Astronomers at the National Aeronautics and Space Administration (NASA) have discovered more evidence of water or other liquids erupting from beneath the surface of Europa, one of the many moons of Jupiter.
They have new evidence of water plumes on Europa's surface and are now more confident that water samples can be collected and studied by future NASA missions without drilling through layers of ice.
Observations made by several NASA missions over the last couple of decades have hinted at the presence of a subsurface ocean on Europa, one of Jupiter's largest moons.
The Hubble telescope has now collected images that show the absorption of ultraviolet wavelengths by what researchers believe are water plumes emanating from Europa's south pole.
A team from the Space Telescope Science Institute (STScI) made the observations using the Hubble Space Telescope, and the agency announced the findings during a teleconference on Monday afternoon. The full findings will be published in the Astrophysical Journal on 29 September.
The STScI team watched Europa travel across the face of Jupiter on 10 different occasions over a period of 15 months, starting in December of 2013. During three of those transits, the team captured what appeared to be plumes of water vapour erupting from near the icy moon's south pole.
"If there are plumes emerging from Europa, it is significant because it means we may be able to explore that ocean for organic chemicals or even signs of life without having to drill through unknown miles of ice," the New Scientist quoted William Sparks, an astronomer at the Space Telescope Science Institute in Baltimore as saying.
Sparks' team used Hubble to measure Europa's atmosphere as the moon transited across the bright background of Jupiter, a technique similar to what planetary scientists use to determine the atmospheric qualities of exoplanets.
The light coming from the bigger, brighter object in the background makes it easier to see features at the edges of smaller, more dimly lit objects in the foreground.
What Sparks' team saw was one step closer to direct images of water plumes. Dark splotches appeared in the same southern region of Europa every few months, hinting that Europa's surface breaks up now and then due to the massive gravity of Jupiter. When the surface cracks, the rifts sometimes run deep enough to release water into the atmosphere from the ocean below.
The team estimates that these plumes shoot out about 125 miles (200 kilometers) above Europa before they fall back down to the surface, similar to estimates from the 2012 observations.
NASA has found evidence of water all over our solar system, but the agency has only directly spotted geysers on one body - Enceladus, a moon of Saturn.
Scientists have long believed that Europa is home to a subsurface ocean, but it took until 2012 to find evidence of water plumes erupting from that ocean.