Scientists believe an ocean lurks beneath Europa’s icy shell. Evidence of this ocean first surfaced in the late 1970s when the Voyager spacecraft flew by the moon. The images weren’t the best, but they revealed a cracked, icy surface with few craters. Anyone who follows astronomy knows that means the current surface must be young. The refreshing of ice on Europa’s surface supports the theory of an ocean lying beneath.
In 1997, the Galileo probe soared past Europa. Its instruments noticed a magnetic field that is probably caused by saltwater circulating in a global ocean. And recently, scientists found evidence the moon’s ocean is mixing with the surface.
Bottom line? We are almost certain Europa’s icy surface hides a massive ocean. And where there is water, there is the potential for life. That’s why NASA is gearing up to send a spacecraft to study the intriguing world. But we are still several years away from launching it. Right now, NASA doesn’t plan to launch the spacecraft until the 2020s. Add a few more years on top of that to get to Jupiter.
Artist concept of Europa’s ocean.
What scientists found this week
A new NASA study modeled the chemical conditions inside Europa’s ocean. Having water isn’t enough for life to exist. You need “the necessary balance of chemical energy for life,” says NASA.
“We’re studying an alien ocean using methods developed to understand the movement of energy and nutrients in Earth’s own systems,” said Steve Vance, a planetary scientist at JPL and the lead author of the study. “The cycling of oxygen and hydrogen in Europa’s ocean will be a major driver for Europa’s ocean chemistry and any life there, just as it is on Earth.”
To shed light on this chemical balance, Vance and his colleagues tried to figure out how much hydrogen could be produced in a process called serpentinization. This is when seawater seeps through and reacts with rocks to form new minerals, releasing hydrogen as it does so.
The researchers also looked at oxidants (oxygen and other compounds that could potentially react with the hydrogen. Because scientists believe Europa’s ocean mixes with the surface, oxidants from the ice would enter the ocean.
“The oxidants from the ice are like the positive terminal of a battery, and the chemicals from the seafloor, called reductants, are like the negative terminal. Whether or not life and biological processes complete the circuit is part of what motivates our exploration of Europa,” said Kevin Hand, a co-author on the study.
The new study indicates Europa’s ocean may support life even without volcanism. Vance explains how the chemical balance would still be ok without volcanism. “If the rock is cold, it’s easier to fracture. This allows for a huge amount of hydrogen to be produced by serpentinization that would balance the oxidants in a ratio comparable to that in Earth’s oceans,” said Vance.
Did You Know: This spacecraft won’t orbit Europa. Because of the intense radiation from Jupiter, NASA plans to insert the spacecraft into an orbit of the large planet instead. This helps protect the spacecraft from the harmful radiation spewing from the gas giant. So, how will it study Europa? Every two weeks, the spacecraft will orbit Jupiter. And during these orbits, it will fly by the icy moon. The official mission plan calls for 45 flybys.
Is Europa the intriguing world we believe it to be? That’s what this mission will answer. One of Europa’s nine instruments, the Europa Thermal Emission Imaging System (E-THEMIS) will scour the surface looking for plumes of water erupting from the surface.
NASA missions always reveal plenty of surprises. Pluto continues to stun astronomy fans everywhere. Cross your fingers that Europa will be just as stunning.