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This week’s posts [concerning translucent sea slugs, wasps named for a crazy pop star, an elusive Indochinese cousin of the cow, and whole sunless ecoystems] have all been about finding new life-forms.  There is, of course, only one place such a topic can ultimately wind up—far beyond the living jungles, azure seas, and swirling clouds of our beautiful home planet, out in the immensity of space where the greatest question of all waits like a magic golden apple spinning in darkness.

Is there life elsewhere?

Unfortunately the current answer is incomplete: all known life–in all of its ineffable variety–is Earth-based…yet the universe is vast beyond comprehension.  So I’m going to mark this down as “probably.”

Chang E and the Lunarians

Many ancient societies reckoned that other worlds existed.  The Norse had their nine worlds joined together by the great ash tree Yggrdasil.  The Chinese had myths about Chang’e and the Jade rabbit on the moon. Even the stolid Christians believe in heaven & hell, which are places filled with intelligent beings that are not on earth (ergo, alien realms somewhere out there in the multiverse).  William Herschel, great astronomer of the Enlightenment, believed that life was everwhere—particularly everywhere in the solar system.

Sigh–those were simpler times…

When humankind entered space age, we used our burgeoning technology to examine the solar system for signs of Sir William’s spacefolk.  Although we did not find the Venusian space hotties we were looking for (dammit), we did discover that among our neighboring planets, there are several other possible homes for earthlike living things.  The cloud tops of Venus are inviting and could host bacteria-like life (although I hope not, since I want us to build a second home there).  For centuries, scientists and fabulists speculated about life of Mars.  We now know that the Martian magnetosphere died and the planet’s atmosphere was swept away, but perhaps there are some hardy extremophile bacteria living in the Martian rocks somewhere.  It’s a sad scenario to imagine them on their dying world—like little kids left in a bathtub going cold.  Certain moons of Jupiter & Saturn seem to be the real best bet for life in the solar system.  The Jovian moons Europa, Ganymede, and Callisto are all believed to have extensive liquid oceans beneath their crust.  Likewise the Saturn moons Titan and Enceladus are believed to have subsurface water. The discovery of life on Earth which did not directly require photosynthesis (like the cold seeps from yesterday’s post) has given scientists hope that bacterial mats—or maybe something even more advanced–exists on one of these moons.

So maybe there are some bacteria analogs or conodont-like creatures squiggling around in some cranny of the solar system.  Perhaps life takes on an unknown form and we already flew over a clever, good-hearted ammonia-based life form on Enceladus (which NASA analysts then promptly dismissed as a snowbank), but I doubt it.  The true answers to the questions about life lie out there among the stars.  Exoplanets are being discovered at a tremendous rate and everyone hopes that some of the more earthlike examples harbor life.  Unfortunately our technology is nowhere close to being able to spot the planets themselves and gauge whether life is there by means of spectrograph.  We are stuck waiting for peers who are either broadcasting radio signals or screwing around with the fundamental nature of existence in such a way that would bring them to our attention.  Indeed as humankind’s technological savvy grows, scientists are looking for more sophisticated signs of advanced life such as black holes of less than 3.5 solar masses or sophisticated particle radiation which could only be created (or detected) by civilizations of huge sophistication.  All we can say right now is that, after a hundred years of looking, we have not found a lot of radio chatter in our neck of the galaxy—which is an answer of sorts itself.

Perhaps we are among the first sentient beings in this area of space (or anywhere, for that matter).  The first generation of stars had to live and die before there were any raw materials for chemically based life. It took billions of years to get where we are, and, despite a few perilous missteps and accidents, life on Earth has been lucky.  In my opinion some of those planets we are discovering are almost certainly covered with microbial life, but not many have little green scientists in many-armed lab coats firing up their radio telescopes (or forging little suits of chain mail a few hundred years behind us).

The Arecibo message as sent 1974 from the Arecibo Observatory.

In writing about the Curiosity rover, I humorously mentioned how much it looked like the aliens from golden age science fiction. It seems we are also broadcasting retro style messages to the stars.  Above is the print-out version of the Arecibo message—one of the loudest broadcasts we have sent.  It’s like a macramé knitted by Dr. Zoidberg’s great aunt or a valentine from Atari’s space invaders! Imagine if you pointed your radio telescope at the heavens and received a message like that!  Maybe the aliens are scared of us or maybe they don’t want to talk to a species with such homespun tastes!

Some day in the future (artist’s interpretation)

So, after the whole post we are no closer to knowing if there is life in the cosmos, but what did you expect?  Did you think I would tell you some secret here before you saw it blaring out of every news station on the planet? [If you did think that, then thank you so much!]  I believe that extraterrestrial life is out there.  I even believe that intelligent extraterrestrials are out there, but the universe really is ridiculously, ridiculously vast.  It’s going to take a while to find our fellow living beings.  In the mean time have faith (which is not advice I thought I would be giving) and keep looking up at the cold distant heavens.

An artist's conception of the earthlike world, HD 85512 b (CREDIT: ESO/M. Kornmesser)

Today it was reported that HARPS, (High Accuracy Radial velocity Planet Searcher) a device operated from the European Southern Observatory’s station atop Mount la Silla in the Andes, has discovered 50 new exoplanets (planets which orbit stars other than the sun).  Sixteen of these new planets are “super-earths” rocky planets with a mass from 1 to 10 times that of our planet. One of these newly-discovered planets, HD 85512 b, is estimated to be only three-and-a-half times the mass of the Earth and it seems like it is located at the edge of the habitable zone, the orbital belt around a star where water can exist in liquid form.  This is only the second exoplanet discovered within the habitable zone, the first being Gliese 581 d.  Interestingly HARPS has disproved the existence of Gliese 581 g (which I wrote about last year) as a mathematical phantasm–so um, you might want to take that post with a grain of salt. The planet HD 85512 b orbits a star which is is approximately 35 light years from Earth.

In the eight years since the program has started, HARPS has discovered more than 150 exoplanets. HARPS discovers new planets by means of a mind-boggling technology: a spectrograph of stupendous precision is mounted on a 3.6 meter telescope in order to take painstaking observations of numerous nearby stars over a prolonged period of time.  A computer program then compares the tiny variances in the light emitted by these stars.  Stars with planets orbiting them undergo slight changes of radial velocity as the planets’ gravity tugs lightly at the stellar bodies. These shifts can be measured via Doppler shift and compared against the expected spectrographic signature caused by the stars relative drift toward or away from the observatory. Over many years the computer can thereby model the mass and approximate orbit of planets around stars (considering the math and the precise observations required for such calculations makes my hair stand on end).

Kepler, the NASA exoplanet discovery project uses an entirely different technology which involves measuring changes in brightness caused by the transit of a planet across a star’s glowing face.

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