It’s been over twenty-two years since we’ve been able to see Jupiter’s enticing moon Europa close-up. But now the Juno spacecraft has made its closest pass of Europa, sending back some amazing pictures of the icy mini-world, which likely has an ocean that contains more water than all of Earth’s oceans combined.
Observations from the spacecraft’s 45th orbit around Jupiter brought it close enough to give us some of the best views of Europa that we’ve ever had.
In July 2016, NASA’s Juno space probe reached Jupiter, becoming the second spacecraft in history to orbit the gas giant (the first being the Galileo probe that orbited Jupiter from 1995 to 2003). The data it has sent back has led to new revelations about the Jovian atmosphere, magnetosphere, gravitational field, structure, and composition. While its primary mission was intended to only last until 2018, a mission extension means that Juno will continue to orbit Jupiter’s poles (a perijove maneuver) and send back stunning images and data until 2025.
Recently, a team of citizen scientists led by mathematician and software developer Gerald Eichstädt used images taken by the probe’s visible-light camera/telescope (the JunoCam) to create a 3D animation of Jupiter’s upper atmosphere. Eichstädt’s animation was presented at the 2022 Europlanet Science Congress (EPSC), which took place from September 18 – 23 in Granada, and shows the relative heights of the cloud tops of Jupiter that reveal delicately textured swirls and peaks. Eichstädt’s work also showcased the potential for citizen science and public engagement with today’s missions.
This next week will mark a scientifically valuable achievement for NASA’s Juno mission, as the pioneering spacecraft is slated to fly within 358 kilometers (222 miles) of Jupiter’s icy moon Europa on September 29 at 5:36 a.m. EDT (2:36 a.m. PDT) as part of its extended mission to explore the Jupiter system. A flyby this close to Europa’s surface will allow Juno to acquire some of the highest-resolution images ever taken of the icy moon. For context, the last mission to explore Europa in depth was NASA’s Galileo spacecraft, which got within 351 kilometers (218 miles) of the surface on January 3, 2000.
Jupiter is composed almost entirely of hydrogen and helium. The amounts of each closely conform to the theoretical quantities in the primordial solar nebula. But it also contains other heavier elements, which astronomers call metals. Even though metals are a small component of Jupiter, their presence and distribution tell astronomers a lot.
According to a new study, Jupiter’s metal content and distribution mean that the planet ate a lot of rocky planetesimals in its youth.
On May 23, 2022, the Juno spacecraft made another close pass of Jupiter, with its suite of scientific instruments collecting data and its JunoCam visible light camera snapping photos all the while. This close pass, called a perijove, is the 42nd time the spacecraft has swung past Jupiter since Juno’s arrival in 2016.
What is that large dark smudge on Jupiter’s side? It may remind you of a certain scene from the sci-fi film “2010: The Year We Make Contact,” where a growing black spot appears in Jupiter’s atmosphere.
But this is a real photo, and the dark spot is just an elongated shadow of Ganymede, Jupiter’s largest moon. Just like when Earth’s Moon crosses between our planet and the Sun creating an eclipse for lucky Earthlings, when Jupiter’s moons cross between the gas giant and the Sun, they create shadows too.
In addition, the Juno mission has allowed astronomers to learn more about how magnetic interaction between some of Jupiter’s moons and its atmosphere leads the gas giant to experience aurorae around its northern and southern poles. After analyzing data from Juno’s payload, a team of researchers from the Southwest Research Institute (SwRI) observed how streams of electrons from Ganymede (Jupiter’s largest moon) leave an “auroral footprint” in Jupiter’s atmosphere.
As originally planned, Juno’s 37th close pass by Jupiter – called Perijove 37 – would have been its last. Per the original mission outline, the Juno spacecraft would have been programed to plunge into Jupiter on Perijove 37 as a mission-ending self-sacrifice. Destroying Juno would protect the Jovian moons — especially Europa — from potential future contamination by an unpowered spacecraft wandering adrift through the Jupiter system. As careful as NASA is about taking precautions to limit the amount of Earth-sourced biological material carried by robotic spacecraft, it’s incredibly difficult to ensure that no microbes might have tagged along.
But, back to Juno: as it stands now, the Juno mission is just getting started. With a mission extension granted earlier this year, Juno will continue to operate until at least 2025, with 42 extra orbits added to the mission.
And thank goodness, because the images from Perijove 37 are pretty stunning. The new mission plan put Juno on a relatively close pass to image Jupiter itself, as well as a great view of Jupiter’s moon Europa, see below.
During Juno’s extended mission, every orbit is like a new adventure. Each orbit is a little different, and NASA says the natural evolution of Juno’s orbit around Jupiter provides a wealth of new science opportunities.
But for most of us, what we look forward to on every perijove – the point in each orbit where the Juno spacecraft comes closest to the gas giant – are the incredible images taken by the camera on board, JunoCam. As Juno’s “eyes,” the camera provides a unique vantage point no other spacecraft has been able to give us.