JunoCam: The Little Camera That Could

Jupiter and Galilean moon Io, by JunoCam, Juno spacecraft (Jupiter Orbit 53, processed by Alain Mir)

One day the goddess Juno perceived that it suddenly grew dark, and immediately suspected that her husband, Jupiter, had raised a cloud to hide some of his doings that would not bear the light. She brushed away the cloud, and saw her husband, on the banks of a glassy river, with a beautiful heifer standing near him. Juno suspected that the heifer’s form concealed some fair nymph of mortal mould. This was indeed the case; for it was Io, the daughter of the river god Inachus, whom Jupiter had been flirting with. – Bulfinch, The Age of Fable, Chapter IV.

Juno, the spacecraft, was designed to peer through the deep clouds of the planet Jupiter, to see what was going on deep in the planet’s atmosphere, even down to the core. Launched in 2011, and achieving a polar orbit around Jupiter in 2016, Juno has accomplished her original mission. Designed with the hope she could remain operation through as many as 8 orbits in Jupiter’s ferocious magnetic and radiation fields, she is now into her 53rd orbit and has been repurposed to explore the Galilean moons, the first close-up spacecraft visit to the Galilean moons since spacecraft Galileo in 1995-2003.

Colorized and sharpened image of Jupiter by JunoCam, spacecraft Juno (Jupiter Orbit 53, by Tanya Oleksui)

Almost as an afterthought in Juno’s design, one of the instruments is the JunoCam, a digital camera. The camera’s sensor is a KODAK KAI-2020, capable of color imaging at 1600 x 1200 pixels: less than 2 megapixels. The comparatively small resolution – WC’s over-the-counter digital camera has a resolution of 45 megapixels – is more a function of the limited bandwidth to transmit images back to earth. Juno’s total bandwidth is 325 pixels per second; image data has to share that tiny bandwidth with the data from the science instruments. Juno’s polar orbit was slightly altered to bring the spacecraft close to the four Galilean moons.

In a delightful analogy to the classical myth that gave spacecraft Juno her name, the spacecraft and JunoCam are now targeting Io, the most volcanically active body in our solar system. In fact, dramatic changes in the face of Io have already been identified just since spacecraft Galileo flew by 20 years earlier. The Ioan volcano Prometheus is apparently still erupting.

Io from about 13,700 miles, by JunoCam, spacecraft Juno (processed by Alain Mir)

The orbital mechanics are a little complex, but over the next two years Juno’s 53 day polar orbits of Juno around Jupiter will come much closer to Io. Perijovian Orbit 53 brought Juno and JunoCam within 13,700 miles of the surface of Io. On December 30, 2023 and February 3, 2024, Juno will make flybys coming within 930 miles of that moon. If the beautiful heifer is there, JunoCam may photograph it.

Io as spacecraft Juno approached and then moved past the moon, by JunoCam, spacecraft Juno (processed by Jason Perry)

The JunoCam part of the Juno mission is led by Candice Hansen-Koharcheck. Congratulations to Dr. Hansen-Koharcheck on a stunningly successful mission, and to the entire Juno engineering and projects teams. WC can hardly wait for the next images.

Congratulations too to the citizen scientists who have processed the image data from JunoCam. Their work is available for public viewing (WARNING: serious time suck) and the raw data is available if you want to sign up to do some citizen science yourself.

Let’s hear it for JunoCam, the little camera that could.

This post was inspired by the criticisms WC received for suggesting the Kodiak Spaceport was a classic Sunk Cost Fallacy. For the record, the rocket carrying Juno was launched from Cape Canaveral.

Geology, photography, technogeekery and classic literature, all in one post. The Magpie Principle in all its glory.