Monday, March 30, 2009

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.

Saturday, March 7, 2009

The Search for Extraterrestrial Life

NASA's Kepler mission successfully launched into space from Cape Canaveral aboard a Delta II rocket on Friday, March 6, 2009. According to NASA, Kepler is designed to find the first Earth-size planets with water – essential for life as we know it to develop.

The first planets that Kepler will explore are expected to be the "hot Jupiters" -- gas giants that circle close and fast around their stars. NASA's Hubble and Spitzer space telescopes will be able to follow up with these planets and learn more about their atmospheres. Neptune-size planets will most likely be found next, followed by rocky ones as small as Earth. The true Earth analogs -- Earth-sized planets orbiting stars like our sun at distances where surface water, and possibly life, could exist -- would take at least three years to discover and confirm. Ground-based telescopes also will contribute to the mission by verifying some of the finds.

NASA says that in the end, Kepler will give us our first look at the frequency of Earth-size planets in our Milky Way galaxy, as well as the frequency of Earth-size planets that could theoretically be habitable. According to NASA, "Even if we find no planets like Earth, that by itself would be profound. It would indicate that we are probably alone in the galaxy."

%%%%%

In December 2000, the research vessel Atlantis, a deep submersible, found an entirely new type of hydrothermal vent field, where active chimneys were emitting water heated to a relatively cool 100°F (40°C) to 170°F (80°C). They called the field "Lost City." The heat resulted from a chemical reaction between water and a subcrustal rock called peridotite. When the alkaline solution emerged, calcium carbonate crystallized, building shapes like stalagmites.

Until Lost City was found, most known deep-sea vents sprang from young, volcanically active regions such as mid-ocean ridges, where sulfide chimneys expel water as hot as 760°F (400°C). Yet Lost City's formations lie nine miles from the Mid-Atlantic Ridge on 1.5-million-year-old rock in an alkaline environment that may be similar to that of early Earth.

More fascinating still, the recent study of deep-sea vents reveals that surrounding life is based on chemosynthesis, the conversion of chemical energy into biomass, rather than photosynthesis, which converts light into biomass. Such a discovery broadens the search for life in the universe.

%%%%%

The most enduring and compelling question for man is, "Are we alone in the universe?" By that, we mean are there others out there like us? That's why the term extraterrestrial life is usually qualified by "intelligent life as we know it." That's a problem, because intelligent extraterrestrial life may be nothing like what we know.

As it happens, there is no universally agreed upon definition of intelligence. We tend to think of human intelligence as involving higher order reasoning -- a cognitive ability that lets us learn from, adapt to, and deal effectively with our environment. We are predisposed, one might say, prejudiced, to see this ability emanating from an organ -- the brain -- in an individual body. Seth Shostak , a senior astronomer at the SETI Institute, when asked what extraterrestrials might look like said, “They'll be bigger than a breadbox and probably smaller than an elephant, would be my guess.” Think ET.

%%%%%

Intelligent life need not take the form we envision, however. Extraterrestrial intelligence may exist in a distributed form. It's interesting to note, for example, that SETI itself is using a form of distributed intelligence to explore the cosmos for extraterrestrial intelligence. SETI@home is a scientific experiment that uses Internet-connected computers in the search. Anyone with a computer can participate by running a free program that downloads and analyzes radio telescope data.

We have life here on earth that defies our preconceived notions of what a living organism should look like. Take the sea jelly, or more commonly, the jellyfish, for example. It has no specialized digestive, respiratory, or circulatory systems. Its mouth is also its anus. It has no eyes. It has no brain (except for the Box Jellyfish, which has four separate brains) and no central nervous system, but rather a loose network of nerves, located in the epidermis, which is called a "nerve net." A jellyfish detects various stimuli, including the touch of other animals via this nerve net, which then transmits impulses both throughout the nerve net and around a circular nerve ring to other nerve cells. Jellyfish seem to sense when their species is in danger and reproduce exponentially. One species of jelly, the Turritopsis nutricula, is effectively immortal. It can revert completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage. It does this through the cell development process of transdifferentiation. Theoretically, this cycle can repeat indefinitely, rendering the T. nutricula biologically immortal.

%%%%%

In a future post I will discuss the idea of a life form connected not by tissue, but by a cosmic distributed intelligence that incorporates components on earth.

Monday, March 2, 2009

It's my birthday!

Today is my birthday. I was born on this day in 1938, at approximately 4 o’clock in the morning. That’s seventy-one years and about five hours ago. Time flies. Or does it?

Time actually does nothing. It doesn’t fly, it doesn’t pass, it doesn’t heal, and we know it doesn’t wait. So what the heck good is it?

Man invented the concept of time in an effort to order his chaotic world. A world in which light turned to darkness and back again to light, trees turned from green to varying shades of yellow and orange and brown and then became leafless, only to return to their state of greenness once again, a whole myriad of flora and fauna went through similar and even more bizarre changes, all beyond the understanding of earth’s early human inhabitants. And most unsettling of all, humans noticed changes in themselves; their hair turned from black to grey or white, backs became stooped, hands and fingers crooked, eyes filmy and sight blurred, and then, one day, they could not stand, or eat, or breathe and a darkness fell that never again turned to light. Why?

Here’s what I will tell you – it isn’t “getting old” that ultimately kills us. What kills us are the collective changes that occur in our body’s systems; the wear and tear on bones that make up our skeletal system, the deterioration of our musculature system due to changes in our hormonal balance as the need for reproductive behavior declines, our skin wearing out as the elements take their toll, our arteries filling with plaque, causing our circulatory system to work harder to distribute blood, raising our blood pressure, and so on, and on, until…well, you know. And that’s why.

The fact of our human mortality is the single most compelling reason for our invention of, and subsequent misunderstanding of time. It isn’t time -- “getting old” -- that kills us. Aging is a construct (a psychological invention) used to explain the phenomena that in fact, occur to cause our physical death. Because life is so important to us, we have invented a system to gauge when it is likely to cease. Ultimately the system progressed from a vague idea of, “Many moons has he served the tribe,” to, “The chief is eighty years old,” where we compare the occurrence of the earth’s position relative to the sun with a mechanical device we call a clock. This is psychological time. It has no intrinsic existence. It exists only in our thoughts.

Because we are so inextricably tied to the concept of time, which we ourselves invented, and because we see the passing of time as so central to our own existence, we cannot think of a universe without time, “To every thing there is a season, and a time to every purpose under the heaven: A time to be born, and a time to die.”

But the universe was here before us and it will be here after us, and although there are those who believe in a beginning of time -- a “Creation” for the religious, and a “Big Bang” for cosmologists, there is really no reason to believe that the universe, apart from our own existence, had a beginning, or will have an end.

See "The Universe and all that Stuff" for a related post.