Seeking Signs of Life: Astrobiology at 50

Seeking Signs of Life:

Astrobiology at 50

Last week, I was a very privileged observer at NASA’s symposium, ‘Seeking Signs of Life’, to celebrate the 50th anniversary of the exobiology program.  A day-long symposium covered everything from the founding politics and economics of the program, to the fantastical predictions for the next 50 years.  More than anything, it reaffirmed for me how fantastic and forward looking the multidisciplinary astrobiology community is, and how very much I want to continue to be a part of it.

The event ran from 9 am to 5 pm, and was webcast live from the Lockheed Martin Centre in Arlington VA.  Archived videos of the three keynote presentations, and the four panel discussions can be found here.  The following is a brief review of the day to whet your appetite!

Keynote: James Lovelock and Lynn Margulis: Exobiology in the Beginning

After opening remarks from James Green, the first keynote was delivered jointly by Professors James Lovelock (University of Oxford, UK) and Lynn Margulis (University of Massachusetts Amherst).  Professor Lovelock is best known for formulating the Gaia hypothesis, now approached scientifically as Earth System Science, but has also played a major role in life detection in the solar system and beyond.  He spoke of his life as a researcher, describing in a personable and charming way his work on red blood cells, on the life detection equipment for Lunar and Martian missions, and on the speedy scientific revelation that entropy reducing life will modify an atmosphere away from thermodynamic equilibrium, something which may be detectable in distant exoplanets.  He politely and offhandedly dismissed the idea of Earth lying within the ‘Goldilocks Zone’ as a ‘silly idea’, as the planet requires life to modify it to make it habitable.

Professor Lovelock was followed immediately by Professor Lynn Margulis who, in her own characteristically eccentric way, reinforced Prof. Lovelock’s comments on the Gaia hypothesis, declaring that we may now call it the Gaia theory, and treat it accordingly.  She urged the importance of water to life on Earth, and the importance of life to water on Earth.  She ended by proposing changing the name of the planet, to Planet Water.

Panel 1: The Origins and Evolution of Exobiology and Astrobiology at NASA

The first panel discussion was entitled ‘The Origins and Evolution of Exobiology and Astrobiology at NASA’, and was chaired by Roger Launius, from the Department of Space History, at the National Air and Space Musuem, Washington DC.  Speaking on the panel were Steven J. Dick, former Chief Historian at NASA, Baruch S. Blumberg, from the Fox Chase Cancer Centre, and Noel Hinners formerly from Lockheed Martin and Director of the Goddard Space Flight Centre.

Steven Dick spoke about the early genesis of astrobiology, citing Percival Lovell as a major trigger in sparking interest for life on Mars.  We were told how Josh Lederberg was a catalyst for the astrobiology program at NASA, and was the first to coin the term ‘exobiology’.  But why was NASA the one to lead the search for life?  Not only because they were the ones going to Mars, he said,  but also because they had an active policy of looking for ‘diamonds in the rough’, for funding exciting but non traditional projects like Lynn Margulis’ symbiogenesis research, and James Lovelock’s Gaia project among many others.

Noel Hinners addressed the audience next, dealing principally with the topic of the Viking landings in 1976.  He told us how the Viking program was NASA’s first real search for life, and how the public were led to expect a positive result from it.  Thus the disappointment felt by them and scientists around the globe caused a long hiatus in Martian exploration not only for the American space program, but for the Soviets too.  Dr Hinners expressed his belief that the Viking program was premature, and that we really need significant knowledge about a planetary body before we can design the best suite of life detecting equipment.  He believes that a major priority should now be a Martian sample return mission, as there is no substituting a full terrestrial lab.

Finally, Baruch Blumberg spoke, giving a potted history of the NASA astrobiology program.  He listed a large number of major players involved from the start, many of whom are major NASA household names.  He described the importance of the Martian meteorite ALH84001 (which was purported to contain several lines of evidence pointing to fossil life) in sparking debate and generating new ideas and hypotheses in astrobiological research.  Further, he talked of his time as a research director, and how he gave his researchers relatively free reign in order to increase quality as well as quantity of results coming out of NASA.

Panel 2: Understanding the Origin, Evolution and Distribution of Life in the Universe

Following this, the second panel discussion, chaired by Lynn Rothschild of the NASA Ames Research Center, was entitled ‘Understanding the Origin, Evolution and Distribution of Life in the Universe.  The panel members were Pamela G. Conrad, from the Planetary Environments Lab at the NASA Goddard Space Flight Centre, Martin Brasier from the Department of Earth Sciences, University of Oxford, and John Corliss, from the Department of Environmental Sciences and Policy, Central European University.

Dr Rothschild presented a concise and informative introduction to the session, defining astrobiology as the three questions:  Where did we come from?; Are we alone?; and Where are we going?, the first of which falling within the remit of the panellists.

Pamela Conrad spoke first.  She described her work on modelling habitable zones around stars, stating that above all else, a habitable environment depends not only on location, but also on raw materials and on timing.  Thus, the nature of the habitable environment and the nature of the inhabitants are inexorably entwined.  She mentioned the likelihood of a habitable environment on Earth during the Hadean (4.6 – 3.8 billion years ago), and listed among other things the necessity of a magnetic field and physically stable rocks to make an environment conducive to life.

Following this, Jack Corliss spoke on the research topic that has become his life’s work: the synthesis of life around hydrothermal vent systems.  He described how the submarine hot springs were detected remotely, and an expedition planned to investigate, using the submersible ‘Alvin’.  After finding these hydrothermal systems teeming with life, Dr Corliss said that the hypothesis of life originating here ‘seemed obvious’.  In a series of well presented illustrations, he described how synthesis of organic molecules, organisation into cellular structures, and the adaptation of metabolic processes may all occur at different points within the vent system.

Professor Brasier concluded the session concisely with the presentation of a new concept in the study of Mass Extinctions.  He described how, although many extinction events have been accounted for by meteorite strikes, lava flows, and ice ages, these events occur frequently elsewhere within the rock record, without having the same effect on the biosphere.  The explanation for this is that the extinctions are driven chaotically, by the collapse of highly interconnected systems.  In short, the state of the ecological system determines that small triggers can have large, non-linear consequences.

Following a brief lunch, an award ceremony took place, where various senior contributing members of the program were honoured for their service to the scientific community.  Among those recognised were Professors Lynn Margulis and James Lovelock, Michael Meyers, and Baruch Blumberg.

Keynote: Daniel S Goldin

Next on the agenda was the second keynote address, delivered by NASA Administrator Daniel S. Goldin.  He spoke of his time at NASA, seeing it through 3 presidential administrations, and the accompanying political and economic changes.  The tone of his address seemed somewhat melancholy, bemoaning slow moving NASA for missing out on the biological revolution of the 50’s and 60’s, the lingering bad image of the Association following the Apollo and Challenger catastrophes, and the continuing budgetary constraints on the space program.  The content wasn’t all negative though.  He described the continuing excitement of the public in response to the astrobiology program and the search for life, despite the lack of concrete results.  Further, he expressed the encouraging conclusions from meetings with worldwide religious leaders, that the search for life was not in conflict with those religions.  He concluded on the positive note that Exobiology and Astrobiology represented an unprecedented merging of all disciplines, and that by competitively engaging organisations rather than individuals, the field can remain sustainable and productive.

Panel 3: Who Are We? Where Are We Going? Are We Alone? Astrobiology in Culture

Following this, the third panel discussion of the day, chaired by Linda Billings of the School of Media and Public Affairs at the George Washington University, was entitled ‘Who are we? Where are we going? Are we alone? Astrobiology in Culture.’  Sitting on this panel were Marc Kaufman, Science Writer at the Washington Post, Connie Berkta from the Geophysical Lab at the Carnegie Institution, and David Grinspoon, Curator of Astrobiology at the Denver Museum of Nature and Science.

Linda Billings began by introducing the panellists with respect to their journalistic and academic publications, and went on define culture as a process by which reality is maintained and transformed, explaining how astrobiology, being of international interest, plays a fundamental role in cultural development.

MarkKaufman began by professing to not being a follower of Star Trek or of NASA but maintained that this gives him the opportunity to give a public view of the astrobiology program. He went on to say that the public is in fact fascinated by the search for extraterrestrial life, with as many as 80% of polled Americans believing there is life elsewhere in the universe.  Further, he applauded the efforts of scientists involved in astrobiology, in their efforts to help him as a non-scientist understand concepts central to their individual research.

Connie Bertka followed, and with her background in science and religion, was able to give a more theistic view of the search for life, already previously touched on my Daniel Goldin.  She made the point that when children inevitably ask the questions central to the astrobiology program: ‘Why are we here? Where did we come from?’ and ‘Where are we going?’ then most parents will turn not only to science, but also to religion, for answers.  She presented the figure that 42% of Americans still don’t accept the concept of evolution, and that this figure hasn’t changed in 50 years.  Such a fact is discouraging, and it contributes to making the question of the origin and evolution of life especially challenging, as most people turn to religion.  However, she said, the numbers of people describing themselves as ‘Spiritualist’, both from a theistic and an atheistic point of view, has risen, and this reflects an encouraging increase in independent thought, rather than institutionalised religion.

Finally, we were addressed by David Grinspoon, who as the only curator of astrobiology in a major museum, can claim in his collection such artefacts as the original Miller-Urey apparatus, and many Earth and space rocks illustrating the search for life.  He discussed how astrobiology at NASA has an excellently integrated Education and Public Outreach  program, that is helping improve the reputation and image of scientific debate.  He mentioned how truly interdisciplinary astrobiology is, and how it is a fun and positive way of presenting scientific connections to the public.

Panel 4: Homing in on ET Life: Where and How to Look

The final discussion panel of the day was entitled ‘Homing in on ET Life: Where and How to Look’, and was moderated by Michael A. Meyer of the Mars Exploration Program at NASA HQ.  Panellists were Daniel P. Glavin from NASA Goddard Space Flight Centre, Victoria Meadows from the Virtual Planetarty Laboratory at the Department of Astronomy, Univeristy of Washington, and Steven A. Benner from the Foundation of Applied Molecular Evolution.

Daniel Glavin was first to speak, and he described the excitement that the discovery of organic compounds and materials in meteorites such as the Martian rock ALH84001 and the carbonaceous chondritic Murchison meteorite.  Despite the fact that life signatures in ALH84001 have been all but disproven, the stir that their initial report caused is undeniable.  Results from the Murchison meteorite and others showed that there are without a doubt organic compounds in space, as well as abundant carbon bombarding all cosmic objects.  The major challenge however, he said, would be finding a signature for life among that abundant carbon, and that this would be a target for the upcoming Mars Science Laboratory rover to be launched this year.

Vikki Meadows followed, with a discussion of the search for life outside the solar system.  She began by questioning: ‘Where is life most likely to be?’ As energy and nurtients are fairly easy to come by around stars, the so-called rate limiting step would be the presence of a liquid solvent such as water.  Thus, she said, the habitable zone around a star where it is neither too hot or too cold for liquids to exist, would be the best place to start looking.  She maintained that this may not be the only place that life exists, but that in the great vastness of space, it is the best place to start.  She finished by mentioning some of the exciting possibilities for detecting life on extra solar planets, such as looking for the ‘glint of light reflecting from off oceans’ or the characteristic reflectivity of forests.

The panel was concluded by Steve Benner, who began by distributing five beautiful rocks around the audience, two of which were real fossils, and three remaining questionable.  His point in doing this was to demonstrate the difficulty in identifying historical life here on earth, let alone elsewhere in the universe.  He discussed how, in trying to define life, our ‘Laundry List’ only describes terrestrial life, and that it may be different elsewhere.  Even scientists from different disciplines take different views, he said, quoting that modelling physicists and biologists believe life is easy to start, whereas chemists see the chemistry of life as extremely difficult to get going.

Keynote: Steve Squyres: The Next 50 Years

The concluding keynote address was delivered by Steve Squyres of the Department of Astronomy, Cornell University, and looked forward to the next 50 years of the Exobiology Program.  Being primarily concerned with Martian exploration Professor Squyres focussed on the fascinating topic of explorative missions to be considered in the Decadal Plan and beyond.  The day could not have ended on a more exciting and engaging topic.  Stressing that none of the missions he was about to describe would necessarily be pursued within the next ten years, he went on to outline marvellously fantastical proposals for investigating Venus, Titan, Mars, the Moon, Asteroids and Comets.  Comet surface sample return to non-cryogenically collect and return cometary material to Earth; a Mars trace gas orbiter to monitor the composition and distribution of methane on the red planet; and the Mars Polar Lander to observe changes in the polar ice caps and potentially look for life, were among some of the far reaching but achievable goals.  Longer term mission proposals included a three-phase Martian sample return, a Titan lake lander and submersible suite, and a Europa ice drill and submersible.  I personally sat, open mouthed and amazed that these missions were being seriously considered and could take place within my lifetime.

What a fantastic way to end the day!  As I shuffled out among NASA’s brightest and best, I was filled with an overarching sense of awe and motivation.  To be a part of this world, whether academic or professional, is a privilege that a meeting like this can really help to push home.  I look forward to the next 50 years!

Don’t forget, that the archived videos can be found here, also watch this space for further comments and discussion on some of the topics discussed at the symposium.

Intelligent Life: Apply Elsewhere

As I am in Edinburgh at the moment, and super duper busy as well as mostly occupied with non-sciencey things, I thought now would be a good time to share a previously written introductory article on Astrobiology to tide us by….  This article was featured in issue 5 of Bang! the Oxford Science Magazine…

Are we alone? Is there life out there in the vast expanse of space? Such questions have long been the domain of fantastical science fiction, and when we think of extra-terrestrial life, we think inevitably of tall green anthropomorphic aliens – the eponymous ET. But for nearly 50 years, the search for life in the universe has been a scientific pursuit too. In 1961, the field of astrobiology – the search for life beyond our terrestrial backyard – was born with the formulation of a simple equation.

Frank Drake, an astronomer and astrophysicist, was one of the first scientists to start looking for life in the universe. Using radio-astronomy, scanning celestial objects on radio frequencies, he chose normally quiet frequencies to listen for possible alien communication. Listening to two stars, both a similar age to our sun, for six hours a day over four months, Drake was confident that if there were communicating life forms out there, we would find them. When the vast data set was examined for patterns, all that was discovered was a secret military satellite. No, ‘Hello, we’re over here!’ from 11 light years away; no help beacon from a dying civilisation; no indication, in fact, that anything was out there.

So is that it? Does a lack of radio signals on a single frequency mean that humans are the only intelligent life form in the entire universe? Put like that, it seems far from conclusive, and in 1961 Drake attempted to quantify the probability of there being intelligent, communicating civilisations in our galaxy – cue the ‘Drake Equation’(see below). Its purpose is to break down all the factors necessary for a communicating civilisation to develop, apply a probability to each, and thus predict the number of civilisations we could list in our galactic phonebook.

Drake Equation

The Drake Equation, kindly drawn by Anna Pouncey, 2010

This was an insightful, reductionist way of dealing with the problem. Unfortunately, many of the factors were either unknown or unknowable. The ‘lifetime’ of a communicating civilisation, for example, lies more in the social sciences, and cannot even be statistically tested with our current sample size of one. Nevertheless, even conservative estimates of each of the factors gives a number greater than one. As such, enthusiasm for the search for life in the universe has blossomed, giving rise to the suite of projects allied to SETI – the Search for Extra-Terrestrial Intelligence.

SETI projects have mostly continued to focus on scanning the skies for alien transmissions. The global following of the search is immense: the non-profit organisation The SETI League have created a global network of amateur-built radio telescopes pointed skywards, watching and waiting. Similarly, the SETI@Home project invites internet users to contribute computer power to analysing radio-astronomy data for signs of communication. Truly, the worldwide scientific collaboration is commendable. And what has this global search turned up? Nothing. It seems, then, that we are alone.

But stop there! OK, we haven’t found any other intelligent life forms that are communicating on radio frequencies, but are we not perhaps jumping the gun a little? Would it not be equally as enlightening to find life at all on another planet, whether it is intelligent or not? It would certainly give a more complete picture of how we came to be here on Earth. Discovering the range of interstellar biology would provide a ‘bottom-up’ approach to searching for more advanced organisms and, ultimately, intelligence. The modern incarnation of the field of astrobiology is concerned more with this, with the active search for life and its repercussions in the universe, than the somewhat stay-at-home approach of SETI. Astrobiology today is a broad collaboration between astronomers, cosmologists, earth scientists, biologists, chemists and engineers, with over 30 research groups working on different approaches to understanding the place of life in time and space.

How do you go about finding life if it isn’t actively trying to communicate? The first problem is what exactly to define as life. There are as many as 60 different definitions of life, depending on your point of view – for example the widely used biological MERRINGS (movement, excretion, respiration, reproduction, irritability, nutrition, growth) system, which is little use in testing fossil organisms, or atypical life forms, or in fact, anything we find in space. Astrobiologists choose to use the short NASA definition as a starting point: ‘Life is a self-sustained chemical system capable of undergoing Darwinian evolution. Working from this basic definition gives broad scope for investigation of early life forms across the many light years of space.

The first step in our search for alien life is to understand how to get life in the first place. Tying intimately into studies of early life on Earth, palaeontologists, geologists and chemists work together to discover the timing, likely environment and mechanisms of the origin of life. There are intermediate states of life that would seem very strange to an observer today, but were essential in the development of life as we know it. A cell with a fundamentally different metabolism to today was likely to be a common sight on the early Earth. Understanding these life processes may be particularly important in identifying newly emergent life on other planets.

Secondly, once life is established, it is the job of microbiologists and earth scientists to understand the limits of that life. On Earth, living things were thought to only penetrate to about 10 cm deep in soils, 10 m deep in water, and to die out as altitude increased. Now, however, we find life of one form or another pretty much everywhere we look. It can survive at temperatures from -20 °C to around 120 °C; pressures of up to 1060 MPa, equivalent to 50 km beneath the Earth’s crust; and extremes of pH (both acid and alkali) and salinity. Such information is invaluable in the search for life elsewhere in the solar system and beyond, as it extends the range of so-called ‘habitable zones’, the area around a star where it is believed that life can exist. Depending on the size and age of a star, the nature of the planets surrounding it, and the range of conditions that life could tolerate, the size and position of habitable zones within other solar systems may be considerably different to that within our own.

Having established how and where life could exist outside Earth, the search can begin for likely habitable worlds. The most obvious place to start is our own solar system, and there are cases for potentially habitable environments either now or in the past on Mars, Venus, the Jovian moon Europa and the Saturnian moons Titan and Enceladus. These bodies, although almost certainly not harbouring intelligent, advanced life forms, are important short term destinations for astrobiological exploration, including investigation by remote or manned missions.

Astronomers and cosmologists are also occupied in finding habitable planets orbiting other stars. Extra-solar planet searches turned up the first results in 1996 and have, at the time of writing, located 452 bodies orbiting other stars in our galaxy. Most are the size of Jupiter or greater, because of resolution limitations, but a number of planets of little more than a few Earth-masses have been found. It is thought that the Earth-sized rocky planets, thought to be more habitable than larger bodies, greatly outnumber the larger planets in the galaxy.

So what happens if we do find life? Whether close or far, simple or advanced, are humans as a race equipped to deal with the knowledge that we are not alone? Needless to say, any astrobiological revolution will deeply affect our philosophical and social outlook, as well as transforming our scientific goals and our view of the universe. Currently, despite the fact that we are yet to find conclusive evidence of life anywhere, there are reams of UN legislation and quarantine regulations to ensure planetary protection in the event of living sample return. Far from allowing a District 9-esque cohabitation, any alien life, whether microscopic or advanced and gigantic, will never leave a sealed container in quarantine at the landing site.

Clearly there are many theoretical and practical obstacles to be overcome in our continuing search for life in the universe. But the field of astrobiology is yet young. The first man-made object was launched into space only 53 years ago. Even in the short period of human history, this is just a blink of an eye, and technology is moving faster every day. In the words of the brilliant departed astronomer Carl Sagan: ‘How lucky we are to live in this time, the first moment in human history when we are, in fact, visiting other worlds.’

Leila Battison, 2010