Illustration courtesy of ESA Mars Exploration image:41562:3::0

But first you have to go looking around inside rocks on Earth, to get your theory in working order.

Space Daily:

Studying seven samples of the mineral jarosite collected from various places on Earth, a group of researchers was able to identify amino acids, the basic components of proteins, that had presumably been incorporated into the mineral's crystal structure.

Although not the first time biological compounds have been detected inside rock, the new method has the advantage that it works "at very low concentration without prior sample preparation," said Nancy Hinman of the University of Montana.

Yes, they found some jarosite on Mars. Originally, it was part of the argument that there was once water on the Martian surface. Then the analysis started putting the pieces together. A bit of geology opened up a very appealing line of reasoning:

…But there is something else about jarosite that makes it interesting. One of the steps in its formation involves combining pyrite (ferrous sulfide) with oxygen. This oxidation reaction can be performed by certain "rock-eating" microorganisms.

"The rate of the jarosite formation would be extremely slow without microbes and the presence of water," Hinman said.

Whether jarosite can form without the assistance of these microbes is very difficult to say, since every corner of Earth is occupied by little bugs of some sort or another.

So what you do is you sneak up on a planet with your analyzer, and you go looking for pyrites.

Jarosite isn’t very fussy about what gets into its chemical makeup. The chances are that remnant fragments of Martian life might be found.

There are skeptics:

"It's a very oxidizing environment on Mars," explained co-author Michelle Kotler, also from the University of Montana. Jarosite could therefore arise from chemical weathering of the planet's abundant basalt rocks.

Maybe so, but “weathering” is a fairly ambiguous term to use about Mars. Weathering by what? Active chemistry isn't the most immediately obvious force at work on Mars.

Another problem is that actually separating and identifying the organic materials from the jarosite isn’t likely to be easy, and there’s a risk of contamination. Chemical techniques are risky.

Laser techniques, using a mass spectrometer, however, have proved pretty reliable, one test identifying an amino acid, glycine, with the help of a mass spectrometer.

This kind of testing won’t be happening overnight on Mars, but it’s considered feasible enough for some forward planning:

"The advantage of our method is that it doesn't need sample preparation," Kotler said. "We just put the rock in the machine and shoot it."

Not only can their technique identify organics, but it can also measure the isotope ratios of carbon and other elements. If the accuracy can be improved, this measurement could potentially tell researchers whether the organic molecules they find came from living things or not.

The last paragraph in Space Daily’s article needs some explanation:

"One thing that is becoming clear is that the total scientific return on [a sample return] mission would be dependent on the diversity of the sample collection, and it is important to plan for ways to optimize that diversity," Beaty (chief scientist of the Mars Exploration Directorate at the Jet Propulsion Laboratory) said.

Translation: A “sample return” mission means anything from a manned landing to a returnable robot to more landers. “Diversity” means “ number of samples per buck spent”.

Which is another reason that a laser that can just sit there firing at rocks and getting reliable samples is a pretty attractive research tool.

Once upon a time, there was a theory that humanity would get its act together, and do things efficiently.

Space would be “conquered”, not just have a few odd machines thrown at it.

Now, when we talk about space, we’re talking about bringing in the tilers, not whole new rafts of technology which have been moldering on the planning committees for decades thanks to the lack of education of politicians, industrialists and financiers.

These are the Dark Ages of science, as well as society.

Superstition is now based on spreadsheets, with mystics devising virtuous payloads, but one day it will happen.