IMAGE PROCESSING GALLERY
One of the biggest challenges for Juno is Jupiter's intense radiation belts, which are expected to limit the lifetime of both Juno’s engineering and science subsystems. JunoCam is now showing the effects of that radiation on some of its parts. PJ56 images show a reduction in our dynamic range and an increase in background and noise. We invite citizen scientists to explore new ways to process these images to continue to bring out the beauty and mysteries of Jupiter and its moons.
For those of you who have contributed – thank you! Your labors of love have illustrated articles about Juno, Jupiter and JunoCam. Your products show up in all sorts of places. We have used them to report to the scientific community. We are writing papers for scientific journals and using your contributions – always with appropriate attribution of course. Some creations are works of art and we are working out ways to showcase them as art.
We have a methane filter, included for the polar science investigation, that is almost at the limits of our detector’s wavelength range. To get enough photons for an image we need to use a very long exposure. In some images this results in scattered light in the image. For science purposes we will simply crop out the portions of the image that include this artifact. Work is in progress to determine exactly what conditions cause stray light problems so that this can be minimized for future imaging.
The JunoCam images are identified by a small spacecraft icon. You will see both raw and processed versions of the images as they become available. The JunoCam movie posts have too many images to post individually, so we are making them available for download in batches as zip files.
You can filter the gallery by many different characteristics, including by Perijove Pass, Points of Interest and Mission Phase. If you have a favorite “artist” you can create your own gallery. Click on “Submitted by” on the left, select your favorite artist(s), and then click on “Filter”.
A special note about the Earth Flyby mission phase images: these were acquired in 2013 when Juno flew past Earth. Examples of processed images are shown; most contributions are from amateurs.
The spacecraft spin rate would cause more than a pixel's worth of image blurring for exposures longer than about 3.2 milliseconds. For the illumination conditions at Jupiter such short exposures would result in unacceptably low SNR, so the camera provides Time-Delayed-Integration (TDI). TDI vertically shifts the image one row each 3.2 milliseconds over the course of the exposure, cancelling the scene motion induced by rotation. Up to about 100 TDI steps can be used for the orbital timing case while still maintaining the needed frame rate for frame-to-frame overlap. For Earth Flyby the light levels are high enough that TDI is not needed except for the methane band and for nightside imaging.
Junocam pixels are 12 bits deep from the camera but are converted to 8 bits inside the instrument using a lossless "companding" table, a process similar to gamma correction, to reduce their size. All Junocam products on the missionjuno website are in this 8-bit form as received on Earth. Scientific users interested in radiometric analysis should use the "RDR" data products archived with the Planetary Data System, which have been converted back to a linear 12-bit scale.
Juno Images of Io from April 9
The Juno spacecraft flew by Io on April 9 at a distance of 106,000 kilometers its way to its 41st perijove. This is Juno's closest encounter of Io so far in its nearly six year mission, and the closest encounter with Io by any spacecraft since Galileo flew by in November 2002. The JunoCAM camera acquired these five images of Io during the encounter over a period of nearly an hour, with the first image being taken 8 minutes before closest approach and the last being taken 50 minutes after closest approach. The original pixel scales range from 72 kilometers per pixel for the upper left and upper center image to 91 kilometers per pixel in the lower right image. All images have been magnified by 5x to increase visibility of features using a simple nearest neighbor enlargement to reduce over-interpretation. All images are a combination of red, green, and blue filter framelets.
No apparent major surface changes or plumes can be seen in these images but even at 70 km/pixel, large-scale surface features can be seen across Io's northern trailing hemisphere. In the bottom left image, three mountains can be seen along the terminator, the boundary between Io's night and day sides, poking up on the dark side of the terminator.
Juno's next "Voyager-class" encounter with Io takes place on July 5 at a distance of 86,000 kilometers. Juno will perform several more encounters with Io over the next year and a half culminating in a pair of 1,500 km altitude flybys in late 2023 and early 2024.
