Curiosity is a historic achievement. It is the biggest and most complex instrument we have ever landed on another planet. Virtually every T-shirt I have purchased since it landed has had a NASA logo on it. I am very very proud of the scientists and engineers who have made this possible. I am, however, very disappointed in the level of sophistication of the Mass Spectrometer on the Rover.
This is a schematic of SAM (sample analysis at Mars) lab. The first thing you'll notice is that SAM uses a quadrupole mass spectrometer. Sure. This makes sense. Quads are robust and can take a jarring without requiring constant recalibration. The mobile mass spectrometers the military uses for detecting chemical warfare agents are almost exclusively quad instruments.
The disappointment comes in when you look at the capabilities of this mass spectrometer.
The above mass spectrum was taken from this paper detailing the calibration of the quadrupole unit from Curiosity. I understand, we are taking this instrument and shooting it to another planet, but are we looking at mass accuracy within +/- 1 Da? That is what I get. 1 Da? Now the quad has a really interesting mass range, from 2 - 550 m/z. That is a tough range to work with, but 1 Da? A guy I've been working with this week has been working with small molecules <100 Da and has been consistently been pulling parts per billion mass accuracy. In my opinion, this is where our technology is today. I'm sure there are reasons for this drop off, but I can't help but be a little disappointed.