Curiosity to use first of nine “wet chemistry cups”


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two drill holes in clay layer
Click for full image.

The Curiosity science team has decided to use the first of its nine “wet chemistry cups” to test a recently obtained Martian drill sample for organic material.

Searching for organic molecules in rocks on Mars is no easy task. Curiosity’s Sample Analysis at Mars (SAM) instrument is designed to analyze the chemical composition of gases, which it creates by slowly heating rock samples in an oven. The volatile gases that are driven off the heated rock sample get sent to SAM’s gas chromatograph and mass spectrometer (GCMS), which can identify the different gaseous compounds. However, organic molecules are tough to detect with this technique, because instead of transforming straight into gases when heated, they can decompose into simpler molecules.

But if organic molecules are “derivatized” before they’re heated – meaning that they react with other chemicals first in order to become more volatile – then the compounds are more likely to enter the GCMS without breaking down, and SAM has a better chance of detecting them. This derivatization process uses solvents of chemicals, so we call it a “wet chemistry” experiment. Curiosity only has nine cups containing these solvents, so we are careful to save our wet chemistry experiments for only the most interesting rock samples.

The “Glen Etive” site, which we have been studying for the past month, is enticing enough for this special experiment!

They are performing this operation today. This is a big deal, because they only have nine of these cups. They have been saving them for the right time, and when the drill had problems two years ago and looked for awhile like it would never work again, they were horrified at the possibility they would never get to use them at all. While I would not be surprised if NASA issues a press release today touting this decision, do not expect any announcement of results for quite awhile, as I suspect the scientists in charge will want to publish their paper on the subject first.

This location, in the clay unit in the foothills of Mount Sharp, is a spot where they have drilled twice, as shown by the two drill holes visible near the center of the the picture above.

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