yet that fact itself, the fact that Earthly rocks and minerals are universal, never fails to impress me.

As always, the JPL news release provides nice images, including the diffraction pattern itself, details of the equipment used in this pioneering feat, and, to my joy, a stereopair of the Rocknest site. (UPDATE: I am wrong that it's a stereopair.) That's the age-old technique behind the turn-of-the-last-century amusements that allows your brain to produce a 3-dimensional scene from two photos that are slightly offset from each other. I have a series of stereopairs with the instructions that can teach you the geologist's trick of seeing stereo without a stereoscope.


October 31, 2012 at 11:17 am
(1) Pete Quinn says:

The photo pair isn’t actually a stereo pair, just two different versions of the same image. I tried to look at them in stereo and got a “flat” image, then read the full caption more closely to confirm they are not a stereo pair.

Cool xray diffraction stuff. My undergrad 4th year project, a long time ago, was to write code that could be used to pull peaks from the trace of a Rigaku diffractometer. Fairly crude piece of code, and not remotely related to any work I’ve ever done since, but it was fun at the time as a school project.



October 31, 2012 at 1:58 pm
(2) geology guide says:

You are right. That is so weird—I certainly get a good impression of 3D when I fuse the images, but that must be a hallucination.

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