IMAGE PROCESSING GALLERY
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. I 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.
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”. For other tips about the gallery click on the “Gallery Organization” tab.
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.
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.
Eight views of Io from Perijove 51
On May 16, 2023, Juno passed within 35,000 kilometers of Io's surface. JunoCAM acquired these eight views over a period of an hour and fifteen minutes as the spacecraft approached and receded from Jupiter’s volcanic moon. These are the sharpest visible-light images of Io acquired since the New Horizons flew past Jupiter on its way to Pluto in 2007. They reveal a landscape of mountains and volcanoes, some revealing changes over the course of sixteen years and others revealed due to the unique lighting and viewing geometry of Juno’s flybys.
Several surface changes are visible compared to images taken by New Horizons sixteen years ago and Galileo more than twenty years ago. Some were seen in previous Juno encounters such as fresh red material surrounding Chors Patera and a darkening at a volcano east of Girru Patera. Revealed for the first time in these images are changes at the volcano Volund. Thermal data from the JIRAM instrument, also onboard Juno, in previous encounters of Io showed two prominent areas of activity at Volund on its northwest end and to the west of a circular feature thought to be the vent area of Volund. Both these areas are now darker than they appeared in New Horizons LORRI images. These two dark areas are best seen as the upper two dark spots near the terminator (the boundary between day and night sides) in the middle of the third image from left in the top row. Images from encounters in July and October may help to reveal how these two changes are connected.
The polar geometry of Juno’s encounters is helpful for mapping the terrain in Io’s north polar region. For example, a triangle patch of three bright regions, best seen above center in the second image from left in the bottom row, is revealed to be host to two mountains, one with a height of approximately 5 kilometers. Mountains in Io’s polar regions, like Haemus Montes, are often surrounded by moats of bright sulfur dioxide frost, and these two mountains appear similar. Confirmation of a third mountain will need to wait for imaging from the July and October encounters.
The Io images show here have an original pixel scale of 24 to 52 kilometers per pixel and have been enlarged by 5x to improve the visibility of surface features.
