A New "Drake" Equation for Potential of Life
Written by Nancy Atkinson
An image showing microbes living in sandstone in Antarctica (credit: C Cockell)
The famed Drake equation estimates the number of technologically advanced civilizations that might exist in our Galaxy. But is there a way to mathematically quantify a habitat’s potential for hosting life?
“At present, there is no easy way of directly comparing the suitability of different environments as a habitat for life" said Dr. Axel Hagermann, who is proposing a method to find a "habitability index" at the European Planetary Science Congress.
"The classical definition of a habitable environment," said Hagermann, "is one that has the presence of a solvent, for example water, availability of the raw materials for life, clement conditions and some kind of energy source, so we tend to define a place as ‘habitable’ if it falls into the area where these criteria overlap on a Venn diagram. This is fine for specific instances, but it gives us no quantifiable way of comparing exactly how habitable one environment is in comparison with another, which I think is very important.”
Hagermann and colleague Charles Cockell have the ambitious aim of developing a single, normalized indicator of habitability, mathematically describing all the variables of each of the four habitability criteria. Initially, they are focusing on describing all the qualities of an energy source that may help or hinder the development of life.
“Electromagnetic radiation may seem simple to quantify in terms of wavelengths and joules, but there are many things to consider in terms of habitability," Hagermann said. "For instance, while visible and infrared wavelengths are important for life and processes such as photosynthesis, ultraviolet and X-rays are harmful. If you can imagine a planet with a thin atmosphere that lets through some of this harmful radiation, there must be a certain depth in the soil where the ‘bad’ radiation has been absorbed but the ‘good’ radiation can penetrate. We are looking to be able to define this optimal habitable region in a way that we can say that it is ‘as habitable’ or ‘less habitable’ than a desert in Morocco, for example.”
The pair will be presenting their initial study and asking for feedback from colleagues at the European Planetary Science Congress. “There may be good reasons why such a habitability index is not going to work and, with so many variables to consider, it is not going to be an easy task to develop. However, this kind of index has the potential to be an invaluable tool as we begin to understand more about the conditions needed for life to evolve and we find more locations in our Solar System and beyond that might be habitable.”
Source: Europlanet
Filed under: Astrobiology
Tags: Astrobiology, Drake EquationRelated stories on Universe Today
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September 16th, 2009 at 5:38 pm
Yay! Even more terms for everyone to argue over.
September 16th, 2009 at 6:41 pm
There's a typo in the 2nd line, at 2nd (or is that 3rd?) paragraph: climate, not "clement".
September 16th, 2009 at 6:48 pm
Hmmmm – It seems a bit too ambitious if you ask me. The fact is that there ARE so many variables (as they have acknowledged), and these can combine in unexpected ways. Even without knowing the intimate details of their proposed methods, I still can't see how it could ever assign anything more that a very rough 'index of habitability', and hence I question it's usefulness.
Still, worth having a think about I guess.
September 16th, 2009 at 6:52 pm
"IVAN3MAN Says:
September 16th, 2009 at 6:41 pm
"There's a typo in the 2nd line, at 2nd (or is that 3rd?) paragraph: climate, not "clement"."
No, actually there is not. 'Clement' is a word – it is the antonym of 'inclement'.
clem·ent (klmnt)
adj.
1. Inclined to be lenient or merciful.
2. Mild: clement weather.
September 16th, 2009 at 7:18 pm
Err… my bad. That will teach me to check with the bloody dictionary before sounding off…
clement — –adjective 1. mild or merciful in disposition or character; lenient; compassionate . 2. (of the weather) mild or temperate; pleasant. [Origin: Middle English, from Latin clemens, gentle.]
My apologies, Nancy.
September 16th, 2009 at 7:18 pm
I feel a Rumsfeldian quotation coming on…
September 16th, 2009 at 7:29 pm
@ Astrofiend,
Yes, thank you! Initially, I was thinking of the name Clement, but realized that it's an adjective after checking with the dictionary.
September 16th, 2009 at 9:18 pm
Such drake-style equations are easy to churn out, just think "What does [scenario] depend on?", list them as a probability, and sort properly.
"[A]s we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns — the ones we don't know we don't know."
That made my brain bleed v_v
September 17th, 2009 at 4:06 am
This proposal decomposes into two areas, of comparison (which would be both valuable and easy) and of discovery (which would be valuable but, perhaps, easier after actually finding some other biospheres to get at the possibilities). Not unlike the Drake equation itself.
So FWIW we can put up the following model:
Nm = Rp x ft x fh x fo x Lm;
Nm = number of valid models
Rp = rate of model proposals
ft = fraction of testable proposals
fh = fraction of those tests where habitability actually exist
fo = fraction of habitable biospheres actually observed
Lm = lifetime of valid models.
Obviously the lifetime of valid models will -> oo if actually tested, but one can have some concern for the probability of this proposal ever achieving the neighborhood of ~ 1 valid model.
For a while there I thought you were able to joke about your obsessive behavior. That will teach me to suspend my bloody judgment. (o.O)
September 17th, 2009 at 4:18 am
D'oh and d'oh!!
1. "if actually tested" – if biospheres are actually observed. Nm is number of "alive" valid models…
2. IVAN3MAN did joke, I guess I put that as harshly as I could. (Another lesson, I'm sure.) I'll amend that to "were joking about".
September 17th, 2009 at 5:36 am
When I first came across the Drake equation I thought, 'Wow, this could be really interesting'. But as I've grown older I'm more of teh opinion that it's almost a waste of time even discussing it. Sure we've more or less worked out the average start formation, discovered a few big [planets around a few good stars, and possibly just about worked out that a very few planets exist within some stars eco-systems. The rest of Drake's Equation are unknown and until we find unequivical evidence of life speculation is just that, speculation. All very nice sat round with a snifter of brandy debating this and that about possibilities of life here or there but, from my point of view, pointless. I'm all for blue-sky thinking and BIG SCIENCE experiments that push the envelope but we're dealing with so many unknowns/unknowables here that we're perhaps wasting our time. [at present at least]
September 17th, 2009 at 1:11 pm
And as they eavesdrop on this conversation, the Rock People of Epsilon Zeta 5 say: "Hah! Pompous carbon-based lifeforms…"
September 18th, 2009 at 9:00 am
When did this site become so disinterested with the science we signed up for and render itself a bunch of gossipy old hens obsessed with spelling and grammar?
Woops! There's a scratch in the vinyl – someone put a quarter on it……… OK – maybe a nickel….