27 May, 2018
A fresh look at old data is giving scientists a new reason to consider Europa, a moon orbiting the planet Jupiter, as a leading candidate in the search for life beyond Earth.
The reason: evidence of water from the moon shooting into space.
NASA, the American space agency, noted an unusual shape -- a bend -- in Europa's magnetic field in 1997. That was the year when NASA's Galileo spacecraft passed close to the moon. For a time, it was about 200 kilometers above the surface.
Scientists reported earlier this month on their reexamination of the Galileo data. They now think this bend in the magnetic field could be explained by an active geyser in an underground ocean. The scientists believe the spacecraft traveled through a plume of water.
Elizabeth Turtle is a planetary scientist with the Johns Hopkins University Applied Physics Laboratory. She told reporters that Europa does have a lot of the qualities that are necessary for life was we know it.
"There's water. There's energy. There's some amount of carbon material. But the habitability of Europa is one of the big questions that we want to understand," said Turtle.
"And one of the really exciting things about detection of a plume is that that means there may be ways that the material from the ocean — which is likely the most habitable part of Europa because it's warmer and it's protected ... to come out above the ice shell," she added.
University of Michigan space physicist Xianzhe Jia led the latest study, which was published in the journal Nature Astronomy.
The findings support other evidence of plumes from Europa, whose ocean may contain two times as much water as all of Earth's oceans. In 2012, NASA's Hubble Space Telescope collected evidence of ultraviolet radiation which suggests a plume.
NASA will get a close-up look from a new spacecraft as part of the space agency's Europa Clipper mission. That spacecraft could be launched as soon as June 2022. The agency says this could provide a chance to examine plumes for signs of life from Europa's ocean, some of which may be microscopic.
Experts consider Europa to be among the top candidates for life in our solar system. But it is not the only one.
For example, NASA's Cassini spacecraft examined plumes from Enceladus, a moon of the planet Saturn. The water from Enceladus's ocean contained hydrogen from hydrothermal vents, an environment that may have given rise to life on Earth.
Europa is a little smaller than Earth's moon. Its ocean is buried under about 15 to 25 kilometers of ice. Experts believe the ocean itself to be anywhere from 60 to 150 kilometers deep.
I'm Pete Musto.
Will Dunham first reported this story for the Reuters news service. Pete Musto adapted his report for VOA Learning English. George Grow was the editor.
What do you think scientists will find in Europa's oceans? Write to us in the Comments Section or on 51VOA.COM.
Words in This Story
data – n. facts or information used usually to calculate, analyze, or plan something
geyser – n. a hole in the ground that shoots out hot water and steam
plume – n. something, such as smoke, steam, or water, that rises into the air in a tall, thin shape
habitability – adj. the ability of a place or location to support life
exciting – adj. causing feelings of interest and enthusiasm
detection – n. the act or process of discovering, finding, or noticing something
journal – n. a magazine that reports on things of special interest to a particular group of people
mission – n. a task or job that someone is given to do
solar system – n. our sun and the planets that move around it
hydrothermal vent(s) – n. an opening in a planet's surface from which naturally heated water issues