CLUES HIDDEN in data gathered by NASA‘s Galileo spacecraft over 20 years ago may prove that it the spacecraft through a water plume from Jupiter’s moon Europa.
The discovery comes as scientists re-examine the data collected by NASA’s Galileo spacecraft in 1997.
NASA said the findings provides evidence that the Jupiter moon’s subsurface liquid water reservoir may be venting plumes of water vapour above its icy shell.
If true, it could bring new insights to the tantalising question of whether Jupiter’s moon Europa has the ingredients to support alien life.
The new and advanced computer examinations unearth what NASA call a mystery in the data: a “brief, localised bend in the magnetic field”.
While previous ultraviolet images from NASA’s Hubble Space Telescope in 2012 suggested the presence of plumes, the anomaly had gone unexplained until now.
However, the new analysis used data collected much closer to the source and is considered strong, corroborating support for plumes.
The research was led by space physicist at the University of Michigan, Xianzhe Jia. Jia’s team was inspired to dive back into the Galileo data after a member of the Europa Clipper science team, Melissa McGrath, delivered a presentation highlighting other Hubble observations of Europa.
“The data were there, but we needed sophisticated modelling to make sense of the observation,” Jia said.
“One of the locations she mentioned rang a bell. Galileo actually did a flyby of that location, and it was the closest one we ever had. We realised we had to go back.
“We needed to see whether there was anything in the data that could tell us whether or not there was a plume.”
When they examined the information gathered during the flyby some 21 years ago, magnetometer data showed a bend in the magnetic field. Until now that had not been explained. However, they knew this had to be evidence of a plume because previous missions have proven that material in plumes becomes ionised, leaving a “characteristic blip” in the magnetic field.
The team also visited a measurement Galileo carried out during its quest: a powerful Plasma Wave Spectrometer, which measures plasma waves caused by charged particles in gases around Europa’s atmosphere.
That data also appeared to back the theory of a plume.
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“There now seem to be too many lines of evidence to dismiss plumes at Europa,” said Europa Clipper project scientist, Robert Pappalardo.
“This result makes the plumes seem to be much more real and, for me, is a tipping point. These are no longer uncertain blips on a faraway image.”
The full findings will appear in Monday’s issue of the journal Nature Astronomy.