Discovery, by nature, has a ripple effect. When one thing is found to be plausible, testable, or true, a suite of potential other truths and plausibilities tend to follow suit. This is the nature of inductive reasoning, the foundation of the scientific method, and the reason why science–as a human project–is generational. We discover something unexpected, and we celebrate twofold, threefold, and morefold, because its nuances and implications can ebb outwards, often lending hope to scientists working in entirely different fields.

Take the recent discovery of life in Lake Vostok, for instance: not a lake in the normal sense, Vostok is an underground Antarctic water reservoir, isolated from the outside world for 15 million years, a time-capsule long untapped. It has long been a question mark for science, a sort of myth. Dare we unseal this vault? In doing so, would we contaminate one of the last untouched places on Earth? Lake Vostok is, in essence, a frozen crypt, blocked from the sun by 4,000 meters of ice, laden with pressure, the coldest place in the world.

And yet, as we seem to discover with all our planet's most forbidding places, it harbors life. Over 3,500 DNA sequences, in fact, suggesting a complex ecosystem of relatively ordinary organisms, the type we might find in the bodies of fish and crustaceans, or in lakes and oceans around the world. "The bounds on what is habitable and what is not are changing," wrote the lead scientist on the genetic study of the Vostok water sample.

The ripple effect is this. Lake Vostok is a mighty fine analog for another seemingly inhospitable place for life: Jupiter's sixth moon, Europa. So this discovery of life beneath the ice is being welcomed not just by planetary biologists, but astrobiologists too. It might seem like a stretch to compare a frozen lake on Earth to a hunk of rock 390,400,000 miles away, but it's not rare for scientists to draw from Earth findings in making assumptions about space. Astrobiologists often study Earth's extremophiles–organisms which thrive in extreme conditions like hydrothermal vents, acid lakes, and deserts–snooping out their environments and evolutionary pathways, in order to understand how such life might evolve elsewhere in the universe. Finding microbes that can survive the glacial embrace of Lake Vostok, hidden away from the sun, provides clues about other, similar environments. Like, improbably, an alien moon.

Beyond any scientific purpose, Vostok to Europa is a tantalizing parallel to make. For one, comparing a place on Earth to an outer-space ocean serves to remind us how strange and wonderful our planet really is. It recontexualizes us. All of the aliens on Earth, from deep sea creatures to strange microbes, and maybe the conscious bipeds too, look different through this lens. As for the ocean on a faraway moon, both recognizable and horribly, horribly strange–it's just the kind of uncanny setting we love to create myths and fantasies about. To wit: the science-fiction film Europa Report, very recently released on demand, runs with the notion of subglacial life, launching its international cast across the solar system and onto Europa's harsh, sulfurous surface, where they discover, at great cost, the slumbering mysteries looming beneath. Hint: they're not microbes, unless those microbes were dreamt up by H.P. Lovecraft.

Europa's mystique might also have a little to do with its star turn in the kinda-underrated sequel to 2001: A Space Odyssey, 2010: The Year We Make Contact, in which a cryptic final message is transmitted to Earth:

ALL THESE WORLDS

ARE YOURS EXCEPT

EUROPA

ATTEMPT NO

LANDING THERE

USE THEM TOGETHER

USE THEM IN PEACE

However, the recent media coverage (and science fiction) regarding Europa/Vostok ignores something important: of these two desolate places, we are asking two very different questions. We know that Lake Vostok, some 35 million years ago, may have been open to the air, surrounded by a forest, and relatively warm. In boring through its icy ceiling, no one was trying to discover whether life could have arisen there, only if it could have survived the changes since its temperate origins. On Europa, that's not a distinction we have the luxury to make–under its hulking ice, survival and existence would be compounded into a single discovery.

And what a discovery it would be! My friend, the writer & scientist Fred C. Adams, once speculated to me about creatures trapped beneath Europa's ice, completely ignorant of the vast cosmos above and around them, blind to the stars. Imagine breaking through to such a hidden world. It would be a first contact of the purest order. It reminds me, too, of Carl Sagan's loopy imaginations, in the opening chapters of Cosmos, of lifeforms that could exist on a gas giant like Jupiter. Billowing like jellyfish, the size of cities, they'd ride the buoyant gases of the Jovian atmosphere, eating the sun. "Physics and chemistry permit such lifeforms," Sagan wrote. "Art endows them with a certain charm. Nature, however, is not obliged to follow our speculations."