Beagle 2's approach will be to heat samples of soil or rock
in the presence of oxygen. Under these conditions all forms
of carbon are convertible to carbon dioxide, they either decompose
(carbonates) or they combust. We know that all organic
matter, no matter how complex or cross-linked, will burn and
convert to carbon dioxide thus maximising the chances of detection.
The process does not presuppose we know what compounds are biologically
significant on Mars - but we will detect any carbon .
Stepped combustion data from ALH 84001,106
Combustion, especially if it is done using a sequence of temperatures
(stepped combustion), has many other advantages. We can obtain
simple information about the complexity of the carbon structures
from the temperature of release, for example, biological compounds
burn in the 200 to 500 °C range, whereas a pure elemental
form of carbon such as diamond burns at considerably higher
temperatures. Most important for Beagle 2 is that the stepped
combustion method can resolve organic and inorganic types of
carbon thereby easily distinguishing between possible microbial
remains and carbonate minerals.
