Jupiter’s moon Europa has an icy shell that conceals a liquid water ocean. Now, scientists have made the primary direct measurement of water vapor in Europa’s environment. It’s the most effective proof but for a water plume erupting from the moon’s floor.
The measurements additionally suggest that exterior of plume occasions, Europa’s environment possible has much less water vapor general than beforehand thought. The scientists describe their findings Monday in Nature Astronomy.
A Watery Moon
Scientists have identified because the 1960s that Europa is dwelling to water ice and, possible, a liquid water ocean beneath the floor. They predicted that radiation from Jupiter would bombard the moon’s icy floor and create water vapor.
And recent studies have turned up oblique proof that erupting plumes inject water vapor into the moon’s environment. Studies prior to now decade have even noticed indicators of hydrogen and oxygen in Europa’s environment, however not water vapor straight.
In the brand new examine, researchers used a telescope on the Keck Observatory in Hawaii to go looking Europa for particular infrared wavelengths of sunshine that water vapor would emit. They noticed the moon on 17 completely different dates from February 2016 to May 2017. Their devices didn’t decide up indicators of water vapor on 16 of these nights. But on April 26, 2016, they measured a big quantity — roughly 2,000 metric tons — of water vapor.
Looking for Vapor
Though the researchers didn’t see indicators of water vapor on the opposite 16 nights, that doesn’t imply there wasn’t any. In reality, the researchers consider some water vapor exists in Europa’s environment always due to Jupiter’s radiation impact, as earlier research have proven. There was in all probability simply too little water vapor for his or her devices to have the ability to detect.
However, general, the measurements suggest that the standard quantity of water vapor in Europa’s environment might be lower than beforehand thought. This additionally implies that the standout April 2016 measurement possible got here from a one-time occasion, like a water plume.
Upcoming house missions, like Europa Clipper and JUICE (JUpiter ICy moons Explorer), will get a more in-depth take a look at the moon.
“I’m really looking forward to follow-up studies of Europa and other ocean worlds,” mentioned Lucas Paganini, a NASA planetary scientist and one of many new paper’s authors. “It has been difficult to detect water in liquid form. These detections of water in vapor form, I think, is the closest thing we have in the search for liquid water environments.”