Astrobiology is a new field of science, investigating the possibility of life existing beyond the Earth. Astrobiology is a deeply interdisciplinary field, with biochemists, microbiologists, geologists, planetary scientists and astronomers all working together on this search for extraterrestrial life. Here at UCL, the group is focussed on ultra-hardy lifeforms, known as extremophiles, which thrive in some of the most hostile environments on the planet. Scientists in the lab are working on microorganisms we have isolated from inhospitable environments including the Dry Valleys of Antarctica, the volcanic icefields of Iceland, and the very salty and alkaline soda lakes of East Africa. By studying the survival of these organisms we can understand better the broad range of conditions and environments that can support life, and therefore where best to search for life beyond Earth.
An astrobiological study of high latitude Martian-analogue environments
Exploring volcanic environments on Earth can help us understand past or present habitats on Mars. In particular, we are identifying the bacterial and archaeal diversity of environments produced through subglacial volcanism. The eruption of basaltic lava into overlying ice leads to a number of exceptionally varied lithic, hydrothermal and icy habitats, which serve as analogues for past environments on Mars where subglacial volcanism is likely to have been common throughout its history.
We have identified bacterial communities inhabiting basaltic lavas with different physico-chemical properties, showing how lithology may have an important influence on the development of a microbial community within an extreme cold and dry environment. In addition, we have found selected members of these basaltic lava communities remain viable under present-day Martian conditions whilst incorporated into a subglacial volcanic ‘microcosm’. One particular species – a close relation of Rubrobacter radiotolerans – was able to survive full exposure for up to a week.
Astrobiological effects of the cosmic radiation on Mars
One of the locations in the solar system thought most likely to be able to host life, at least in its past, is Mars. The current martian surface is exceedingly cold and dry, however, which would pose a severe restraint on the survival of life. The Dry Valleys region of Antarctica is a good analogue site to the martian surface, and I have isolated hardy bacteria from this environment that can survive very cold and dry conditions. Another major hazard on the martian surface is the constant flood of cosmic radiation, and I perform gamma-ray survival studies on my Antarctic bacteria as well as Deinococcus radiodurans, the most radiation-resistant organism known on Earth. Over long periods of time this cosmic radiation would act to degrade any signs of extinct life on Mars, so I am also investigating how long different 'biosignatures' would persist before we can no longer detect them.
Survivability of microorganisms from alkaline environments under Martian conditions
We have sampled and isolated organisms from a variety of environments, in particular from Lake Magadi, a soda lake in Kenya. The environments sampled have a high pH (>9) and salt content. We are investigating the culturable diversity from samples of water, soil and biomass using media based on sample location chemistry. The cultured organisms we isolate are being used in Martian simulation experiments to look at their survivability under conditions like those found on Mars.
This work is funded by the Natural Environmental Research Council and is in conjunction with the Department of Earth Sciences UCL and the Centre for Planetary Sciences at UCL/Birkbeck. Field work was completed with assistance from Professor E. Odada at the University of Nairobi and The University of Cardiff.
The Mars chamber work is with Dr Manish Patel at the Space Sciences Research Institute at the Open University.