Curtains of Fire: Peering into Io’s volcanic Laboratory
“The amount of energy being emitted by these eruptions implies lava fountains gushing out of fissures at a very large volume per second,” said Ashley Davies, a volcanologist with NASA’s Jet Propulsion Laboratory in Pasadena, California, “forming lava flows that quickly spread over the surface of Io.”
Io hosts the first lava-producing volcanoes discovered outside of Earth. However, after their initial discovery in 1979, the eruptions have proved elusive.
The smallest of Jupiter’s Galilean moons and the closest to the gas giant, Io was surveyed by the Galileo spacecraft in the mid-1990’s. Since then, ground-based telescopes have continually provided evidence of recent eruptions. Lava fountains, rivers and lakes have been recorded, but only a handful of actual eruptions have actually been caught in the act. Between 1978 and 2006, only 13 large eruptions were observed. These were picked up by astronomers like Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, who regularly scans Io in the hopes of finding eruptions of just this type.
“We typically expect one huge outburst every one or two years, and they’re usually not this bright,” said de Pater, lead author of one of two papers describing the three large eruptions detected in August 2013
Using the the Keck II telescope, one of two 10-meter telescopes operated by the Keck Observatory, De Pater and her colleagues discovered a pair of massive eruptions on Aug. 15, 2013. The brighter of the two lava flows took place at Rarog Patera – a bowl-shaped depression in Io’s southern hemisphere. That eruption was an estimated 50-square-miles wide (130-square-kilometers) and 30 feet thick (10 meters thick). The smaller of the two covered 120 square miles (310 square kilometers). A third eruption detected on Aug. 29 using the Gemini North telescope on Mauna Kea.
Lava bursting through fissures several miles long at all three sites created massive curtains of fire from magma much hotter than any we have on Earth today. According to de Pater, are much more, “indicative of a composition of the magma that on Earth only occurred in our planet’s formative years.”
According to the authors, intense geologic activity on Io is a window into Earth’s early history, when explosions were more frequent and intense. In the crucible of that far-off yesterday, much of what we see today was formed.
To that end, Davies developed models to predict the volume of magma based on spectroscopic observations of Io’s eruptions. These may, “help us understand the processes that helped shape the surfaces of all the terrestrial planets, including Earth, and the moon.”
Observing various kinds of geologic activity – from volcanoes on Io to geysers on Enceladus-has become an increasing trend in astronomy. It is as if, in discovering more and more planetary systems far away, understanding our own has become increasingly relevant.
“I saw this as a nice opportunity to more closely connect one end of solar system formation/evolution to another,” said David R. Ciardi of the NASA Exoplanet Science Institute/California Institute of Technology. “Understanding our solar system will help understand all the other systems we are finding and vice versa.”
With further searches, de Pater predicts that we will find further fountains of fire in the distance.
“Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io.”