Category Archives: chemistry

cosmic chemistry, life

The Cosmic Garden of Eden

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Complex Molecules in Space

A few months ago I attended a day-long workshop about the chemical origins of life. The talks were aimed at tracing the chemicals that make up our very basic units (RNA, DNA) from first principles to the garden of biologic diversity we inhabit today. One of the talks focused on the finding the chemical precursors of life in interstellar dust clouds, which is really kind of a mind-blowing concept. But, when you think about it, since everything is chemical in origin, it makes sense that some of the chemicals that existed in the cloud our solar system formed in would also play a part in the origin of life.

There are organic molecules everywhere in space (and obviously here on Earth, but also at Jupiter, Saturn, and Titan. Researchers at Imperial College in London (England) have identified xantine and uracil — two very complex molecules needed to form RNA and DNA — in fragments of a meteorite that landed in Australia. The molecules didn’t come from Earth; they were present in whatever place the meteorite first formed. Which means that those molecules existed when the solar system formed, some 4.5 billion years ago. Eventually, rocks containing those molecules landed on Earth. It’s not much of a leap of the imagination to see that the ingredients for life could well have been delivered from space, and that we are really and truly “space stuff.”

What this should tell you is that the search for life in the universe isn’t really a search for little green men or cosmic omnisciences. It’s a journey that organic chemistry will lead, and all we have to do is study what it gives us.

chemistry, life

We Began in the Stars

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And We’ll Get Back There Again

For all you non-chemists in the crowd, did you know that life on Earth began with a sort of “starter yeast” of carbon-bearing compounds and other species of molecules that came from space? It’s true.

Naturally occurring ones Interstellar chemical labs contributed the iron that flows in our blood, the calcium that makes up our bones and the carbon-based molecules that make US up. And all that stuff came from stars that lived and died long ago. In the dying, they contributed elements built up over eons of time in stellar cores and atmospheres. Eventually those elements found their way to Earth, and into other chemical stewpots.

In a sense we are really the ashes of old stars, brought to life through massive and eons-long chemistry experiments. We began in stars like the ones that died to produce the Helix Nebula (left, a planetary nebula formed when a star like the Sun died) or the progenitor star that created the Crab Nebula (right) blew up more than 7,000 years ago. Near these two objects, clouds of gas and dust are scattering the chemical precursors of life. Someday perhaps they’ll combine to create new life forms.

Some 5 billion years from NOW, our Sun will start to expand and engulf the inner planets. That means that Earth (and by extension) all life upon it, will be vaporized; in essence, returned to the gas and dust from which we came. All that we were, plus all that the Sun will exhale in its dying days, will rush out to space to provide fodder for yet MORE new life, should there be places where it can form. So, while I’m not a religious person, I do find it interesting that in an astronomical sense, we are truly ashes to ashes, and dust to dust. We’ve come from space and we’ll be headed back, one way or another.