As someone, possibly Jake from Animorphs, once observed, Earth is a tough neighborhood. A feature at Smithsonian magazine illustrates this memorably, noting the regions and circumstances where it doesn't make sense for life to exist, yet where it somehow turns up.

There are a few great counterintuitive examples, like the pupfish colonies soldiering on in Death Valley's aquifers and springs, or the Desulforudis audaxviator bacteria that lives in complete biological isolation at the bottom of a gold mine in South Africa. (D. audaxviator is named after a passage in — what else? — Jules Verne's Journey to the Center of the Earth, from the Latin for "bold traveler.")

Other places where life springs eternal: on the surface of pools of acidic mining runoff; drifting in the stratosphere at altitudes of more than eleven miles; and in facilities at the Carnegie Institution, where scientists accidentally exposed strains of E. coli to pressures of 16,000 atmospheres, theoretically more than life can withstand, only to find that a number of the samples had survived.

Then there are the Jurassic bacteria, preserved in spore form in Antarctic ice for millions of years and resuscitated in modern labs — not unlike Philip J. Fry, except less likely to leave a hat full of milk in a storage locker.

If nothing else, this extremophiles' hall of fame lends some hope to those awaiting reports of extraplanetary biota. There's water on the moon, possible Martian microbe fossils in a crashed meteorite, and the potential for oceans of Jovian fish on oxygen-lousy Europa. If a previously unknown phylum of bacteria can be discovered in Yellowstone's near-boiling hot springs, why couldn't there be something waiting out there in the star-system suburbs?

Top ten places where life shouldn't exist… but does [Smithsonian]

Apparently, the oceans of Europa are fed with more than 100 times more oxygen than previous models suggested. According to National Geographic:

That amount of oxygen would be enough to support more than just microscopic life-forms: At least three million tons of fishlike creatures could theoretically live and breathe on Europa, said study author Richard Greenberg of the University of Arizona in Tucson.

"There's nothing saying there is life there now," said Greenberg, who presented his work last month at a meeting of the American Astronomical Society's Division for Planetary Sciences. "But we do know there are the physical conditions to support it."

In fact, based on what we know about the Jovian moon, parts of Europa's seafloor should greatly resemble the environments around Earth's deep-ocean hydrothermal vents, said deep-sea molecular ecologist Timothy Shank.

"I'd be shocked if no life existed on Europa," said Shank, of the Woods Hole Oceanographic Institution.

So how does the oxygen get into the water? It's created when charged particles from Jupiter's magnetic field hit the ice. Because the icy surface of the moon is constantly shifting and cracking due to tides created by both the Sun and Jupiter's gravitational fields, the oxygenated ice would crumble down into the oceans. Eventually, this would result in oxygen-rich waters like those in our own oceans. And these could possibly support Earth-ish life.

As of yet, no space probes from Earth have penetrated Europa's ice crust to examine the seas below, but NASA has proposed another mission to place a satellite in orbit around the moon. (No, they would not be crashing the satellite into the moon itself.)

via National Geographic

Richard Greenberg of the University of Arizona will be presenting his findings on Europa today at American Astronomical Society's Division for Planetary Sciences. Europa's ability to support macrofauna — more complex organisms like animals — hinges on how much oxygen is contained in the suspected ocean beneath the moon's icy surface.

Greenberg believes that energetic particles from the sun are able to reach Europa's subterranean ocean despite that layer of ice. Because the surface of Europa is relatively impact-free, the ice is believed to be relatively new, about 50 million years. Based on this, Greenberg sets forth the idea that Europa is being constantly resurfaced, possibly with fresh materials, thanks to oxidizers at the planet's surface. He also estimates that, if there were, say, fish on Europa, and those fish used the same amount of oxygen as Earth fish, the moon's ocean has enough oxygen to support 6.6 billion pounds of such macrofauna.

Of course, just because Europa might be able to sustain life doesn't mean we'll find life there. But this does present the possibility that other bodies produce enough oxygen to support complex biological processes.

Europa, Jupiter's Moon, Could Support Complex Life [Discovery]

The scientists found the bacteria, named Herminiimonas glaciei, buried under nearly 2 miles worth of ice in Greenland. Scientists think that, since it's small even for bacteria, it survives on nutrients trapped in veins of ice and uses its flagella to move within veins to seek food.

It took the scientists almost a year to revive the bacteria and coax it to grow; once it did, it yielded small colonies of purple-brown bacteria. Although not as old as the 8 million year old bacteria resurrected from Antarctic ice in 2007, it does lead the Penn State scientists to believe that they might be able to find and re-grow bacteria from Mars or Jupiter's moon Europa:

All we can say is that because ice is the best medium to preserve nucleic acids, other organic compounds and cells, the potential for finding them in these environments is quite high because of the cold... It gives us hope that if something is there, we can locate it.

Because that turned out well for scientists in Species.

'Resurrection bug' revived after 120,000 years [New Scientist]
Eight-million-year-old bug is alive and growing [New Scientist]

Previous experiments have shown that microbes can survive in the punishing cold of space. Their ability to hide out in a rock's interior, safe from a vacuum is well-documented too.

But scientists haven't been able to tell whether hearty critters could survive the heat and crushing force of an asteroid impact that would be needed to eject them into space in the first place. Astrobiologists at the Institute of Aerospace Medicine in Germany have finally connected all the dots with a new experiment in the Spring issue of Astrobiology Magazine

And what better way to simulate an asteroid impact than to smash rocks together? That's exactly what the scientists involved in this research did, after sprinkling test rocks with bacteria known live inside stone, some cyanobacteria, and a dash of lichen onto them. All three lifeforms survived the high-speed collision, suggesting they could be floating through outer space even now, waiting for a chance encounter with distant planet to plant the seeds of a whole new 'alien' biosphere.

Source: Astrobiology Magazine

Image: NASA

Crowning a moon champion ain't as easy as it seems when Saturn alone has 59 of them. Fortunately the field got smaller when we considered five key points all moons should have on their resumes. It may be hard to stomach having Charon up there — it's questionable that it's even a moon — but someone had to be the goat.

And now, the winners in the individual categories:

BEST FEATURE NAME: Despite tons of creative feature names, Europa wins by a wide margin with Rathmore Chaos. It sounds like a level of Hell from Dante's Inferno, but like most of the outer system, the Chaos is a cold place. In fact it's a jumble of broken up ice that's evidence of the moon's active ice tectonics...and maybe a liquid water ocean below.

POTENTIAL FOR COLONIZATION: Phobos gave Earth's Luna a run for it's money; it's low gravity and proximity to the Red Planet make it worthy of it's full score. But in the end the deck's stacked against the Martian moon — the stated goal for NASA's next generation of manned spaceflight is to return to the moon...to stay.

ACTIVE GEOLOGY: This is a toughy. Uranus' moon Miranda doesn't have active geology, but scientists speculate that the whole moon may have been obliterated by impacts, then reassembled itself. You know, like T-1000 in Terminator 2. Charon, Triton, and Enceladus all look like they've got actively erupting cryovolcanoes of frigid ammonia, water, or liquid nitrogen which is cool, but it knocks Titan down a notch in uniqueness. Jupiter's Io wins for it's self sacrifice though; riddled with volcanoes, the firey moon is literally gutting itself, spewing 1 ton of sulfur dioxide into space every second.

MOVIE/BOOK: The hands-down winner is Earth's Moon, which has been in books and movies since the art forms were invented. It's hardly a fair fight, so the prize goes to Jupiter's Ganymede. The largest moon in the solar system (that's right, bigger than Titan!), it haunts tons of Philip K. Dick's books.

POTENTIAL FOR LIFE: Cryovolcanoes are going off all over the solar system's icy moons, and where there are volcanoes, there's liquid. Most of the liquid is in the form of methane, ammonia, nitrogen, or some other substance that Earth-life wouldn't want to swim in, but who knows what sort of strange aliens could be out there?

That said, Europa's icy shell is made of old-fashioned H2O, and features like Rathmore Chaos look a lot like shifting pack ice here on Earth, which floats on a big ocean of salty water, which in turn contains tons of critters. There's a good chance the same is true on Europa, meaning....

the prize for THE OVERALL AWESOMEST MOON IN THE SOLAR SYSTEM goes to EUROPA!!! Honorable mention to TItan for a strong showing, but it just goes to show...don't mess with the moon with the water oceans under the ice!

Sources: Lunar and Planetary Institute

The Cascadia Astrobiology Institute

Science Direct

WIkipedia

The Nine Planets Solar System Tour

I love this picture because I'm just finishing up John Varley's new novel Rolling Thunder (due out in March), which is partly set on Europa. The main character has a view of Jupiter from her window in the habitat where she lives on Europa. Image via NASA.

And finally, here's a nice image for getting some perspective on where the Kuiper Belt and Oort Cloud are relative to the rest of the solar system. Image via NASA.

Top image via Calvin J. Hamilton.