The Chemistry of Life
Some years ago I wrote a documentary planetarium presentation called Oceans in Space. It’s about the search for life on other worlds. We made a big deal in the show about how life needs three things to survive: water, warmth, and organic material (food). That’s fine as far as it goes, but the devil is in the details when it comes to figuring out what ELSE life needs to exist.
Of course the criteria describe Earth’s environment, but they also very generally cover a number of possible life-supporting places NOT on our planet. But, just because a place might satisfy all three criteria doesn’t guarantee that it supports (or even has) life. The solar system has a number of worlds that have water and warmth and even some organic material to serve as “food” for life forms. Mars has many places that were once inundated with water. Some of the smaller icy water-rich moons of the outer solar system, such as Enceladus and Europa, could also support microbial life (if nothing else). But, so far we’ve found no evidence for life in these places, and in fact, there are many places on Earth where life doesn’t thrive. What do they have in common?
According to researchers at the University of Arizona, who have been chosen by NASA to focus on the criteria that will guide our future searches for life on other worlds, it’s possible that those places may lack enough chemical elements to support life. So, while having water and warmth are a good start, if you don’t have the right chemical mix, it may be tough to start and sustain life.
Chemistry IS necessary for life, there’s no question about it. Last March I attended a seminar at Radcliffe Institute in Cambridge, Massachusetts, and the chemical origins of life were the main topic of conversation. (You can read the article I wrote about it here.) The message that “chemistry is life” was really forcefully brought home — and the details are fascinating.
The UA team (and its partners at the University of California, Riverside; University of California, Merced; Rice University and University of Illinois – Chicago, as well as NASA Goddard Space Flight Center, the Australian Centre for Astrobiology at the University of New South Wales and the National Autonomous University of Mexico, under the direction of Dr. Ariel Anbar, plans to refine the criteria to guide the search for life by characterizing life’s elemental requirements. In other words, they’ll delve into the necessary chemistry that life needs to form and thrive.
The team will explore the relationship between the elemental composition of organisms and their environments, the impact of planetary processes on the abundance of bioessential elements, and the effects of astrophysical processes on the abundance of life-supporting elements. This is an important area of study for astrobiology and I look forward to seeing results from their work as time goes by.