Date: January 22, 2009
Title: What is Astrobiology — with Dr. Allie Ford
Podcaster: Brains Matter
Description: In this interview, The Ordinary Guy talks to Dr. Allie Ford, an astronomer who is an expert in astrobiology, about the possibilities of life elsewhere in the universe. What is fundamentally required for life to evolve? What types of life could there be?
Bio: The Brains Matter podcast has been producing and communicating science stories and interviews since September 2006. The show is based out of Melbourne, Australia, and takes an everyday person’s perspective of science in easy-to-understand language.
Today’s Sponsor: American Astronomical Society
Transcript:
G’day everyone, I’m The Ordinary Guy, coming to you from Melbourne in Australia, and welcome to a very special episode of Brains Matter.
Today we have a special shortened episode for the 365 Days of Astronomy – you can find out more details of the 365 Days of Astronomy at www.365daysofastronomy.org, and about the International Year of Astronomy at www.astronomy2009.org.
On today’s show, I have an extract of an interview with Dr Allie Ford from Monash University, on the topic of Astrobiology. If you want to hear the full two-part interview, please head over to the Brains Matter website at http://www.brainsmatter.com
OG: Today weʼre going to be talking about astrobiology, and just thinking about the title itself – astro sounds like something from outer space, and biology sounds like life, so are we talking about life from outer space?
AF: Thatʼs a fairly good way of looking at it. We havenʼt obviously found life from outer space yet, but itʼs about the search for life. SETI is certainly a part of astrobiology – itʼs one component. Astrobiology is a wide-ranging field, it includes aspects of everything from computing and IT, artificial intelligence, through to biology, chemistry, physics, philosophyof science, maths, geosciences – itʼs got bits of everything.
Weʼve found amino acids throughout the universe, weʼve found them in interstellar clouds, in meteorites, and just generally in other parts of the solar system and in other parts of space.
So amino acids are the building blocks of protein, which are very important to life – so if we can find them elsewhere, and thereʼs some way of taking the magic step to living systems – the ingredients are all out there.
OG: So are we making a bit of an assumption that an amino acid could or will lead to life? I guess what Iʼm asking is that just because thereʼs an amino acid, does that mean that there will eventually be life there given enough time?
AF: Thatʼs a really good point because the thing that weʼre missing in our study of the evolution of life is that step from inanimate objects into living systems. Weʼve never managed to reproduce that transition.
OG: So at what point do we consider something to be life? So if we have amino acids and they bond together and then they form DNA – Iʼm not a biologist so forgive me if I ask a silly question – but is DNA itself life? Or does it have to be a cell? Iʼm just trying to understand at what point do we consider an “entity” to be life?
AF: Thatʼs a whole separate question in itself and thatʼs a whole area of philosophy and various other things about that – it all comes down to your definition of life. We would probably define life as a self-replicating system which uses energy from its surroundings and builds that into itself – so metabolism.
OG: You mentioned that they found amino acids elsewhere in the universe – how complex are these amino acids? Are they very simple or are they actually quite complicated strands like you might have found in the Urey-Miller experiment?
AF: Well, living systems on Earth have about 20 different amino acids that weʼve actually found, and I think about 18 of those have actually been detected in space, in varying ranges of complexity.
OG: So does that mean finding these particular amino acids in particular areas of space – they currently exist in their current forms in whatever environmental surroundings they are in, and they wonʼt evolve any further because they donʼt have conditions conducive to life?
AF: We donʼt know what those conditions are. As I said before, we havenʼt managed to replicate that jump from amino acids and sugars and the building blocks of all our living systems into something that is alive… so we donʼt know exactly what conditions you need to make that happen – so we canʼt really say whether or not they will …. or they wonʼt… at this stage!
OG: I guess one perspective you could take on it is if these amino acids are on a planet, there is probably a more likely chance that they will evolve into something if there were conditions like prehistoric earth for example, compared to if they were in an interstellar gas cloud.
AF: Yeah, well there are certain conditions you probably do need to enable life to develop certainly any level of complexity – things like protection from radiation, which on earth we have in the form of the atmosphere and the oceans.
A solvent – water seems to be the thing that is most likely to be the best solvent for life, but there are other solvents in the universe. So by a solvent we mean a liquid which can dissolve other molecules and allow them to react together. And the third thing we need is a source of energy. On Earth the main one we would use would be the sun although theyʼve found living systems near black smokers and hydrothermal vents, where there is no sunlight, and theyʼve evolved to use the energy stored within the Earth.
OG: But effectively thatʼs heat energy anyway.
AF: Yes, energy in some kind – heat is a form of energy.
OG: In all the books and stories Iʼve heard and read about life in other places in the universe, they always talk about water and carbon, and it makes sense for us on Earth because thatʼs the paradigm we are used to. Every single living entity on Earth is carbon based – is that a valid assumption to make? Like you read in some science fiction books for example that there might be silicon based life?
AF: We canʼt say itʼs a completely invalid assumption because we donʼt have any other samples to base it on, and it certainly is valid in the case on Earth because every living system we have is carbon based and water based, but scientifically there seems to be fairly good grounding for those substances to be fairly prominent.
OG: But thereʼs nothing from a chemistry perspective to say “you cannot have a silicon based life form” – or is there?
AF: Thereʼs nothing that definitely says you canʼt, but it would be quite difficult with our understanding, because when you breathe, you inhale oxygen, and the sugars and amino acids in our bodies react and produce carbon which we respire in the form of carbon dioxide, which is a gas. So we can breathe it out fairly easily. If youʼre a silicon based organism, and you inspire oxygen, when you breathe out, you
breathe out silicon dioxides, which tend to be solid – so sand is a good example – so thereʼs a lot of complexity with how you could remove that from your system and what kind of biology youʼd need to be able to handle that, and energy wise, it probably wouldnʼt be very efficient – unless thereʼs a whole branch of chemistry that we just donʼt understand there.
I hope you enjoyed hearing about astrobiology. For the full interview and other topics,
please go to http://www.brainsmatter.com.
I hope you continue to enjoy the 365 days of astronomy – I know I certainly will! I’ll leave you with a quote from Sir Arthur Eddington – “We are bits of stellar matter that got cold by accident, bits of a star gone wrong”
Bye for now!
365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.
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Fascinating!
Dear Ordinary Guy,
Great interview – you where asking all the right questions! I was very fascinated by the statement that there maybe other solvents available in the cosmos that will support life. I would like to know what those maybe!
Stay ordinary for the rest of us!
Hi Richard, I’m glad you enjoyed the podcast!
Some of the alternate solvents which are relatively common in other parts of the Solar System (and in some cases, in other parts of the Universe) are ethane, methane and ammonia. The difficulties with these (as we see it) are that they are liquids at much lower temperatures than water is, which means that any chemical reactions that take place within those solvents are likely to be much slower.
Another difference is that of the range over which the solvents are liquid. While ethane is liquid over 94Celcius (or Kelvin), methane and ammonia are liquid over smaller ranges (just 18C in the case of methane) which means that any life in those systems would be at threat if there were any significant temperature variations – 18C is greater than the change between day and night on Earth sometimes!).
Water also has other advantages over the other solvents though – it has a very high specific heat capacity, meaning that it acts as a temperature buffer, soaking up large amounts of energy before it changes temperature itself (hence it is used in a lot of radiators).
Water is a polar solvent, which could be important for the formation of membranes, and also plays a role in the fact that ice floats. This could potentially have saved some species during previous ice ages by preventing the oceans from freezing completely.
These problems could potentially be overcome by novel conditions or solutions beyond our current thinking – but until we find something living in a different solvent, it seems that water is the ideal solvent for life.
I think some of this was discussed in the full interview on Brains Matter so do check it out.
Thanks for listening!
…and that is going to give me the content I need for another Planetary Radio Q and A segment. Thanks, Brains Matter!
Thanks for your simple to the point answer on solvents. Much to ponder here……
Very Good Podcast.