Perijove 55 Io Flyby in Full HD and 30-Fold Time-Lapse, Reconstructed From JunoCam Data

2023-10-30 01:20 UT
Credit : NASA / JPL / SwRI / MSSS / SPICE / Gerald Eichstädt © cc by
Submitted By : Maquet-80
Mission Phase : PERIJOVE 55

On 2023 OCT 15, 10:52:50 UT, NASA's Juno spacecraft successfully made its Perijove 55 Jupiter flyby.

This video uses 19 of the raw Perijove 55 JunoCam images together with SPICE trajectory data to reconstruct the 105 minutes from 2023-10-15T06:00:00.000 to 2023-10-15T07:45:00.000 when Juno flew by Jupiter's volcanic moon Io just a few hours before closest approach to Jupiter.

The video is blended from scenes, each scene rendered from one of the raw JunoCam images. For each scene, the respective undelying raw JunoCam image was rendered to a sequence of stills, with each still reprojected to a camera position along Juno's trajectory according to SPICE kernels. Assumed camera positions correspond to spacecraft trajectory positions in time steps of 1 second.

The sequence of blended stills was finally converted to an MP4 file using the ffmpeg tool. The stills themselves were rendered from the raw data using a home-made and proprietary software.

The camera appears to change it's overall spectral quantum efficiency over time and presumably mostly due to Jupiter's harsh radiation environment, generally resulting in a gradually increasing reddish cast in the images if keeping color calibration constant. Therefore, it's relevant to provide the adjusted and applied linear radiometric factors used for balancing colors. This video used a constant set of relative radiometric factors derived from the PJ 54 flyby. The applied factors are (0.734; 1.0; 3.023) for (red;green;blue) respectively.

After linearizing the raw data with subsequent radiometric adjustment, the stills were gamma-stretched to the square-root of linear radiometric data. Overall, the resulting colors should be not identical but fairly close to the colors the majority of unaided human eyes would see.

Unlike for most Jupiter images and videos, Io is sufficiently rich in contrast that acceptable images can be achieved without color and brightness stretching.

Rememeber that the Juno mission can only be successful with a team effort, involving a very skilled professional staff acting in the background.