EXPOSE-R2: Life in space? Life on Mars?

Scientists have put organisms on the outside of the International Space Station to if and how they’ll survive in space and to investigate how their component molecules survive. Many factors such as radiation, lack of oxygen and extreme temperature changes might make you think that life won’t survive exposed to outer space. But if it does survive, looking at how, why and where will help us to understand the origins of life and where else to look for it beyond Earth.

Scientists trying to unravel the origins of life often study organisms in extreme conditions – the Arctic and Antarctic; the Atacama desert; acidic rivers such as Rio Tinto in Andalucía; deep-sea thermal vents and so on – to learn more about the limits to life and how organisms adapt to different environmental conditions. This has implications for how life may have arisen and evolved on the early Earth, and on other places in the Solar System, such as Mars or the moons of Jupiter.

The unique orbital laboratory of the International Space Station (ISS) allows us access to another extreme environment – space – with a combination of conditions not present on Earth, and gives scientists the opportunity to study how organisms react in a highly controlled way. There are a number of aspects of being exposed to the space environment which have implications for our understanding of how and where life can survive: the different radiation conditions; the extreme vacuum; the extreme changes in temperature.

EXPOSE is a facility mounted outside the ISS dedicated to astrobiology, developed by ESA to allow exposure of chemical and biological samples to outer space. A combination of in situ measurements and laboratory analysis of samples returned from space is used. EXPOSE R-2 is the third in a series, following successful missions launched in 2008 and 2009 – one mounted onto the exterior of the European Columbus module (‘EXPOSE-E’), one mounted on the Russian Zevzda module (‘EXPOSE-R’).

EXPOSE-R2, also mounted outside the Russian module, will fly for 18 months (starting in August 2014 and ending in April 2015), and has two main experiments: BIOMEX and BOSS, both with significant involvement from Professor Charles Cockell, University of Edinburgh.

BIOMEX is studying whether life or its component biomolecules survive on the surface of Mars. There are many different compartments, each containing different organisms, such as bacteria, algae, fungi. Some of these will be protected by an artificial Mars soil, to a variety of depths, and some will even have a ‘Martian’ atmosphere, rich in carbon dioxide, whilst others will be left entirely exposed to space. This will help understand the habitability of the Martian surface and inform future exploration of the Red Planet.

BOSS (Biofilm Organisms Surfing Space) is studying biofilm and non-biofilm forming organisms, comparing how they respond to UV radiation. It is thought that biofilm forming organisms may be better able to withstand UV radiation; this experiment will test this idea, and try to answer why that may be the case. This will improve understanding of where and how microbes can thrive, with implications for better understanding biofilms, and microbial resistance, on Earth.