The biggest planet in our solar system, Jupiter, has an incredible 67 known moons, with its 4th biggest satellite, Europa, containing all the key elements necessary for the origins of life, namely water, energy, and organic chemicals.
Needless to say, Europa has longed intrigued astronomers, and while scientists have yet to discover any aliens lurking on its surface, a recent discovery promises to make the search for life beneath Europa’s icy shell easier after what is believed to be plumes of salt water were recorded escaping through cracks in its surface.
The Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Telescope captured far-ultraviolet (FUV) images of the phenomenon, and while the photos are open to interpretation, a general consensus exists among astronomers that there’s a good possibility that the images do in fact show geysers.
Based on the images, it seems plausible that cracks in the ice and pressure are forcing the saltwater ocean located beneath Europa’s icy outer covering upward as geysers, similar to Old Faithful here on Earth. However, scientists believe that any geysers on Europa would not spout continuously like the one in Yellowstone National Park, but instead would lightly burst to life intermittently based on weather conditions.
Part of why so many scientists feel confident that the images taken by the STIS do in fact represent geysers is that evidence of the geological phenomenon has been spotted on Europa in the past. In 2012, for instance, the Hubble telescope caught sight of plumes of hydrogen and oxygen rising out of the same area on Europa, while in 2014 Hubble looking for features that absorb the reflected sunlight from Jupiter took a number of far ultraviolet images that might show geysers. As William Sparks of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, explains:
“Anything that absorbs [light] will appear in our image. We presume it to be water vapor or ice particles because that’s what Europa’s made of and those molecules do absorb at the wavelengths we observed at, which is why we chose those wavelengths.”
The STIS images are renewing interest in continuing the search for signs of life on Europa, and a flyby space mission has already been scheduled to launch in the 2020s, with the aim of taking more images and possibly flying through and capturing samples of any plumes that might be present on the moon. If such samples turn out to be water similar to what we have here on Earth, we may still not have enough information to know that life exists on Europa, however scientist might be able to detect organic chemistry that could indicate the potential for life. Elaborating further, William Sparks explained:
“Even if there is a small amount of biomass in the plumes as they start out from the ocean, by the time they get into space and the radiation environment of Europa at cryogenic temperatures, it’s not going to survive. We’d have to be looking for the remains of something that was once protected in the ice or under the ice.”
An expedition to Europa isn’t the only way to make astronomers more confident about the presence of geysers on the moon’s surface. If another telescope could duplicate the images and capture similar phenomenon in the same location, there would be less debate over whether or not what we’re seeing is actually a geyser, or perhaps some sort of irregularity or unexpected effect with the STIS.