Convection May Explain Europa's Weird Chaotic Terrain
Europa, one of Jupiter’s largest moons, is often cited as the most likely place in the solar system (other than Earth) to harbor life as we know it. It has all the components to support a significant biomass leading some scientists to go “all in,” suggesting that complex lifeforms may be supported in the vast liquid oceans of water under its thick icy crust. While we ponder what lies beneath, there are a few mysteries on Europa’s surface that still perplex planetary scientists.
The fact that Europa has large swathes of ice covering its globe is clear as there is an obvious lack of impact craters. If Jupiter’s other rocky satellites are anything to go by, Europa should be riddled with pockmarks. But it’s not. Undoubtedly, Europa has been hit countless times by errant asteroids, but its constantly churning liquid interior recycles the surface ice, removing any trace of craters quickly.
The smooth regions of ice are therefore expected — but what about the craggy, chaotic regions that compose 40 percent of Europa’s surface? Until now, with few direct measurements to work with, scientists have been at a loss to explain them.
In new research published in the journal Nature Geoscience (doi:10.1038/ngeo2021), researchers from the University of Texas and the Max Planck Institute in Germany used archive data from NASA’s Voyager 1 flyby in 1979 and NASA’s Galileo mission (that orbited Jupiter from 1995 to 2003) to produce theoretical model of convection currents in Europa’s ocean to see how they may influence surface features.
As pointed out by the researchers, the vast majority of chaos regions can be found within 40 degrees of the equator and that observed salt deposits on Europa’s surface suggests a geologically active crust that interacts with the liquid interior.
The root cause of the chaos regions, argue the researchers, is down to the flow of internal heat toward the equator, impacting the structure of the ice above. Convection currents inside the moon’s subsurface ocean heats the equatorial ice, melting it. The ice then refreezes and the cycle begins all over again, creating a jagged, chaotic terrain.
Other theories have been suggested for the creation of these chaotic regions, such as solar heating and tidal interactions with Jupiter, but interior convection currents appear to better model the observed landscape features.
Unfortunately, computer simulations can only go so far in explaining the mechanisms behind planetary science; we can only fully investigate Europa’s mysterious allure by sending orbiters and, preferably, robotic landers to get up close and personal with Europan ice.
Sadly, as NASA’s budget woes roll toward 2014, there are increasingly ominous signs that the space agency’s planetary sciences budget will suffer another, potentially devastating blow in the coming months. During a NASA planetary science meeting on Tuesday, the extent of the damage of the U.S. government sequester became gut-wrenchingly clear.
In a Twitter update, Caltech planetary scientist Mike Brown said: “Wow. NASA is currently have a Town Hall meeting and essentially telling planetary scientists to look for new jobs. Wow.”
NASA is home to the world’s premier planetary research projects, including NASA’s Cassini mission to Saturn, the rover missions to Mars and all other robotic missions beyond Earth. Should this jewel in America’s scientific crown be cut any further, any hope of sending missions to Europa (or any other promising planetary bodies for that matter) will vaporize, potentially crippling planetary exploration for decades to come.
Image: Left: The computer simulation showing a 3D cut-away of the Europa convection flow simulation. Right: Voyager 1 observation of Europa’s icy crust. Credits: K. M. Soderlund (left), NASA (right)