The 1st Close-Up of a Lava Lake on Jupiter’s Moon Io -The Volcanic Epicenter of the Solar System

 

 

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With the first detailed observations through imaging interferometry of a lava lake on Io, a moon of Jupiter and the volcanic epicenter of our Solar System, the Large Binocular Telescope Observatory places itself as the forerunner of the next generation of Extremely Large Telescopes. Io, the innermost of the four moons of Jupiter discovered by Galileo in January 1610, is only slightly bigger than our own Moon but is the most geologically active body in our solar system. Hundreds of volcanic areas dot its surface, which is mostly covered with sulfur and sulfur dioxide.


The largest of these volcanic features, named Loki after the Norse god often associated with fire and chaos, is a volcanic depression called patera in which the denser lava crust solidifying on top of a lava lake episodically sinks in the lake, yielding a rise in the thermal emission which has been regularly observed from Earth. Loki, only 200km in diameter and at least 600 million km from Earth, was, up to recently, too small to be looked at in detail from any ground based optical/infrared telescope.

With its two 8.4 m mirrors set on the same mount 6 m apart, the Large Binocular Telescope (LBT), by combining the light through interferometry, provide images at the same level of detail a 22.8 m telescope would reach. Thanks to the Large Binocular Telescope Interferometer (LBTI), an international team of researchers was able to look at Loki Patera, revealing details as never before seen from Earth; their study is published today in the Astronomical Journal (link here).

"We combine the light from two very large mirrors coherently so that they become a single, extremely, large mirror,” says Al Conrad, the lead of the study and a Scientist at the Large Binocular Telescope Observatory (LBTO). “In this way, for the first time we can measure the brightness coming from different regions within the lake."

 

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The LBT image above of Loki Patera (orange ) laid over a Voyager image of the volcanic depression.The emission (in orange color) appears spread out in the north-south direction due to the telescope point-spread function; it is mainly localized to the southern corners of the lake. (LBTO- NASA). A raw LMIRcam image of Io below shows the fringes on Loki Patera (bright spot) and on fainter active volcanic areas.

LMIRcam, the camera recording the images at the very heart of LBTI in the 3 to 5 micrometers near-infrared band, was the thesis work of Jarron Leisenring as graduate student at the University of Virginia. For Leisenring, now an instrument scientist for NIRCam (the Near InfraRed CAMera for the James Webb Space Telescope) at Steward Observatory, "these observations mark a major milestone for me and the instrument team. LMIRcam has already been very productive these past few years; now, interferometric combination provides the last step in harnessing LBTI’s full potential and enabling a whole host of new scientific opportunities."

"Two of the volcanic features are at newly-active locations", explains Katherine de Kleer, a graduate student at the University of California at Berkeley. "They are located in a region called the Colchis Regio, where an enormous eruption took place just a few months earlier, and may represent the aftermath of that eruption. The high resolution of the LBTI allows us to resolve the residual activity in this region into specific active sites, which could be lava flows or nearby eruptions."

"Studying the very dynamic volcanic activity on Io, which is constantly reshaping the moon 's surface, provides clues to the interior structure and plumbing of this moon," remarked team member Chick Woodward of the University of Minnesota, "helping to pave the way for future NASA missions such as the Io Volcano Observer. Io's highly elliptical orbit close to Jupiter is constantly tidally stressing the moon, like the squeezing of a ripe orange, where the juice can escape through cracks in the peel."

Christian Veillet, Director of the Large Binocular Telescope Observatory (LBTO), observes that: "While there is still much work ahead to make the LBT/LBTI combination a fully operational instrument, we can safely state that the Large Binocular Telescope is truly a forerunner of the next generation of Extremely Large Telescopes slated to see first light in a decade (or more) from now."

With plumes of matter rising up to 186 miles (300 km) above the surface, Io is considered a prime candidate as a hotspot for extreme extraterrestrial life.

"Everyone right away tends to categorically exclude the possibility of life on Io," said astrobiologist Dirk Schulze-Makuch at Washington State University. Conditions on Io might have made it a friendlier habitat in the distant past. If life did ever develop on Io, there is a chance it might have survived to the present day, Schulze-Makuch suggested.

"Life on the surface is all but impossible, but if you go down further into the rocks, it could be intriguing," he said. "We shouldn't categorize it as dead right away just because it's so extreme."

Computer models suggest Io formed in a region around Jupiter where water ice was plentiful. Io's heat, combined with the resulting possibility of liquid water, could have made life plausible.

“There must have been quite a lot of water on Io shortly after formation, judging from the amount of water ice on Europa and Ganymede,” said Schulze-Makuch.

Jupiter's radiation would have stripped this water from Io's surface, perhaps within 10 million years. At this point life could have retreated underground, where water might still be abundant, and geothermal activity and sulfur compounds could provide microbes with sufficient energy to survive.

Although no organic molecules have been detected on the moon’s surface, that does not mean they do not exist underground, Schulze-Makuch said. Any organic compounds that once existed on the surface or that may today still emanate from the subsurface — which probably were naturally present in this region of space during Io's formation — would get quickly destroyed by Jupiter's radiation.

The many lava tubes thought to exist on Io could serve as an especially favorable environment for life, Schulze-Makuch suggested, by protecting organisms from radiation. The lava tubes also could provide thermal insulation, trapping moisture and providing nutrients such as sulfurous compounds. Microbes are common in lava tubes on Earth, from ice and volcano zones in Iceland to hot sand-floored tubes in Saudi Arabia, and lava tubes are the most plausible cave environment for life on Mars, he added.

The primordial soup that any life on Io might have originated from was likely based on water, but the solvent of choice for organisms there might have drastically changed later on as the moon transformed. Hydrogen sulfide is one choice, as it is reasonably abundant in Io's shallow subsurface and remains liquid from negative 123 to negative 76 degrees F (-86 to -60 degrees C), falling within the environmental conditions that would prevail there. While it is not especially efficient as a solvent for ions, it does dissolve many substances, including many organic compounds. Other possibilities include sulfur dioxide and sulfuric acid.

"I'm exploring with colleagues whether sulfur compounds could work as solvents of life," Schulze-Makuch noted. Given the wild extremes Io can swing through as it orbits Jupiter, one possible survival strategy for life in this challenging environment would be to remain dormant most of the time, only reverting back when nutrients were rich. "It'd be much easier for life to take a beating if it goes dormant regularly," Schulze-Makuch said.

The Daily Galaxy via University of Arizona, Washington State University, solarsystem.nasa.gov and jpl.nasa.gov

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