My journey into the world of astrobiology began with a childhood love of space and plants, which grew and developed into interests that now lie firmly at the intersection between astronomy, biology and geophysics. A perfect place from which to explore questions about how life would influence a planet's atmosphere, climate, appearance and detectable signs of life (biosignatures). My research has encompassed everything from exploring exotic forms of photosynthesis on planets with two suns, to investigating the types of biospheres that could thrive on UV-irradiated worlds, and even looking at where the last puddle on Earth may be in the far-future and what this would mean for the search for life in the Universe. Interest in this kind of research reaches far beyond the scientific world, providing me with many public outreach opportunities through the written word, television, radio or science events. The more time I spend exploring these questions and talking to people about them, the more I am aware that they not only help us to determine how to search for life on distant alien worlds, but can also help us to build on our understanding of the complex interplay between the atmosphere, geosphere and biosphere here on Earth. This connection between other worlds and our own has been a significant driving force behind much of what I do.

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Research Interests


Astrobiology is concerned with the search for life beyond Earth, as well as the origins, limits and future of life in the Universe. It is truly interdisciplinary in scope, encompassing astronomy, biology, chemistry, geophysics and many other disciplines. In my work - initially at the University of St Andrews, then at the Carl Sagan Institute, Cornell University - I act as a bridge between astronomy and biology. I focus on using Earth as a template for how life would interact with the atmospheres and surfaces of habitable exoplanets. This involves using Earth-like ecosystems as a basis for envisioning possible extraterrestrial biospheres by finding the overlaps between the environments life has adapted to on Earth (or to which evolutionary biology suggests that life could adapt given the right 'push') and the environments we predict for potentially habitable exoplanets. These alien-but-familiar biospheres then become components of climate or photochemistry models to simulate how less Earth-like life might be detected.

One aspect of this involves studying the impact stellar evolution may have on the biospheres of planets in the habitable zone of their star (the region around a star where temperatures are just right for liquid water to exist). These impacts include how life would adapt to changing conditions over geological time, how remotely detectable biosignatures would change and, ultimately, when all life on a planet would come to an end. Another aspect of my research involves investigating how frequently-flaring, active red dwarf stars would affect the biologically harmful ultraviolet radiation fluxes on any closely orbiting habitable zone rocky planets, as well as the mechanisms life could employ to survive such harsh environments.

It is important to know how the signs of life change over a planet’s habitable lifetime, or how they could differ for the full range of possible habitable environments that could exist on rocky exoplanets. Near-future habitable exoplanet discoveries will not all be similar to the present-day Earth. Some may host younger, simpler biospheres, others may host older, dying biospheres, while others may host more alien biospheres, hardened to high radiation levels, or other extremes. Different subsets of the distribution of possible habitable environments could lead to life that is very different to the life we see on Earth today. Consequently, these scenarios will produce very different sets of biosignatures. Knowing what signatures to look for from these worlds will increase the chances of confirming the presence of life on a planet beyond our solar system.

These types of project require the blending together of knowledge from a wide range of fields, such as stellar evolution, planetary geophysics, atmospheric physics, biological evolution, environmental biology and ecology. Putting strands of different science together in this way to imagine alien worlds leads to new and novel ideas, as well as some very interesting collaborations. Perhaps even more importantly, it can give us new perspectives on our own planet and the fragile interplay of life, geosphere and atmosphere that makes it not just habitable, but home.

The specifics of my research themes and associated publications are detailed in the Research Themes section below.


Research Themes





24, Sep 2019

The Living Universe in Your Back Garden

As a guide to how to look for life on other planets, there is no need to look any further than your own back garden. Whether it sprawls over countless acres or is compacted into a small balcony, a garden artfully demonstrates the theories, methods and tools astrobiologists use in their search for alien life on worlds far beyond Earth. A garden is a cultivated space, forever being nudged away from the wilderness it desires to become by the hand that shapes it.

9, Aug 2019

A Clarification on CO2 and the End of the World

In the past few years, I have noticed my name cited in articles that attempt to debunk climate science. I ignored it at first, working on the assumption that most people either would never read these articles anyway, or would at least see through the agendas behind them. However, more recently, there has been a notable increase in such articles – particularly from within a certain country post-2017 ...

12, Jul 2019

Brexit and the Search for Life in the Universe

At first glance there seems to be little connecting Brexit with the search for life on other worlds (beyond, perhaps an impact on the funding of and involvement in that search). However, given time to think on it, odd parallels between the two begin to emerge. Over the three-and-a-bit years since the day of the June 2016 referendum, constant wall-to-wall media coverage of the UK’s plodding, tortoise-like random walk ...

29, Jan 2019

The Great British Weather and the Habitability of Other Worlds

Earth 2.0 has been a popular term in the media for many years now, despite the fact that – to date – no planet beyond our solar system has yet been found that can be confidently described as a copy of our world (let alone a superior, more advanced version of Earth as the postpositive 2.0 tends to imply). This has led to some prevalent misconceptions of the planets we have been finding recently.

15, Jan 2016

Predicting Evolution

Evolution is often thought of as a haphazard, random process, the results of which cannot be predicted. A famous biological thought experiment, dreamt up by Stephen Jay Gould, imagines re-winding the tape of evolutionary history on Earth, then replaying this “tape of life” from the beginning. Given the random nature of evolution, it is often thought that the new life history of the planet would look very different from the current one...

12, Mar 2015

A Glass of Martian Red?

Wine has been with us, in one form or another, for 1000s of years, its origin stretching back to before written records began. When people settled new lands, they brought their vines with them, spreading viticulture across the world. If and when people settle on Mars (an idea that’s gradually moving away from the realms of fantasy and becoming a real possibility) they will almost certainly want to continue this trend...

10, Jan 2015

How interesting would the discovery of alien microbes really be?

Recent evidence suggests microbial life may have been present on Mars, deep in that planet’s past. Some microbes have been exposed to space and survived, suggesting they are tough enough to endure incredibly harsh conditions If life is something that originates easily, then it is probably only a matter of time before...

18, Dec 2014

Where did all the water come from?

It was recently announced that the Rosetta space mission to the comet 67P/Churyumov-Gerasimenko found that water contained by the comet did not resemble water on Earth. This has added to evidence that comets probably did not deliver the oceans to our planet billions of years ago when it first formed. In that case, where did all the water come from..?

3, Oct 2014

Life in the Air

On Earth, life has managed to find a foothold in a range of seemingly inhospitable environments. Often the most extreme of environments are solely the domain of microbes; from the hot, high-pressure environments of deep sea vents, to the insides of nuclear reactors, but not always. There are also ice worms that spend their lives in glacial ice, so adapted to the cold that they would melt in your hand if picked up...

22, Aug 2014

Are we still trying to answer the same questions as ancient astronomers?

Of all the sciences, astrobiology seems to capture the public imagination in a way that no other topic does. The quest to find other worlds like our own and to find life on other planets is something that people from all walks of life get excited about...

12, Aug 2014

Will we really find any signs of life beyond Earth?

Astrobiology is a science with little to no evidence. We know there is life here on Earth and, because Earth is in no way separate to the rest of the universe, we know that there is life in the universe. However, when it comes to looking for life beyond Earth we really have nothing much to go on...yet. By studying life on Earth we know increasingly more about where life could live...