Life Unexpected

There are creatures living around thermal vents in the deep ocean that function without light and near vent water that would seem too hot and toxic to support life. Among them are worms, clams, mussels, mollusks, octopuses, fish, crabs and other crustaceans.

To date, more than 500 new species have been found at vent sites throughout the world's oceans.

Some of the strangest are two kinds of vent worms: the tubeworm (Riftia pachyptila), which can grow to 6 feet tall, yet has no eyes, mouth, stomach or gut, and the hairy, 5-inch Pompeii worm (Alvinella pompejana). These life forms and others live in temperatures reaching 400C (760F). If life can thrive in this superheated environment, would it be possible for microorganisms on meteors to survive the fiery entry into earth's orbit?

On September 28, 1969, a meteorite shower fell around the small town of Murchison, Australia. Witnesses saw a bright orange ball with a dull orange tail traveling across the sky trailing blue smoke. They heard a sonic boom and hundreds of small meteorite fragments fell around Murchison. The largest fragment was later found to weigh 7 kg. A farmer found that one fragment had penetrated the roof of his hay shed.

The Murchison meteorite fragments have been an important source for the study of organic compounds, the birth of our solar system, and the origins of life.

A NASA astrophysicist, Richard Hoover, reportedly found fossilized remains of complex biological structures within the Murchison meteorites. They could be extraterrestrial microorganisms that existed during the last 4.4 billion years.

Is it possible for microorganisms to hitch a ride to earth on meteorites? A NASA-funded research team found the first organic molecules thought to be of Martian origin -- several mineral features characteristic of biological activity, and possible microscopic fossils of primitive, bacteria-like organisms inside an ancient Martian rock that fell to Earth as a meteorite.

The possibility that life first came to earth and indeed, was distributed throughout the universe by ejecta blasted from planets bombarded by huge meteors has spawned a theory of interstellar life variously called "panspermia," or "transpermia."

The prospect of "life spores" traveling through space to seed planets like earth is intriguing, but is it a viable hypothesis? In an earlier post, I discussed the role of cyanobacteria in creating an environment conducive to life on earth. Without this particular bacterium, we would not exist. How did it get here?

Did cyanobacteria come to earth riding a meteor?

More on this in future posts.