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Full Transcript (below)
6. Q: How can you tell if a core sample provides evidence of life?
Stoker: "Each instrument has its own approach to looking for evidence of life. So, there's two instruments. One is called the Signs of Life Detector. And basically what this instrument is using is technologies that have come from, um, what are called DNA and protein micro array, ah, developments. And these developments have really been, um, they have come out of the biomedical industry, basically. Um, it turns out that you can grow an antibody for just about any compound – any biologically produced compound. Virtually, this is taking advantage of the immune system of biological organisms.. . . there's just a huge array of things that you can make antibodies for. So, the biomedical industry has learned how to use this to detect foreign compounds, or to detect certain, you know, potentially toxic species or whatever. And they have learned how to coat a, um, detector – essentially a light detector like a camera—like a camera chip with cells that have antibody painted on the cell so that if that cell is exposed to the compound for which the antibody is there, and then is illuminated with a laser, that cell will light up. And so you can actually make an image that shows, ah, different responses to, um-- so, basically, how our instrument works is you take a rock powder sample. You mix it up in water. And then you paint or coat, ah, an array detector that has, ah, the antibodies painted on it, and if there's any, ah, compounds in the rock that you started with that the antibodies respond to, those will light up. And so you can do this in a very generic way. Now, we are selecting – for our experiment – we are selecting antibodies to use that come from experience in searching for life in this—in the environment we're going to be testing this in in Spain. But in principle, you could use very generic compounds, um, in a very wide spectrum of things that you could search for on Mars. So, it could be anything from the basic, fundamental building blocks of life or the energy system that all life uses. Ah, or things like lipids, which are fats that all cells contain. Um, so, it's kind of a generic approach for searching for any evidence of life." (2:58 MINUTES)