Archive for the ‘biology’ Tag

Life in the Universe IV   2 comments

Wherever life is, you will most likely find water or some other liquid.

Wherever life is, you will most likely find water or some other liquid.

This is a continuation of a series of posts.  Each is designed to be understandable without reading the others; they do build off each other, however, so check them out starting with Part I.  In the last post on this topic, I hope I got across how little we know of life’s beginnings.  This planet we live on hosts the only life we know of thus far…in the whole universe!  Does that mean we are most likely alone?  Not really.  This and the next post will look at the possibilities for life elsewhere.

Water is a good thing, but energy is also necessary for life; here in the form of geothermal heat in Yellowstone National Park.

Water is a good thing for life, but energy is also necessary; here in the form of geothermal heat in Yellowstone National Park.

It must be said that our ignorance of what the universe offers in terms of life beyond our solar system is profound.  Actually, I should not be so negative, because over the past decade or so we have found out much more about our universe’s capability to host life than we knew before.  This new knowledge has come in the form of the discovery of planets orbiting other star systems, along with the discovery of microscopic life in places we never thought could host life.

There is something I should mention before going further.  Scientists who study this sort of thing, called astrobiologists, do not expect to find any living thing out there that is visible without the aid of a microscope.  That’s because the conditions that are favorable for microscopic life (bacteria, etc.) are much broader in scope than those favorable for multi-cellular (big) life.  In addition, more complex life requires a much longer period of time before it can take hold, as opposed to the shorter time required for simple one-celled life to evolve.  But one thing is for certain: once we find microscopic life anywhere outside Earth, the stage is set for discovering much more complex forms.

Symmetry in nature comes in all shapes and sizes.

Symmetry in nature comes in all shapes and sizes.

Where We’ve Been

Humans have been probing the planets we share this sun with for a number of years now.  The first exploration outside of Earth orbit happened in 1962, when Mariner 2 flew close to the thick, acid-laced cloud-tops of Venus.  Then came the Apollo era, when the United States sent astronauts to the Moon and Russia managed to land a few craft on hostile Venus.  We also probed Mercury with a later Mariner mission.

The twin Voyager probes, launched in the late 1970s, were our first foray to the outer planets.  Voyager 1 showed us incredibly detailed close-up views of the gas giants Jupiter and Saturn.  Voyager 2 flew by Uranus and Neptune as well (still the only time we’ve visited those distant planets).  I recall seeing those first images of Jupiter’s clouds and Saturn’s rings in detail.  I was in High School, and the details were was truly blown away.  And I wasn’t the only one.

I normally only use my own images in this blog, but this painting is so realistic I couldn't resist.  Click image to go to source page.

I normally only use my own images in this blog, but this painting is so realistic I couldn’t resist. Click image to go to source page.

The Voyager probes are now the furthest from home that anything made by humans has ever traveled, and they win this honor by a mile!  Both are well over 100 times as far from the Earth as we are from the Sun.  They are also traveling by far faster than anything humans have ever built.  Soon Voyager 1 will arrive at the Heliopause, which is the spherical boundary around our Sun where the solar wind ceases to be the major influence, and instead galactic forces take hold.  In other words, our little travelers are about to leave our star’s neighborhood and forge a path out to the great beyond, the Milky Way Galaxy.

The U.S. has been the de facto explorer of the Moon and Mars, along with the outer planets, while the Russians picked the most hostile rocky planet on which to land a probe – Venus.  The European Space Agency has also been active more recently, designing the probe that landed on Saturn’s moon Titan.  While Mars garners the most attention, with its rovers and orbiting observatory, two U.S. probes are busy elsewhere.  Messenger is finishing up its mission at Mercury and Cassini continues to orbit Saturn and its zoo of moons.

The full moon rises on the North Rim of Grand Canyon, as Orion, Jupiter and company shine above.

The full moon rises on the North Rim of Grand Canyon, as Orion, Jupiter and company shine above.

Life on Mars?

In the 1970s we landed for the first time on Mars.  The lander was called Viking.  Along with incredible photography, the non-mobile lander dug up a small sample of soil and analyzed it for life.  Although it looked initially like the results might turn out positive, the soil was found to be completely hostile to life.  Since then, a series of Martian orbiters and rovers have found abundant evidence of water on Mars.  The only problem?  This water appears to have last flowed billions of years ago.  (Intriguingly, there is some evidence of periodic eruptions of liquid water from below ground, even recently.)  We have yet to find fossil evidence of past life on Mars, and the planet’s current condition appears to be as hostile to life as we ever thought.

An eclipse of the sun is one of the more humbling natural spectacles.

An eclipse of the sun is one of the more humbling natural spectacles.

Life Beyond Mars: It’s the Moons

Since both Venus and Mercury are much too hot to hold liquid water, even in the distant past, the next good place (beyond Mars) to look for life are the many moons of Jupiter and Saturn.  Europa, one of Jupiter’s moons, has been known for years to have a liquid ocean beneath a thick ice cap.  The moon is heated by enormous tidal forces created by the nearby gas giant, so this probably means that hot vents discharge into the sea.  On Earth, undersea hot springs host entire ecoysystems, so it stands to reason that Europa could  hide similarly-powered concentrations of life clustered around hot vents beneath its ice cap.  Also, Enceladus, a moon of Saturn that also has a subsurface ocean, represents an excellent habitat for life.

Mount Rainier and the night sky above Eunice Lake.

Mount Rainier and the night sky above Eunice Lake.

Although other moons around Jupiter and Saturn are thought to contain liquid or partly liquid interiors, arguably the most intriguing place to search for life is Titan.  Titan, orbiting Saturn, is the Solar System’s second largest moon.  It’s larger than Mercury and not much smaller than Mars.  There is a lot of methane on Titan, much of it liquid because of the frigid temperatures.  In fact, methane on Titan might serve the same role as water does on Earth.  We have observed features like river valleys and lakes on Titan, but instead of being filled with water they are filled with liquid methane.

The relative sizes of Earth, Mars and selected moons in the solar system.

The relative sizes of Earth, Mars and selected moons in the solar system.  Click on image to go to website where the author of this image, Abel Mendez, is sourced.

Why is this interesting for life?  Because prior to the emergence of oxygen, Earth was a planet rich in methane as well.  Early life on Earth relied on methane not oxygen, and in fact, these organisms are still around.  There is an enormous community of micro-organisms (methanogens) living just beneath the sea floor today.  In fact the methane they produce has been stored in ice formations that could, because of global warming, erupt and release into the atmosphere, greatly accelerating global warming.  Many scientists think Titan could be revealed to operate much as Earth did billions of years ago, with microscopic life very similar to those early Earth days.

The fact is, although we have made great strides in understanding how likely it is to find life within this solar system of ours, we are just now scratching the surface.  Life on Mars has by no means been ruled out, and the moons of the outer solar system are just now being examined.  It will take a very sophisticated effort to look for life in Europa’s subterranean ocean, or across the huge and distant moon Titan, or on Enceladus.  But even the discovery of a community of extremophiles (micro-organisms adapted to extreme environments) on one of these relatively nearby bodies would be a watershed moment.  It would tell us that we are not alone in our neighborhood, and that life has likely gotten started in countless locations across the universe.

Next up: the incredibly diverse zoo of planets orbiting other stars.

Evening falls on the Columbia River, where two explorers passed on their way to discovery.  It's now quiet, and the frontier has moved on.

Evening falls on the Columbia River, where two explorers passed on their way to discovery. It’s now quiet, and the frontier has moved on.

Life in the Universe III   13 comments

Isn't it natural to believe that our Creator is from on high?

Isn’t it natural to believe that our Creator is from on high?

At one time I thought God created everything, but I can’t remember ever truly believing it was during 6 very busy days.  I do remember giving serious consideration to whether or not Purgatory would be an interesting place to stop before going to Heaven, even if there was a small chance I could be sent instead to Hell by mistake.  Then soon after I seriously began studying science, I put my inner religious beliefs into a little box and went on, unencumbered, to feed my curiosity.  I didn’t throw my beliefs away.  I believe that as you go through life, you should try not to throw things away unless you really need to.  We already lose too much as we grow older.

Buddhists create a spiritual atmosphere with these: Laos.

Buddhists create a spiritual atmosphere with these: Laos.

I learned that it’s likely life emerged from non-life by a trick of chemistry, and that was that.  I had bigger fish to fry – how the Earth and other planets formed.  I knew scientists didn’t really know exactly how life began, but I figured they would find out soon enough.  It wasn’t for me an important question for a long time.

(An aside: I sometimes wonder whether I would have become obsessed with life’s origins, had I went further in the direction I explored my senior year in college.  I was good at chemistry in college, and I took a class called Thermodynamic Geochemistry, which sounds a lot tougher than it actually was – but it would have gotten very tough if I had pursued it.)

Probably the world's oldest religion.

Probably the world’s oldest religion: Judaism.

Meanwhile, for the scientists who work on it, the origin of life has been an unusually thorny problem.  There have been many side-tracks along the way, from primordial soup to deep sea vents to extra-terrestrial origins (panspermia).

Earth was a barren place before life, and water only appeared in mirages (if anyone were there to see them).

Earth was a barren place before life, and water only appeared in mirages (if anyone were there to see them).

One of the first environments thought to be the cradle for life: shallows of the sea.

One of the first environments thought to be the cradle of life: shallows of the sea.

 

The State of Our Knowledge of Life’s Origin

We don’t really know what kind of environment hosted the first life.  It could have been in a thermal area, or in ice, or even in solid rock.  It could have been on Mars.  But wherever it was, water very likely was the dominant substance surrounding the primitive beings.

The clear pools at Semuc Champey in the Guatemalan highlands invite a cooling swim.

The clear pools at Semuc Champey in the Guatemalan highlands invite a cooling swim.

Perhaps a non-living compound underwent some chemical transformation into RNA.  RNA can do the work of forming proteins (as it’s doing right now inside you) but it can also reproduce, like DNA.   Then it’s just a matter of finding itself in the right place at the right time (pre-cells), to be put to work in an entirely novel way in something we would now call alive.

Clay is thought to be a likely place for pre-living chemistry to have taken place.

Clay is thought to be a likely place for pre-living chemistry to have taken place.

Or perhaps non-living structures similar to our body’s cells first started to form in high-energy environments (like deep sea vents) and they began to process energy (it’s thermodynamically favorable).  Then they began to reproduce (via RNA).  Most scientists believe that RNA is an important key.

Life was born because chemical compounds were formed at great odds.  Here salt crystals form naturally when pools evaporate in the desert.

Life was born because chemical compounds formed at great odds. Salt crystals form naturally when pools evaporate in the desert.

Perhaps you know of Craig Venter.  He’s the guy who led the team who first decoded the human genome.  He’s at work now on trying to create a living organism with no biological parents (actually a computer takes the parents’ place).  Many believe that creating life ourselves is necessary before we can understand how it arose.  As Richard Feynman once said, “What I cannot create, I do not understand”.

Active volcanoes (this one in Indonesia) could have easily provided a spark for the origin of life.

Active volcanoes (this one in Indonesia) could have easily provided a spark for the origin of life.

You can see there is some uncertainty here, and every good chemist knows these transformations are not at all easy.  But it happened.  Stuff happens after all, and given a lot of time and the right environment, perhaps life has been emerging  everywhere, throughout the history of the universe.  So what if we can’t explain the moment of life’s creation.  Does it matter?

Did life come from another planet to seed Earth's lifeless oceans?

Did life come from another planet to seed Earth’s lifeless oceans?

I tend to think that life in this solar system evolved on Earth first, but I wouldn’t bee too surprised if it started on Mars first and was transported to Earth riding on a meteor.  I also believe that this question: how did life start, is an important one.  I think it will take us a big step forward in figuring out how life emerged in the universe.  How we got here is one thing, but it will take much more insight to discover why we are here.

This story will continue, so stay tuned…

However it started, our Earth is incredibly, fully alive.

However it started, our Earth is incredibly, fully alive.

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