David Blake developed the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument that is currently deployed on the Mars Science Laboratory rover Curiosity. The powder-handling device inside CheMin won Blake the 2010 NASA Commercial Government Invention of the Year award. This technology allowed scientists to determine the quantitative mineralogy of the 3.5 billion-year-old rocks on the Red Planet for the first time.
NASA Tech Briefs: What can we learn from the CheMin analysis?
David Blake: If you have a mineral or an inorganic compound that’s crystalline, [CheMin] can identify that compound or mineral. Specifically, we’re looking at almost 4-billion-year-old rocks on Mars in Gale Crater. If you know all the minerals that are contained in a rock, then you know the environment in which that rock was formed. Was it mudstone formed in a lake? Was it volcanic? By doing powder X-ray diffraction on Mars, we’re able to tell you what the environment was when those rocks were laid down in sediments.
NTB: How does it work?
Blake: Conventional powder XRD requires millions of fine-grained crystals to be presented to the beam in random orientations. The powder handling device uses a relatively few coarse-grained particles (hundreds) and moves them randomly to show the appearance of a multitude of grains over time. You can think of it basically as a powered tuning fork. The little piezo driver is put between the arms of a tuning fork, and that’s just what our sample holders look like. Each arm of the tuning fork has a sample cell in it. When you vibrate the holder, which contains coarse-grained powder material, the material flows like a liquid in the cell. By doing that, we’re able to get a uniform diffraction pattern from all of the crystals that are in that cell in random orientations.
NTB: What have the results shown from samples collected on Mars?
Blake: I think the most exciting result was in a place called Yellowknife Bay. We landed and traveled about 700 meters in the wrong direction – in a direction away from where we were supposed to go because we saw something interesting. It looked like an area of bedrock. We drilled that and put the powdered material in the CheMin instrument, and sure enough, we found clays – a whole suite of minerals that basically told us that this was an ancient dry lakebed, that the water was more or less circumneutral pH; it was effectively fresh water. There were minerals in there that organisms could have used for energy. It was the first habitable environment discovered off the Earth, and the first one on Mars.
NTB: What are other possible CheMin applications on Earth?
Blake: In a portable instrument, you could go the site of a spill of an unknown hazardous powder, collect the material, and analyze it right on site. You really wouldn’t have to grind the material, and you don’t need a lot of material to do this. In the Mars cell, we have about 10 cubic millimeters of material, which is just a little pinch in the cell. Even though there are only a few hundred of these large grains in there, over time, those grains fall in front of the beam in random orientations and have the appearance of a large quantity of fine-grained powder over time.
NTB: What’s the most exciting part of your mineralogy work?
Blake: I’ve certainly enjoyed the results coming back from Mars. We’d run the instrument; a day later, the data comes back, we process it, and voila: we know all the minerals in this little powder that’s maybe 200 million miles away on the surface of Mars. Another interest is pharmaceuticals. At least half of the drugs in developing nations – drugs for tuberculosis or HIV or malaria – are counterfeit. And the standard way that you can identify counterfeits is X-ray diffraction. That’s what pharmaceutical labs do. So I’m trying to work to develop the capability to go into some of these developing nations and eliminate counterfeits.
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Join us for a live webcast and Q&A with David Blake on Tuesday, February 24, 2015, at 2:00 pm ET. Go to www.techbriefs.com/webinar263 to register for the free presentation.