It’s not often we get to write about good news for science. Most of science is either starved for funding or under attack when not convenient for ultra-nationalist wingnuttery, or being hideously deformed to support some hare-brained point of conservative idiocy. But in one exciting field, there is some possible good news—provided the usual orcs don’t swoop in and kill it, as they are wont to do:
Today, the President signed the Consolidated Appropriations Act of 2017, which funds the U.S. government for the remainder of the fiscal year. NASA received $19.65 billion—its best budget since 2010—and the Planetary Science Division saw its budget increase to $1.846 billion—its best budget in more than ten years.
Needless to say, we are very pleased with this. It represents an increase of $215 million to planetary science above 2016, and is $345 million more than the President originally proposed for this year. When adjusting for inflation and programmatic consistency, this is the best budget for NASA's Planetary Science Division since 2005.
One of the most ambitious missions that got a boost toward reality under this budget is Europa Clipper. If this spacecraft is ever built and launched, it will explore the Galilean moons of Jupiter with emphasis on the most intriguing one of all: Europa. To enjoy a break from depressing news, and appreciate just how alien and yet how promising this strange little moon really is, you’ll need to follow me below.
At the dawn of the space age, as our moon slowly gave up its lifeless surface conditions, astronomers assumed the moons of gas giants like Saturn and Jupiter would be similar: dull, rocky wastelands, mostly frozen, and intermittently baked. So when unmanned probes finally gave us our first good glimpses of Jupiter’s inner satellites, it was quite a surprise. They showed active, dynamic worldlets, as different from one another in some ways as Mars is from Earth or Venus.
In particular, Io stole the show. It turned out to be the most volcanically active body in the entire solar system. Io is heated internally to the point of boiling by periodic interaction with Jupiter and its other large moons. There are so many massive volcanoes and vents and fresh lava plains on Io at any one time that new maps would have to be issued every few years to keep up with the ever-shifting landscape. It is quite literally hellish, a page out of Dante’s Inferno, right down to the sulfur compounds and pools of roiling lava. The active surface makes Io unique among the Jovian moons in that almost all the volatile ices that might have once existed there, and that do exist in quantity on the other three large moons, have probably long since been vaporized and boiled off into space.
Europa is the next moon out, and the tidal forces heating it are a little bit less intense. Europa is encased in ice. It’s mostly water ice as best we can tell, frozen hard as steel and dozens of miles thick. But underneath there is almost certainly a thick layer of liquid water that could be up to 100 miles deep. Underneath all that is probably a subdued version of fiery Io: an ocean bottom of ridges and volcanoes and thermal vents, perhaps features as familiar as black smokers or warm seeps, or maybe there’s totally alien manifestations of heat and pressure.
Planetary scientists are confident there is a large global ocean under several dozen kilometers of ice on this moon. How warm or cold it may be is a matter of debate. But it seems like there would be some calderas or hydrothermal vents. Which brings up the possibility of extremophile microbes clustered around them, like we see on the bottom of our own oceans.
That’s pure sci-fi speculation. We have no evidence there are vents at all, much less any alien communities supported by them. But it’s fun to imagine because this would be a biome both familiar and strange, and on a world that may be unique in our solar system but more common than Earth-like planets in our galaxy.
We know large gas giants revolving around stars are a common occurrence. We know gas giants tend to have lots of moons where tidal dynamics might be similar to what we see around Jupiter. There are even mini solar systems, such as the recently detected Trappist-1 system, where similar forces might be in play between tightly packed planets, heating the cores and liquifying the icy mantles of otherwise frozen wastelands. Those would be weird places to live.
In a hypothetical frozen world bursting with life on the warm, remote ocean bottom hidden under kilometers of water, the ground would the source of all heat and energy flowing into the strange ecology. The distant layers of thick ice would be like a solid sky shield far overhead, perhaps dotted with their own communities of microbes and other creatures. That shield would be critical in the case of a moon like Europa. It would protect the fragile warm seas from fierce radiation whipping around Jupiter so violently it would roast a human and cook unprotected microelectronics, much like a microwave oven on high. If any of those alien species ever arose to sentience and developed telescopic senses to become aware of planets like ours, they might feel pity for us poor creatures. We’re forced to eke out our lives, stranded and helpless, on the naked surface of a planet baking in the full nuclear glare beaming down on us from an unfiltered, uncaring sun.