Jupiter's Moons: Mapping Io's volcanic heat

The most active volcanic body in the Solar System is not playing ball with scientists, as new mysteries emerge surrounding the internal heating of the moon Io.

A new study on Jupiter’s moon Io has yielded a map of hot spots which show the range of heat being emitted by the highly active volcanic body.

The volcanic eruptions on Io are immense, and dwarf the volcanic activity seen on Earth.

The volcanic activity of Io gives it its yellow surface colour which is frozen sulphur.

Io’s extravagant volcanism comes as a result of tidal interactions with the giant planet Jupiter and a complex orbital interplay between Europa, Ganymede and the parent planet.

Io’s slightly elliptical orbit around Jupiter means that the direction of the tidal bulge is constantly changing, effectively stirring up the molten material within the moon.

"The fascinating thing about the distribution of the heat flow is that it is not in keeping with the current preferred model of tidal heating of Io at relatively shallow depths," said Ashley Davies from NASA’s Jet Propulsion Laboratory "Instead, the main thermal emission occurs about 40 degrees eastward of its expected positions."

Hot spots on Jupiter's moon Io. Larger spots correspond with greater areas of thermal emission. Credit: NASA/JPL-Caltech/Bear Fight Institute
 
The unusual pattern of the heat distribution suggests that there are complex heating processes deep within the Jovian moon.

"What we see indicates a mixture of both deep and shallow heating," said JPL’s Dennis Matson.

Another oddity that emerged from the study is that the volcanic activity only accounts for 60 per cent of the heat that emanates from Io.

"We are investigating the possibility that there are many smaller volcanoes that are hard, but not impossible, to detect," said Glenn Veeder of the Bear Fight Institute. "We are now puzzling over the observed pattern of heat flow."

Connecting the dots between Io’s internal heating and thermal emission will also help to further understand another Jovian moon, Europa, which could potentially harbour life in the oceans beneath its surface.

The study used data from NASA’s Voyager and Galileo missions, as well as using infrared telescopes on Earth. Galileo was a mission to Jupiter that launched in 1989 was the first to directly measure the gas giant’s atmosphere.

The Galileo probe was deliberately destroyed in Jupiter’s crushing atmosphere in 2003 to avoid a collision with the potentially life bearing moon Europa.