Astronomers have discovered what they think are massive water vapour plumes erupting on Jupiter's moon, Europa, boosting the chance of finding life there.
According to NASA, which made the announcement on Monday, the finding "bolsters other Hubble observations suggesting the icy moon erupts with high altitude water vapour plumes."
The finding also means missions to Europa could sample the moon's hidden ocean without having to drill through miles of ice.
Europa contains an ocean with twice as much water in it as the Earth's oceans, but it is protected by a layer of ice of unknown thickness.
"Europa's ocean is considered to be one of the most promising places that could potentially harbour 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."
NASA said the plumes are estimated to rise about 200 kilometres before, presumably, raining material back down onto the moon's surface. The plumes provide a tantalising opportunity to gather samples originating from under the surface without having to land or drill through the ice.
Scientists hope the spacecraft could study the water vapour plumes' chemical makeup to reveal characteristics of the water without having to drill through the ice.
Jupiter, nicknamed the king of the solar system, is surrounded by more than 50 moons.
Last year, data from the Hubble Space Telescope confirmed that Jupiter's largest moon, Ganymede, has an underground ocean that contains more water than Earth's, broadening the hunt for places in the solar system where life might be able to exist.
n the case of Ganymede, aurorae - displays of light in the atmosphere - glimpsed by the Hubble Space Telescope allowed scientists to confirm the long-suspected subsurface saltwater there.
Because aurorae are controlled by a moon or planet's magnetic field, observing changes in their behaviour can lead to better understanding of what exists under the surface.
The team that found the plumes on Europa was led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore.
The team observed these finger-like projections while viewing Europa's limb as the moon passed in front of Jupiter.
In 10 separate occurrences spanning 15 months, the team observed Europa passing in front of Jupiter. They saw what could be plumes erupting on three of these occasions.
The solar system's largest planet, Jupiter is the fifth from the Sun. NASA's $US1.1 billion (NZ$1.5 billion) Juno spacecraft successfully slipped into orbit around the planet in July on a 20-month mission to learn more about how the gas giant formed, and to probe the origins of the solar system.