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Gibbous Europa (Credit: Galileo Project, JPL, NASA)

Gibbous Europa
(Credit: Galileo Project, JPL, NASA)

Tonight is Yuri’s Night, when space enthusiasts around the world celebrate the first human trip to outer space made by Yuri Gagarin fifty two years ago.  You can read about Yuri here.   It is an excellent occasion to assess what is most exciting in space exploration.  Unfortunately nobody has jumped forward to build a floating colony on Venus.  Indeed NASA seems rather flat footed lately—building a series of colorless rockets and sending successive similar rovers to Mars.  Fortunately there is one exciting mission which still has not definitively been cancelled because of budget stalemate.

Proposed Europa Clipper (NASA)

Proposed Europa Clipper (NASA)

The Europa Clipper mission is a $2bn dollar project to launch a probe to Jupiter’s moon Europa, a large icy satellite covered in cracked ice.  Europa is slightly smaller than Earth’s moon and has a thin oxygen atmosphere.  It is one of the smoothest items in the solar system.   Astronomers believe that an ocean of liquid water lies beneath Europa which is warmed by tidal flexing (a process which causes orbital and rotational energy to be converted into heat).   The surface of Europa is bathed in exotic radiation which rips apart water molecules and leaves oxidants like hydrogen peroxide.  All of this means that Europa is the most likely planet in the solar system to harbor unknown life.  It has even been theorized that beneath the ice the ocean could have black smoker type environments–and just possibly thermal vent or “cold seep” ecosystems.

Artist's concept of the cryobot and hydrobot probes (NASA)

Artist’s concept of the cryobot and hydrobot probes (NASA)

Because of this, scientists have been anxious to get a closer look at the intriguing moon.  Various proposals have been put forward for missions directly to the moon. The Pioneer and Voyager spacecraft took pictures of it as they flew through the solar system and subsequent missions also took readings and photos—but there has been no Europa-centric mission to really find out about the oceans below the cracked ice.  One (amazing!) proposal was to send a nuclear powered melt probe to melt through the ice and sink to the bottom of the ocean, whereupon a mini-sub probe would emerge and explore the extraterrestrial ocean!  That plan was shelved because it was too expensive (and nobody could figure out how to sterilize the probe).  The proposed Europa Clipper mission is more modest but still quite amazing. Here’s how the Jet Propulsion Laboratory describes it:

The Europa Clipper mission would send a highly capable, radiation-tolerant spacecraft into a long, looping orbit around Jupiter to perform repeated close flybys of Europa.

The possible payload of science instruments under consideration includes radar to penetrate the frozen crust and determine the thickness of the ice shell, an infrared spectrometer to investigate the composition of Europa’s surface materials, a topographic camera for high-resolution imaging of surface features, and an ion and neutral mass spectrometer to analyze the moon’s trace atmosphere during flybys…The nominal Europa Clipper mission would perform 32 flybys of Europa at altitudes varying from 2700 km to 25 km.

That sounds amazing!  Join me in lifting a glass to Yuri Gagarin and also join me in hoping that our moribund government funds this far-sighted mission to what might be life’s other home in the solar system!

Yuri Gagarin--the first human to go to space

Yuri Gagarin–the first human to go to space

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.

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