Countdown to Curiosity: 7 days to go

Yesterday we talked about the cameras on Curiosity – and there’s plenty of them. Curiosity is going to document Mars in high resolution and send back some pretty amazing HD movies.

Today we’ll talk about another set of sensors (slightly confusingly also called a camera) namely, ChemCam. The “Chem” part is a dead give away, this package is designed for determining what elements are present on Mars. ChemCam contains two major instruments:

LIBS, short for laser-induced breakdown spectroscopy, will do what every science fiction buff wants to do – vapourize things with a laser. Yup, this is the first interplanetary mission with a laser! But before everyone gets too excited, LIBS will only focus its laser (on Curiosity’s mast) into a point 0.3 to 0.6mm in diameter. Although it will achieve a really high energy density within that spot, 10 MegaWatts per mm squared. Physics note: remember this is a power rating though, how much energy is expended per second. In fact the laser will typically only fire for 5 nano seconds so the total energy focused on the spot turns out to pretty small, about 14 milli Joules of energy (that’s about as much energy as it takes to pick up a pencil and get ready to write with it).

But once the laser has vapourized the small amount of material (and it can choose spots up to 7m away) the light from that event will be captured and analyzed using a spectrometer. By looking for different wavelengths of light associated with different atoms it will then be possible to determine precisely what elements were in the vapourized sample. We can expect to find Na, Mg, Al, Si, Ca, K, Ti, Mn, Fe, H, C, O, Li, Sr, Ba, S, N, P, Be, Ni, Zr, Zn, Cu, Rb, and Cs (at least these are all found in rocks on Earth). From the data collected by LIBS we’ll start to understand Mars geology far better than we do right now (both at local and regional levels) and we’ll also learn more about trapped water in rocks and minerals on Mars. Oh and whether there are any materials that are potentially hazardous.

RMI, the Remote Micro-Imager, provides imaging of the spots that LIBS vapourizes. It will help provide a geological context for the data that LIBS gathers – did we vapourize the rock, or something that was actually sitting on top of it? This isn’t as simple as it sounds because rocks often have layers of dust on top of them and RMI will help determine when that dust has been removed (it might need a number of shots from the laser). RMI will also be able image farther out than the 7m limit of LIBS and will be able to resolve features 1mm in diameter at 10m away (see picture at right for an example from laboratory testing).

So that’s ChemCam! A suite of tools to let us determine what Martian rocks are made of (and it can do it remotely, no need to pick up samples or anything like that) — pretty cool.

Tomorrow: Chemin (for chemistry and mineralogy).