Rocks with a high carbonate content are amongst the richest in organics. The process of stepped combustion can differentiate between any organic matter found in rocks and any carbonates because the latter won't break down to carbon dioxide unless much higher temperatures than those involved in the experiment are applied to the rock samples. Beagle 2 will be performing the stepped combustion experiment on the surface of Mars, hoping to capture large amounts of carbon 12 in the carbon dioxide gas given off by samples as they are gradually heated. Sniffing the Air Methane is a common gas on Earth. It is also extremely unstable in our atmosphere.
Photolytic reactions destroy methane at an incredible rate.
Methane is as equally unstable in Mars' atmosphere. Beagle 2 will carry equipment that will enable it to sniff the Martian air for signs of methane. This experiment is one of the cleverest on Beagle 2. The methods that Beagle 2 will use to make the necessary measurements were actually perfected for the purpose of understanding the process of global warming here on Earth, and so can easily spot methane at less than parts per billion levels on Mars. The equipment aboard Beagle 2 includes a robotic arm that can be used to deliver a number of discrete packages directly to the surface of Mars.