Comets May Have Seeded Life On Earth
March 6, 2013

Could Life On Earth Have Come From Outer Space?

John P. Millis, Ph.D. for — Your Universe Online

Where did we come from? It is the question that has faced scientists, theologians and philosophers for millennia. And even in this age of technology, we have yet to stumble across the answer.

One of the challenges is that it seems that living cells are difficult to make. Not only are they relatively complex structures, but also putting them together in such a way as to put into motion a metabolic system that can take external resources and convert them into energy is an even more monumental task.

To date, we have yet to successfully create a living cell in a lab from component material. The only way that we can proliferate life is to “grow” it from already living cells. Genesis remains elusive.

Since it is clear that a certain density of organic building blocks, mixed with enough energy, is necessary, many scientists have championed the idea that life must have begun in the oceans. Explaining how complex organic molecules otherwise arise is unclear.

But a new study may be changing all of that.

Life In Space

In recent years, some researchers have proposed that life may have originated beyond Earth´s canopy. On the surface this notion seems unlikely. Since, in the icy cold vacuum of space, compounds don´t have much opportunity to mix. Furthermore, the low thermal energy of the environment makes the evolution of more advanced molecules difficult.

However, previous study of meteorites has indicated that organic compounds, although rather simple, have formed in space. These works left the door open to the possibility that life, or at least the basic organic material, may have arrived from the heavens.

The problem, however, has long been the formation of more complex organic compounds. Now, a team led by UC Berkeley chemist Richard Mathies, with Seol Kim and Ralf Kaiser of the University of Hawaii, has found that the basic organic compounds found in previous studies could give rise to more complex molecules from the very environment of space once thought to be the roadblock to life.

Simulating Space

In order to simulate the conditions in outer space, the researchers created an ultra-high vacuum chamber that was cooled to 10 kelvin. The University of Hawaii team then targeted a “icy snowball” composed of carbon dioxide, ammonia and various hydrocarbons such as methane, ethane and propane with a very high-energy electron beam.

This system simulated what a comet, or other icy body, might experience as it interacted with very high-energy cosmic rays which stream throughout the cosmos.

The result was that the compounds reacted with the electrons and began to form more complex organic molecules. Using a highly sensitive organic analyzer Dr. Mathies and colleague Amanda Stockton, also of UC Berkley, were able to then isolate nine different amino acids and at least two dipeptides — all necessary building blocks of life on Earth.

Dr. Mathies noted, “It is fascinating to consider that the most basic biochemical building blocks that led to life on Earth may well have had an extraterrestrial origin.”

This work is detailed in the March 10 print issue of The Astrophysical Journal.