The Large Binocular Telescope (LBT), located on Mount Graham in Arizona and operated by the University of Arizona, is part of the next generation of extremely large telescopes (ELTs). With two primary mirrors measuring 8.4 m (~27.5 ft), it has a slightly larger collection area than a 30 meter (98.4 ft) telescope. With their resolution, adaptive optics and sophisticated instruments, these telescopes are expected to probe deeper into the Universe and provide stunning images of everything from distant galaxies to objects in our solar system.
An international team led by the University of Arizona recently acquired images of Jupiter’s moon Io, which constitute the highest resolution images ever taken by a ground-based telescope. The images revealed surface features measuring just 80 km (50 mi), a spatial resolution previously reserved for spacecraft. This includes NASA’s Juno mission, which captured some of the most stunning images of Io’s volcanoes. These images were made possible thanks to LBT’s new SHARK-VIS instrument and the telescope’s adaptive optics system.
The team was led by Al Conrad, an associate scientist in the University of Arizona Department of Astronomy, Stewart Observatory and the Large Binocular Telescope Observatory (LBTO). He was joined by researchers from the University of California at Berkeley, the California Institute of Technology and NASA’s Jet Propulsion Laboratory. Their paper, “Observation of Io’s Resurfacing via Plume Deposition Using Ground-Based Adaptive Optics at Visible Wavelengths With LBT SHARK-VIS (GRL),” and the LBT images are expected to be published in the Geophysical research letters.
SHARK-VIS is a high-contrast optical coronagraphic imaging instrument designed and built at the INAF-Osservatorio Astronomico di Roma. The instrument is powered by the refurbished LBT Extreme Adaptive Optics system, called the Unique Conjugate Adaptive Optics Upgrade for LBT (SOUL). It was installed in 2023 on the LBT with the SHARK-NIR near-infrared instrument, to take advantage of the telescope’s exceptional adaptive optics system. The key to the instrument is its fast, ultra-low-noise “rapid imaging” camera that captures slow-motion images that freeze out optical distortions caused by atmospheric interference.
Gianluca Li Causi, head of SHARK-VIS data processing at the Italian National Institute of Astrophysics, explained how it works in a recent press release from the University of Arizona:
“We process our data on a computer to remove any trace of the electronic fingerprint of the sensor. We then select the best frames and combine them using highly efficient software called Kraken, developed by our colleagues Douglas Hope and Stuart Jefferies at Georgia State University. Kraken allows us to remove atmospheric effects, revealing Io in incredible clarity.
The SHARK-VIS image was so rich in detail that it allowed researchers to identify a major resurfacing event around Pele, one of Io’s largest volcanoes located in the southern hemisphere near the equator (and named after the Hawaiian deity associated with fire and volcanoes). . The image shows a plume deposit around Pele covered by eruption deposits from Pillan Patera, a nearby volcano. NASA’s Galileo space probe observed a similar flare sequence during its exploration of the Jupiter system between 1995 and 2003. However, this was the first time an Earth-based observatory had taken such detailed images.
“We interpret the changes as dark lava deposits and white sulfur dioxide deposits from an eruption at Pillan Patera, which partially cover the red, sulfur-rich Pelé plume deposit,” said co-author Ashley Davies, senior scientist at NASA’s Jet Propulsion Laboratory. . “Before SHARK-VIS, such resurfacing events were impossible to observe from Earth.” Io is the innermost of Jupiter’s largest moons (aka Galilean moons), which include Europa, Ganymede, and Callisto. Ever since NASA’s Voyager 1 space probe flew past the Jupiter system in 1979, scientists have been fascinated by Io and its volcanic features.
Along with Europa and Ganymede, Io is locked in a 1:2:4 orbital resonance, where Europa makes two orbits for every orbit made by Ganymede, and Io makes four. Between its interaction with these moons and Jupiter’s powerful gravity, Io’s interior is constantly flexing, producing hot lava that erupts across the surface. Although telescopes have taken infrared images revealing hot spots caused by eruptions, they are not sharp enough to reveal surface details or identify eruption locations. By monitoring eruptions on Io’s surface, scientists hope to better understand the tidal heating mechanism responsible for Io’s intense volcanism.
“Io therefore presents a unique opportunity to learn more about the powerful eruptions that helped shape the surfaces of the Earth and the Moon in the distant past,” Conrad said. Studies like this, he added, will help researchers understand why some planets have active volcanoes while others do not. For example, while Venus is thought to still be volcanically active, Mars is home to the largest volcanoes in the solar system, but it is inactive. These studies could also one day shed light on volcanic exoplanets, helping astronomers identify geological activity on distant planets (a possible indication of habitability).
SHARK-VIS instrument scientist Simone Antoniucci predicts that it will enable new observations of objects throughout the solar system with similar sharpness, revealing all kinds of features that would otherwise require a spacecraft. “The acute vision of SHARK-VIS is particularly suited to observing the surfaces of many bodies in the solar system, not only the moons of giant planets but also asteroids,” he said. “We already have some observed some, with the data currently being analyzed, and plan to observe more.”
Further reading: University of Arizona