Astrobiology PhD Projects

Research projects on offer in our Astrobiology group

How biologically useful are the materials of the Universe?

Charles Cockell

Although we are familiar with how life uses materials on Earth, such as organics produced by other life, as a source of carbon and energy, beyond Earth there are materials that are less well understood with respect to their availability to life. For example, tholins are organic compounds produced by the irradiation of organic materials by ionizing and/or ultraviolet radiation and produced in prodigious quantities on Titan. What influence would they have on the habitability of a subsurface Titan ocean? Recent work in our laboratory has investigated how microbes use fullerenes, cage-like organic materials, which we think are produced in the interstellar medium and may have been delivered to early Earth when life first emerged. In this project, you will investigate the microbial use and processing of some selected extraterrestrial materials, including rocky substrates that represent extraterrestrial materials and some organic materials. Our goals are two-fold: 

1. To carry out fundamental scientific studies to understand how life processes extraterrestrial materials. This will allow us to understand whether early life on planets could use these materials delivered exogenously from space to build itself and it will reveal the types of early metabolic pathways that could have been used by life. This work will involve microbial and molecular methods to elucidate the pathways by which life accesses and processes extraterrestrial materials. These findings will help elucidate the conditions that allow for habitability and can inform space missions searching for habitability and life beyond Earth.
2. To understand how we could use microbes in processes to support the human exploration and settlement of space. Can we process asteroids and other extraterrestrial rocks and materials to support a human presence in space? This work will involve data from our first goal to explore how these pathways could be manipulated and used to support human space settlement.

References:

Nixon SL, Cockell CS. 2015. Nonproteinogenic D-amino acids at millimolar concentrations are a toxin for anaerobic microorganisms relevant to early Earth and other anoxic planets. Astrobiology 15, 238-246.

Cockell CS, Santomartino R, Finster K, Waajen AC, Eades LJ, Moeller R, Rettberg P, Fuchs FM, van Houdt R, Leys N, Coninx I, Hatton J, Parmitano L, Krause J, Koehler A, Caplin N, Zuijderduijn L, Mariani A, Pellari SS, Carubia F, Luciani G, Balsamo M, Zolesi D, Nicholson N, Loudon CM, Doswald-Winkler J, Herova M, Rattenbacher B, Wadsworth J, Everroad RC, Demets R. 2020. Space station biomining experiment demonstrates rare earth element extraction in microgravity and Mars gravity. Nature Communications 11, 5523.

Cockell CS. 2021. Bridging the gap between microbial limits and extremes in space: space microbial biotechnology in the next 15 years. Microbial Biotechnology 15, 29-41.

Santomartino, R et al. (2023) Toward sustainable space exploration: a roadmap for harnessing the power of microorganisms. Nature Comms 14, 1391.

True and false signatures of habitability and life on exoplanets

Sean McMahon & Beth Biller

More than 5,000 exoplanets have now been discovered and confirmed; thousands more detections await validation. In coming decades a new generation of space- and ground-based telescopes will collect light transmitted, emitted and reflected by these distant worlds, providing spectra in which the fingerprints of diverse chemical, mineralogical and perhaps biological substances might be detectable. For example, we may be able to: (1) resolve surface reflectance features such as the “vegetation red edge” due to chlorophyll and other biological compounds; (2) observe mineralogical features that shed light on the geological history of exoplanets, including their past and present habitability; (3) test models for exoplanet chemical evolution. To prepare for these exciting future possibilities, it is now critical to catalogue, disambiguate and interpret the spectroscopic features of minerals, biomolecules and other materials relevant to the spectral range and resolution of next-generation telescopes.

This project will focus in particular on generating and analysing reflectance spectra in the visible-to-infrared range, as part of an ongoing collaboration between Edinburgh (Sean McMahon, Beth Biller and the UK Centre for Astrobiology) and Cornell (Lisa Kaltenegger and the Carl Sagan Institute). Using benchtop spectroscopy experiments as well as atmospheric models and telescope simulators, we can formulate and test hypotheses about what to expect from future exoplanet observations. The data we generate will help us to understand not only how to detect spectroscopic biosignatures, but how non-biological features of exoplanets may mimic these signatures of life. They also provide surface albedo input parameters for atmospheric models of these worlds. This project will involve a combination of laboratory spectroscopy and computational approaches and can be flexibly adapted to the interests of the student.