Preparing to look for life in samples returned from Mars, without even lifting the lid
07 Aug 2026 - Rosie de Laune
A team from Birkbeck, University of London, and the Natural History Museum have combined neutron and X-ray tomography to understand whether the techniques could be used to look for signs of life in samples brought back from Mars.
So far, all investigations into Mars and its history have been done remotely on the Red Planet itself, or by studying meteorites. However, the NASA Mars 2020 Perseverance rover is collecting samples for a near-future Mars Sample Return (MSR), which will bring samples to Earth for analysis. These samples will be limited and extremely precious, and so developing methods to study them without causing damage is of key importance. There are also contamination issues to consider, and therefore finding techniques that could be used without even opening the sample containers would be even more valuable.
Both neutron and X-ray tomography are non-destructive and can penetrate through some sample holders, and so a group from Birkbeck, University of London, ISIS and the Natural History Museum wanted to test to see if these would be useful for studying Martian samples. They tested the techniques on Precambrian stromatolites (shown in the image on the right): fossils commonly thought to be similar to the rocks of astrobiological interest on Mars.
Previous studies have used X-ray microtomography (μCT) to study microbial biosignatures in fossils, thanks to the fact that the technique can produce high-resolution reconstructions of density-distinct phases. However, neutron tomography allows the characterisation of lighter element-dominated phases, such as those enriched in organic carbon and hydrogen, and therefore offers a different, unique, perspective.
They tested this combination of tomographic techniques on four samples, chosen to represent a variety of macro-morphologies common in Proterozoic-age fossils from this period.
They found that combining X-ray μCT and neutron tomography enabled them to comprehensively characterise the rock microstructure and mineralogy in 3D, including allowing them to detect organic materials with biological origin. Although the techniques still have limitations, they both present avenues for preliminary morphological and chemical analysis to help with the planning of further sample preparation and examination.
For example, tomography could help identify regions of interest for infrared and Raman spectroscopy, which would provide information about the presence of the functional groups most often present in biomolecules. Non-destructive imaging techniques could also help scientists select which areas of a sample should be taken for further analysis using more invasive or destructive methods.
“Our findings are of fundamental importance for planning for Mars Sample Return. They show that tomographic imaging should play an integral role in sample characterisation as part of the analytical strategy, especially because it can be performed with little to no sample preparation or damage,” says Keyron Hickman-Lewis, Lecturer in Planetary Exploration at Birkbeck, University of London, pictured, left.
The full paper can be found at DOI: 10.1029/2025EA004536
Our findings are of fundamental importance for planning for Mars Sample Return. They show that tomographic imaging should play an integral role in sample characterisation as part of the analytical strategy, especially because it can be performed with little to no sample preparation or damage
Keyron Hickman-Lewis, Lecturer in Planetary Exploration at Birkbeck, University of London
