A NASA spacecraft last week took a major step to help scientists gain deeper insight soon into Jupiter’s volcanic moon, Io.

Juno flew by the Jovian moon Io on May 16 in the spacecraft’s closest approach to the moon yet.

The Juno spacecraft was originally launched atop the Atlas V rocket in August 2011 to explore the gas giant Jupiter and its satellites. The probe embarked on a five-year journey, arriving at Jupiter in July 2016.

This craft has so far been in orbit around Jupiter for six years.

While Juno’s primary purpose is to study Jupiter, it also features a number of devices, such as the Jovian InfraRed Auroral Mapper (JIRAM), Stellar Reference Unit (SRU), and the Microwave Radiometer (MWR), that will allow the craft to study Io’s volcanism.

Matthew Johnson of NASA’s Jet Propulsion Laboratory in Southern California said in a press release that the moon has long been of interest to study.

“As well as continuously changing our orbit to allow new perspectives of Jupiter and flying low over the nightside of the planet, the spacecraft will also be threading the needle between some of Jupiter’s rings to learn more about their origin and composition,” said Johnson.

Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, said that Io is the most volcanically active body in the solar system that scientists are aware of.

“By observing it over time on multiple passes, we can watch how the volcanoes vary – how often they erupt, how bright and hot they are, whether they are linked to a group or solo, and if the shape of the lava flow changes,” said Bolton in a press release.

Juno has already passed above Jupiter 50 times and collected data on other Jovian moons, such as Europa and Ganymede. This 51st flyby is its closest to Io ever, passing just over 22,000 miles above the surface, according to NASA.

Bolton said that the set of data from this latest approach will be “amazing.”

“We are entering into another amazing part of Juno’s mission as we get closer and closer to Io with successive orbits. This 51st orbit will provide our closest look yet at this tortured moon,” said Bolton, according to NASA.

“Our upcoming flybys in July and October will bring us even closer, leading up to our twin flyby encounters with Io in December of this year and February of next year, when we fly within 1,500 kilometers of its surface. All of these flybys are providing spectacular views of the volcanic activity of this amazing moon,” he continued.