X-ray Diffraction Used by Curiosiy

As we talk about space and the chemistry of foreign bodies millions of miles from Earth, it seems silly not to discuss one of the most important aspects regarding the analysis of such data; the retrieval of samples. Presently there are probes traveling through space gathering data and sending it back to Earth, such as the New Horizons Probe, which was launched by NASA in 2006 and is expected to pass Pluto in July 2015, as well as rovers on Mars, such as the Mars Opportunity Rover, which was launched in 2003 and has already trekked 20 miles.

Mars Opportunity Rover

Currently, there is a new rover on Mars, called the Curiosity Rover. It was this rover that created so much hype as it descended successfully onto the Martian surface on August 6th. This rover is set apart from previous rovers for its sophisticated on board sample analysis system. Through such instruments, it is possible for the rover to send important data back to Earth. One of the most important equipment on Curiosity is a spectrometer called the Chemistry and Mineralogy instrument, or Chemin for short. It is about the size of a laptop computer inside a carrying case and it measures the abundances of various minerals of Mars, which are indicative of environmental conditions that existed when they formed. 

As the gif demonstrates, Chemin performs X-ray diffraction measurements. It fires thin beams of X-rays through powdered material gathered by Curiosity. Some of the X-rays get absorbed by the atoms in the sample and then re-emitted at energies that are specifically characteristic of the particular atoms present in the sample. X-rays can also bounce away at a certain angle that corresponds to the internal crystalline structure of the sample. Measuring this angle which which the X-rays are diffracted into the detector can identify the minerals.

The image above is the X-ray diffraction results produced by Chemin which is sent back to Earth. The diffraction signals are the rings that represent the fingerprint of the minerals. The rings provides information on both what minerals are present as well as how abundant they are. 

And Chemin is only one piece of equipment on the Curiosity Rover. There are also cameras, radiation detectors, environmental sensors, and atmospheric sensors. Weighing one ton, more than any other rover made, the Curiosity Rover truly deserves the name Mars Science Laboratory.