Two weeks ago NASA’s Curiosity Rover touched down on Mars to begin its exploration of Gale Crater. After sending back many spectacular images and receiving some major software updates, it finally got the chance to use its laser last night, with the ChemCam (Chemistry and Camera Instrument) picking the poor unfortunate rock, named ‘Coronation’ (which is most likely basalt) for target practice.
As well as simply checking the aim of the million watt laser the scientists were also analysing the material evaporated by the laser to determine if a coating of dust sat on top of the rock. Though this is the first time a rock has been analysed using a laser on another planet, it is not a new technique. Here at RSES we all seem to like shooting lasers at rocks, corals or stalagmites, as they are an important part of one of our major techniques for the analysis of trace elements. We use a technique known as Laser Ablation – Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS) to blast (ablate) holes in a sample and then suck up the ablated material, evaporate it and measure the concentrations of as many as 50 different trace elements, with concentrations ranging from the per cent (%) level down to parts per billion (ppb). Whilst I analyse mantle rocks that are broadly similar to those being analysed by Curiosity, Nick likes to zap stalagmites whilst Aimee has been known to zap her deep sea corals.
The ChemCam instrument is slightly simpler in operation than our instruments which run under a controlled atmosphere of argon, as all the analysis happens in the Martian atmosphere. It simply shoots a laser from the top of its mast to the rock (at distances up to 7 metres) and then using a telescope as part of the Light Induced Breakdown Spectrometer (LIBS) to analyse the light spectra given off by the rock. This spectra is then compared to known spectra to determine which elements are present, with Curiosity focusing on the major and minor elements that define the composition of the rock, though some trace elements may also be detected.
For more information head over to the Jet Propulsion Laboratory’s Mars Science Laboratory site, which has information on the mission targeted at all people, from kids up to scientists.