Juno Perijove 48, January 22, 2023 |
Juno Perijove 48, January 22, 2023 |
Jan 28 2023, 04:48 PM
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Senior Member Group: Members Posts: 2511 Joined: 13-September 05 Member No.: 497 |
https://www.nasa.gov/feature/jpl/nasa-s-jun...lyby-of-jupiter
QUOTE The JunoCam imager aboard NASA’s Juno spacecraft did not acquire all planned images during the orbiter’s most recent flyby of Jupiter on Jan. 22. Data received from the spacecraft indicates that the camera experienced an issue similar to one that occurred on its previous close pass of the gas giant last month, when the team saw an anomalous temperature rise after the camera was powered on in preparation for the flyby. However, on this new occasion the issue persisted for a longer period of time (23 hours compared to 36 minutes during the December close pass), leaving the first 214 JunoCam images planned for the flyby unusable. As with the previous occurrence, once the anomaly that caused the temperature rise cleared, the camera returned to normal operation and the remaining 44 images were of good quality and usable. The good images have been posted to missionjuno. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Feb 1 2023, 01:35 AM
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IMG to PNG GOD Group: Moderator Posts: 2250 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Gerald understood correctly what I was saying. However, the real color of the southern hemisphere also isn't identical to the real color of the northern hemisphere and this complicates matters. Also it is getting increasingly difficult to reliably monitor color changes because many of the images now show dimly lit areas near the terminator. This can make possible scattered light, dark current and noise a bigger proportion of the image brightness and this might mess up the color. My main (but not only) 'color reference' has been the whitish South Tropical Zone (STrZ). Getting good color measurements for the STrZ has been getting increasingly difficult due to the increasing phase angle. It is 95° in image PJ48_215, meaning that the STrZ is relatively dimly lit except near the limb. This makes me less confident in the color measurements than I was a few perijoves ago. Nevertheless I think something must have changed now. Using the color correction I used for PJ47, the color of image PJ48_215 is far too red. It is far redder than the color of comparable images at PJ47 or PJ46 when I used the color correction from the previous perijove.
The problem: I'm (almost) sure something has changed significantly at PJ48 compared to PJ47 but I doubt I can prove it (or, in particular, doubt I can prove that it is an instrument change). This "something" that apparently has changed could be e.g. optics, scattered light, filters, sensor or a combination of these. |
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