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Louisa Preston works in extreme environments - from volcanoes on Hawaii to acidic rivers in Spain and hot springs in Iceland - to find extremophiles: organisms that thrive in these otherwise uninhabitable places.

Preston, 33, an astrobiologist based at Birkbeck, University of London, recently wrote a book, Goldilocks and the Water Bears: The Search for Life in the Universe, about her research. She studies these habitats and organisms as analogues for how life might survive on planets such as Mars.


As part of her research, she also runs analogue missions in these remote locations, to test the technologies that could be used in space. WIRED spoke to the UK Space Agency Aurora Research Fellow about how analogue missions work on Earth, the extremophile that inspired her book, and the possibility of life on Mars.

WIRED: What are you researching?

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Louisa Preston: I'm studying different environments across Earth, like sub-glacial volcanoes, ancient rivers and impact craters, which look like what might be on Mars. On Earth, these types of environments have extreme-loving organisms that can live in harsh conditions that may have the potential to live on Mars today, or to have lived there in the past. So I'm studying them on Earth to figure out how they could survive on Mars.



How do you define what you're looking for?

The good thing about looking for organisms that might live on Mars is that chances are, they're going to be quite simple organisms like bacteria, which means there's only a certain number we're looking at. Ones that can survive the cold, extreme radiation, or acid conditions - those, we are interested in.



The tardigrade, or water bear, features in the title of your book. What makes it a prime example of an extremophile?


Tardigrades are found across the Earth in rainforest canopies, on mountain summits and beneath the frozen desert of Antarctica. Yet I've personally found many happily living in regular garden moss. If it feels itself under stress, in an environment without enough water or oxygen, it rolls into a tight ball called a tun, and expels about 97 per cent of its body moisture. It essentially becomes a mummified ball of the ingredients of life. We don't actually know how long it can stay in that state - at least 100 years, possibly longer. It just waits until conditions improve.

A project called Biokis, sponsored by the Italian Space Agency, took water bears into space - albeit in the tun state - and when they came back to Earth they uncurled in minutes and carried on with their lives. So if there was ever

an organism that was able to survive on Mars, it would be a water bear.1

Preston runs analogue missions to see how life survives in harsh environments on this planet, and what it means for future space exploration Jamie Jones

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What's the purpose of running analogue missions on Earth?


Analogue missions were created to be the drivers of technology, and for us to practise going to other worlds. The Apollo astronauts did the same thing in Iceland to practice for the Moon. I spent a number of years running missions where we would simulate sending astronauts and rovers to impact craters, asking, what does that tell us about how we could refine operations on the Moon? That just gets extended to Mars.

I'll be working this year in Utah's desert, in a collaboration between the UK, Canada, America and Europe, to run another analogue mission to figure out how we can make rovers and mission control teams more efficient at their jobs, when we do send them on real-life missions. But also, we want to get our own science done. Quite often when we do these analogue missions, we choose alien-like on purpose, with geology or extremophilic organisms that mimic where we

might do research on other planets.

Does our growing knowledge of space shape how this plays out on Earth?

Absolutely. We're lucky to live in a time where we've got such wonderful images of Mars. We see signs on them and think, "I wonder if there's something like that on Earth?" whereas in the past it was about understanding the Earth and thinking, "That thing on Mars actually looks like this thing on Earth." They're interchangeable - the more we learn about Mars, the more we learn about Earth, and vice versa.



In October, the ExoMars Trace Gas Orbiter (TGO) and Schiaparelli Mission will arrive on Mars to look for evidence of life. How important is this mission to you?

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Disclaimer: This interview took place before the Schiaparelli lander crashed on its descent to Mars.

It's really important. It's got two missions: the first is to deliver Schiaparelli, an entry-descent module, to Mars. Its main job is to land safely and test all the procedures for landing that will be used when we send the ExoMars rover in 2020. Then the Orbiter is going to orbit Mars until 2022, effectively sniffing the atmosphere for methane and other types of carbon gases.2

The goal of TGO is, first off, to find the methane and map it. It's also to figure out if that methane is biological or not. If it is, we have two options: either, once there was life on the surface of Mars that produced methane, which got trapped inside ice in the ground and as it started to melt the methane got released in bursts. Or, the more exciting option is that there is methanogen and methane-loving organisms under the surface of Mars, pumping it out.



How are you involved?


I'm more involved with the ExoMars rover that's being sent in 2020 than this mission. I'm using my knowledge of extreme Mars-like environments on Earth and their diverse ecosystems to test an instrument that mimics that of ExoMars's infrared spectrometer. The goal is to identify signatures of life within Mars-like samples using Mars-like equipment, ahead of time, so that once we're on the surface we know what we're looking for.3 So I'm involved in helping to scout out environments where we might be able to test this instrument, to provide samples and help interpret the data.



What are you working on next?

I'll be heading to Iceland soon to look at hot springs and outflow deposits from volcanoes that have erupted underneath ice sheets. We'll be using some of the prototypes going on ExoMars to see what we can identify.

I'm also diversifying a bit: I'm going to Lake Tirez in Spain, and instead of Mars we're using it as an analogue for Europa, the icy moon of Jupiter. The hyper-saline waters here may bear chemical similarities with Europa's hidden liquid ocean - and there's extremophilic life living inside these salty waters and sediments. So we're going to see how life survives and is preserved here, and, if we simulate the environment on Europa, what happens to this life and its biosignatures.

1. Angela Maria Rizzo, 2015. "Space Flight Effects on Antioxidant Molecules in Dry Tardigrades: The TARDIKISS Experiment," BioMed Research International Volume 2015 Article ID 167642





2. ExoMars trace gas orbiter





3. Louisa J. Preston, 2015. "Fourier Transform Infra-Red (FTIR) Spectral detection of life in polar subsurface environments and its application for Mars exploration," Applied Spectroscopy, Volume 69 Number 9, 1059-1065





