NASA’s Juno has a new mission to explore moons of Jupiter

NASA recently announced that the Juno mission to Jupiter would be extended through 2025. The probe will have a new mission to conduct close flybys of three of Jupiter’s moons, using its suite of instruments to further unlock their secrets in a follow-up to the observations made by the Voyager and Galileo spacecraft.

Juno, the second probe under NASA’s New Frontiers program, was launched in August 2011. After getting a gravity assist flyby of Earth in October 2013, the probe arrived in Jupiter’s space in July 2016. Juno went into a high elliptical polar orbit around Jupiter that took it within 2,600 miles of the gas giant’s poles before going out about five million miles. In this way the probe’s exposure to Jupiter’s intense radiation field was minimized. Each orbit takes around 53 days.

Juno spent the next four years and more examining Jupiter’s solid core, its atmosphere and its magnetosphere, among other aspects of the solar system’s largest planet. The probe returned some of the most hauntingly beautiful images ever returned from space of Jupiter’s poles, hitherto unseen by human beings.  

Originally, the plan was to crash Juno into Jupiter in July 2021 to prevent the probe from becoming space debris. However, the decision to give Juno a new mission will delay that event until 2025.

Juno will pass Ganymede at a distance of 1,000 kilometers later in 2021. Ganymede is the largest moon in the solar system, has its own magnetic field, an outer layer of ice mixed with rock, a rocky mantle, and an iron core. Juno will be able to measure Ganymede’s magnetosphere and examine any changes to the surface that may have happened since the Voyager and Galileo missions.

In late 2022, Juno will fly 320 kilometers past Europa. Europa, the target of the planned Europa Clipper mission, has an icy surface that many scientists believe conceals a warm water ocean, perhaps containing life. Juno will be able to measure the thickness of the ice layer and to confirm if the subsurface ocean actually exists.

Finally, in 2024, Juno will pass Io at a distance of 1,500 kilometers. The moon Io is the most volcanically active body in the solar system. Juno will study volcanic activity comparing what is found with the data from Galileo and Voyager.

New Horizons was the first robotic probe in the New Frontier program. New Horizons conducted a close flyby of Pluto in 2015, the former ninth planet of the solar system, now considered a dwarf planet, as well as its moons. The probe uncovered many secrets of a world that proved to be strange and fascinating. New Horizon is currently passing through the Kuiper Belt in search of new targets of opportunity. The probe has already passed a Kuiper Belt object called Arrokoth, a weird body that looks like two spheres mashed together.

The third probe in the New Frontier program, the Osiris-REx, collected a sample from the asteroid Bennu in October 2020. The probe is due to return to Earth with its scientific treasure in 2023. Bennu is an Earth-approaching, carbonaceous asteroid that has a one in 2,700 chance of colliding with the Earth sometime in the latter 22nd century.

Dragonfly is the fourth planned mission under the New Frontier program. The probe is a nuclear-powered drone that will fly through the nitrogen-methane atmosphere of Titan, a moon of Jupiter. Dragonfly will study the weather and seismology of Titan, but its primary mission will be to search for signs of life on a world where the oceans are composed of liquid methane and ethane. Dragonfly is scheduled to launch in 2026 with an arrival on Titan in 2034.

By repurposing the Juno, NASA has squeezed out two missions for the price of one, similar to how the New Horizon changed from a Pluto flyby to a Kuiper Belt explorer. Space exploration, even that conducted with robotic probes, is so expensive that the cost savings garnered by such a strategy is a testament to the ingenuity of NASA and its commercial and academic partners.

Mark Whittington, who writes frequently about space and politics, has published a political study of space exploration entitled Why is It So Hard to Go Back to the Moon? as well as “The Moon, Mars and Beyond.” He blogs at Curmudgeons Corner. He is published in the Wall Street Journal, Forbes, The Hill, USA Today, the LA Times and the Washington Post, among other venues.