Searching for life on Europa just got a lot easier
Of all the planets and moons in the solar system, few are as attractive to astronomers and scientists as Jupiter’s moon, Europa. The Jovian moon has a rocky core and is covered in liquid, which is hidden beneath a deep layer of ice. The combination of liquid and the warmth generated from orbiting the gas giant has made it a possible host to life of some sort.
The real question is how do we check?
Europa is high on the list of celestial bodies that NASA wants to thoroughly explore, second only to Mars. Reaching the moon is much, much more difficult than reaching the Red Planet, however, and even if we do, that’s just the start of it. Ideally, NASA would need to land on the ice, drill or break through the ice, collect samples, and then send those samples back. It’s a huge undertaking, but it may have just got significantly easier.
NASA recently announced that it has discovered what appear to be ice plumes on the surface of Europa. These plumes project water high into the atmosphere through cryovolcanoes, which means a probe would – theoretically – be able to collect a sample without landing or drilling.
“Europa’s ocean is considered to be one of the most promising places that could potentially harbor life in the solar system,” said Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “These plumes, if they do indeed exist, may provide another way to sample Europa’s subsurface.”
Although the temperature on Europa is around -260F (-160C), the icy shell covers oceans containing twice as much liquid as found on0 Earth. The plumes are estimated to shoot materials about 125 miles before they all come back down to the surface, which could allow us to test the water without having to deal with the ice. The first signs of plumes came years ago, but new research led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore observed what appear to be plumes as the moon passed in front of Jupiter.
The next step will be to use the infrared vision of NASA’s James Webb Space Telescope, which is scheduled to launch in 2018. Those plumes could also help us to understand the chemical composition of the liquid, even at a distance. NASA is currently planning a mission to Europa in the 2020s, while the European Space Agency is planning a mission to a few Jovian moons, including Europa. Neither are specifically designed to search for life, but they could help to prepare future missions.
If a craft could collect material from a plume, it could then analyze the sample onboard and send back the results. There is precedent for this – on October 28, 2015, the Cassini spacecraft flew through a plume on Saturn’s moon Enceladus, coming within 30 miles of the surface to collect ice and dust. It collected material and sent the findings back to Earth.
To obtain the samples without utilizing the plumes, a craft would need to land on the ice, which in itself is a tricky proposal – even if the landing area is smooth, the thickness of the ice is unknown. It may be thick enough to support the landing of a craft (and the heat from the engines as it landed), but that may make it too deep to reach the liquid. There’s also the question of how to make it through the ice.
The ice is expected to be at least a kilometer thick. On Earth, that would be easy to drill through; on a distant moon, without human interaction, it would incredibly difficult. The easier solution would be to drop a radioactive ball that can melt through the ice. That would easily cut through the frozen liquid, but it would also introduce radioactive material to an alien world. Even if the material were miniscule and had a short half-life, it is still ethically and ecologically questionable.
To add to the complications, a probe that landed would likely need to consist of two separate modules. The first would land on the planet and collect the sample, while the second would remain in orbit and act as a signal booster to send the collected data back to Earth. This has been done before, but it makes any potential spacecraft more complex and expensive than a single craft that could reach the plumes.
One day, sooner or later, we will make it to Europa, possibly with the EM Drive. And when we do, our understanding of life in the solar system may radically change.