by The most volcanic body in the solar system, Jupiter’s moon Io, has been in turmoil for at least 4.57 billion years, right back to its birth and the beginning of the sun.
These are the results of a team of scientists who examined Io with the Atacama Large Millimeter/Sub-millimeter Array (ALMA) to trace sulfur and chlorine in the Jovian moon’s atmosphere.
Scientists have realized that the gravitational tug of war between Jupiter and the neighboring Jovian moons Europa and Ganymede creates enormous tidal forces within Io that cause its intense volcanism. What was not clear until now was how long the influence of Jupiter and its moons was destroying Io. That’s because a constant flow of lava from this large volcano across its surface keeps this moon looking fresh.
Related: NASA’s Juno probe sees active volcanic eruptions on volcanic moon Io Io (images)
“The surface of Io is very young,” meaning that the lava flows and volcanic ash deposits cover any features older than about 1 million years,” Katherine de Kleer, team leader and Assistant Professor of Planetary Science and Astronomy at Caltech, said Space.com. “Thus, nothing had previously been learned about Io’s volcanic history in the past million years, which is geologically extremely short.
“Io has been a great mystery because its surface does not have a record of its history as do the surfaces of less active moons.”
The atmosphere of Io age cannot hide its volcanism
Io’s extreme volcanism depends on the precise placement of the three moons and the rhythmic gravitational dance in which they orbit Jupiter.
“Io is in resonance orbit with Europa and Ganymede, which means that their orbital periods are multiples of each other,” said de Kleer. For every four orbits of Io, there are exactly two orbits of Europa and one orbit of Ganymede. This means that the moon’s gravitational influence on each other is at the same point each orbit, tweaking the orbits from circles into ellipses.”
She said that as these moons are in an ellipse, their distance from Jupiter changes as they go around, and their gravity from Jupiter changes. The change in Jupiter’s gravity felt by Io causes rock tides on the moon, and Io’s shape is compressed and stretched out each orbit, which is only 1.8 days. This generates friction in its mantle, which produces enough heat to melt rock.
The gravitational pull and push of Jupiter, Europa, and Ganymede on Io generate tidal forces so intense that they can cause the moon’s surface to rise and fall as much as 330 feet (100 meters). That’s the equivalent of the Earth’s surface in New York suddenly jumping up over the top of the Statue of Liberty.
The big question is: Has this been happening for as long as these moons have existed?
“Computer simulations published over the past 20 years have shown that Io, Europa, and Ganymede may have been trapped in their current resonant orbital configuration during their formation,” continued de Kleer. “This resonance is what ultimately causes volcanism. Therefore, it makes sense that if the moons were in this configuration from the time of their formation, Io would be volcanic for that same period.”
Because scientists were unable to get information on how long Io was extremely volcanic, de Kleer and his colleagues used ALMA, an array of 66 radio antennas in the Atacama desert in Northern Chile, to look for clues. in its thin atmosphere.
In particular, they looked for stable isotope radios of molecules containing sulfur and chlorine. The team found that both elements are more present in variants of heavy isotopes – atoms with a higher number of neutrons – compared to the average value found throughout the solar system resulting from lighter isotopes from atmospheres the cream of the other world.
On Io, volcanism causes material to continually recycle between the moon’s interior and its atmosphere, and as a result de Kleer and crew discovered, the Jovian moon has lost as much as 94% to 96% to lose its lighter sulfur isotope. This is something that would only be possible against billions of years of volcanism dating back to the birth of Io.
“We used sulfur isotopes in Io’s atmosphere to determine that Io has been producing sulfur-rich gas – and, therefore, has been volcanically active – for billions of years,” said de Kleer. “This is a nice confirmation of some previous predictions.”
For de Kleer, the results show long-term interest in Io providing answers to nagging questions.
“I’ve been interested in the question of Io’s long-term evolution for as long as I’ve studied Io,” she said. “I’m interested not only in what planets and moons are like today but how they got to be what they are.”
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And the Caltech professor isn’t done with Io yet, either. After answering questions about the fiery nature of the Jovian moon, she wants to know if there was ever a cooler element and if this was destroyed by its volcanism.
“Next, I’d love to know if Io once had a water ocean and ice crust, like its neighbors Europa and Ganymede, which were later lost through volcanism or some other means,” said de Kleer concluded.
The team’s research was published Thursday (April 18) in the journal Science.
