2.2 Organic contamination
As well as microbes themselves, you learned earlier that the detection of organic building blocks or remnants of microbes might also be compromised by contamination from Earth. In this section we discuss what organic contamination is and how and why we need to differentiate between compounds that have been produced by ‘life’ or produced by non-life processes.
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How might we describe processes that form organic molecules without living organisms?
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Abiotic (non-living) processes can form organic molecules without the involvement living organisms. Processes that involve life are described as biotic and can result from organisms themselves, their waste products and the interactions between organisms.
In the context of planetary protection, organic molecules unrelated to biology that can cause contamination are classified as molecular organic contamination (MOC). These can be found on surfaces, be used to manufacture spacecraft (e.g. lubrication or bonding), or be in the environment around the spacecraft. Their presence can degrade the performance or lifespan of the spacecraft, as well as make it harder for us to decide if an organic compound is a biosignature or MOC. We also don’t want to contaminate space with organic compounds that could be detrimental to pristine environments.