Something on a NASA photo from Mars [Cosmic Ray]

AmberRobot

Active Member
So just coincidence that they've thus far all appeared on the same camera (afaik)?
What do you mean by “all”? I was told that they are reasonably frequent and was even sent two images with cosmic ray hits as examples (one dark and one light). There are likely many more examples than have been discussed here but I don’t know how exhaustive a search has been done on all images from all cameras for the presence of cosmic ray hits to comment on the relevant statistics.
 

AmberRobot

Active Member
Well, all the ones I've seen were from the right navigation camera.

Others were from different cameras?
I don’t know, but how many are you talking about? With small number statistics there could be more from one than the other but not be a statistically significant difference.
 

Ann K

Senior Member.
Email from Justin Maki, forwarded to me by Linda Kah. Justin is the engineering camera lead for the Mars Science Laboratory mission and a member of the MSL Science Camera Team.


Hi Linda –

That is a textbook cosmic ray!

In this particular case the cosmic ray appears dark rather than bright because the cosmic ray hit the detector during a bias (shutter) frame acquisition. The shutter image is subtracted from the image of interest, producing a low pixel DN (digital number) value, i.e., a dark smudge.

Note that dark smudges are also sometimes due to physical debris on the detector (e.g., WATSON and MAHLI). But in this particular case it is definitely a cosmic ray.

Cosmic rays come in all sort of styles – most of them are due to protons, i.e., ionized hydrogen. The length and shape of the cosmic ray streaks depend on the angle at which the cosmic ray hits the detector. Cosmic rays are fascinating btw.

Cosmic ray hits are actually pretty common – most go unnoticed, unless they appear in the sky.

Examples attached, and links below:
Cosmic ray examples (mostly nighttime images):

https://photojournal.jpl.nasa.gov/catalog/PIA05551
https://photojournal.jpl.nasa.gov/catalog/pia06337
https://www.space.com/mars-insight-meteor-photographs-cosmic-rays.html

Hope this helps!
Content from External Source
 
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Ann K

Senior Member.
Email today from Justin Maki. The Mars people are all familiar with the blips, it seems, and pay no attention to them.

Hi Ann – I’m still getting new questions this morning about it. Linda was the first to ask. Interestingly these type of image artifacts are quite common, they happen every few days. We get inquiries on them ~ once a year or so.

Justin
Content from External Source
 

Rory

Senior Member.
I wonder if it took another one because it detected there was a glitch in the first one?

It seems kind of random what they take and when they take it. I've seen others that were shot at 13 second intervals without any apparent glitching in the photos, and several photos in a short span looks pretty normal.

Also, a lot of the pictures are of nothing much (also from Sol 3613):

Screen Shot 2022-10-26 at 16.46.14.png
Screen Shot 2022-10-26 at 16.50.26.png

If there's any rhyme or reason I'm not seeing it.
 
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Stingray

New Member
If they get inquiries like this every year and this is a textbook cosmic ray, why are their examples so different from the subject picture?
 

deirdre

Senior Member.
I wonder if it took another one because it detected there was a glitch in the first one?
could it be the same pic and they just ran it through the "desmearing" process again? or..it doesn't work that way, the processing stuff?
the pics are literally identical.
 

AmberRobot

Active Member
If they get inquiries like this every year and this is a textbook cosmic ray, why are their examples so different from the subject picture?
Cosmic ray hits can look different from each other depending on the angle of entry and the energy of the particle.
 

AmberRobot

Active Member
I wonder if it took another one because it detected there was a glitch in the first one?
I don’t think “glitch” is the correct word for a cosmic ray hit. “Glitch” implies, at least to me, an improper functioning and that’s not the case when a cosmic ray hits. I also doubt there’s any on-board analysis taking place that would suggest additional photos are taken based on the results of a previous photo. The so-called “flight software” may do a certain level of processing and error checking but I would be surprised if a CR hit would trigger any specific action.
 

AmberRobot

Active Member
could it be the same pic and they just ran it through the "desmearing" process again? or..it doesn't work that way, the processing stuff?
the pics are literally identical.
The “desmearing” process as I read it is to correct for the fact that during the 5ms it takes to transfer the frame from the active area to the covered region some additional charge is collected. This would then correct along columns as that is the direction of the transfer.
 

AmberRobot

Active Member
So not textbook, just an odd looking one that they didn't have examples of? Or can you show me examples?
Attached are the two photos that were sent to me by my JPL contact as examples of cosmic ray hits. One shows up dark -- i.e., hit during the bias frame -- and one that shows up light -- i.e., hit during image frame.

When I have worked on space-based sensors there are a lot more cosmic ray hits and so I've seen a variety of shapes and sizes. When the CR rate is high, multiple exposures tend to be taken and then a total image is assembled by median filter of the exposures. Since CR hits are essentially random the probability of a pixel being impacted in back to back exposures is extremely small, so their impacts can be removed easily with this method.

The first time I saw a raw, unprocessed Hubble image I was shocked!
 

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