There is a known reason for this (among radiation belt enthusiasts) that the authors either don't mention or don't know. Hubble's orbit is in the inner Van Allen belt, where the radiation intensity is out of phase with the solar cycle (because the atmosphere is thinner at solar minimum, and expands at solar maximum, affecting the inner radiation belt). See Figure 6 (https://agupubs.onlinelibrary.wiley.com/cms/asset/718954d6-3...) of this paper (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JA02...). Hubble is in a low altitude, near equatorial orbit, so the red curve (small L) is the most relevant one.
Is the relevant radiation solar radiation, or is there damage from radiation coming from the direction the optics are pointed? If it's the latter, then maybe the sun's emissions interact with inbound particles from sources outside the solar system? (I don't have sufficient background or time to check whether the paper already rules this out.)
Seeing visible light flashes in the scintillator was one of oldest ways how we observed ionizing radiation. It's more then 100 years old method.
"This built upon the work of earlier researchers such as Antoine Henri Becquerel, who discovered radioactivity whilst working on the phosphorescence of uranium salts in 1896. Previously, scintillation events had to be laboriously detected by eye, using a spinthariscope (a simple microscope) to observe light flashes in the scintillator."
Can anyone tell whether these exposures occurred through the camera lens (from fallout particles in the sky of the depicted scenes) or in post- (or pre-) exposure handling of the film from hot dust carried by the photographer?
There's no reason they would preferentially travel through the lens and hit the current frame because most of the camera and film housing is about as transparent to gamma radiation as glass. Or maybe more transparent, because glass lenses in pro cameras tend to be rather bulky.
So this just happened somewhere between arrival to and departure from the zone.
They are not part of the image of the scene. They wouldn't be focused by the optics.
The optics would just be a slight attenuation much like the rest of the camera housing, film reel, operator, etc. So really a summation of all the exposure types you can imagine.
I suppose I got lucky with the search terms on YouTube, I remember watching a documentary showing the first sight of the reactor filmed from a helicopter, and the narrator saying "The flashes of light on the footage are due to radiation". I was hoping to find this heli video on YouTube, but all the "chernobyl heli" footage are from the TV series, or very very low res. The video above isn't what I was looking for, but it shows the effects of radiation very well.
Sheesh, but DuckDuckGo and Google are quite useless. I just tried to see if The Internet has a record of the heli that flew to Chernobyl to shoot that first footage of the blown reactor (IIRC from Moscow, although that does not seems a plausible flying distance), and the search engines think I want to instead find out about the heli that crashed after hitting a crane...
They take two pictures, each taking up half the total observation period. If you subtract the two images, the deltas should be the cosmic ray flashes. You can then subtract those out. They use two pictures as opposed to more to minimize the impact of readout noise.
To deal with "stuck pixel" type errors, they can slightly shift the camera between the two observations. They can counter act the shift before doing the initial subtraction.
Signal processing / denoising of astronomical images is a field of study onto itself.
If you are like me you will find it super interesting. There is immense variety based upon what kind of telescope, what do you want to capture, whether it's for science or astrophotography (aesthetics).
If you are into math side of things you can begin with Richardson-Lucy as a starting point and stacking.
its actually quite doable. any cosmic rays will not be present in two pictures in a row. any permanent damage will be exactly the same in all pictures.
It's well known that higher solar wind/CMEs density/speed/etc that comes with the peak of the 11 year intensity cycles scatters cosmic rays before they enter the inner heliosphere. Combine this with the 1~3 years it takes for the solar wind to travel out through the heliosphere and you get the phase difference. Really cool unintended sensor empirical data on it though.
Don't try to correlate with the sun spots, correlate with the solar wind/cmes from the spots getting out far enough to effectively scatter the incoming cosmic rays away.
Coronal mass traveling at a higher speed "sweeps" what's before it. You can see the spiral shape, and you can probably figure out that the stuff is slowing down as it moves outward.
Watch this occasionally for a few months and you'll get the idea, although solar activity is slowing down somewhat (as expected).
If you carefully re-read what GP wrote, you'll see there's no reference to Earth's orbit or 1 AU in there. GP wrote about the solar wind scattering cosmic rays when it reached some point in its outward travel.
The paper claims directly "the rate of degradation over time remains unsatisfactorily unpredictable" but you are claiming the authors do not understand or are unaware of the point you are making?
I think what I explained is known by anyone in solar physics. I cannot believe they would not have discussed it. It's absence in the paper is weird. But I think unpredictable refers more to LEO in the context of the paper where things are indeed more dynamic that just the 11 year periodicity of cosmic rays from solar activity causing scattering in the heliosphere.
There is a known reason for this (among radiation belt enthusiasts) that the authors either don't mention or don't know. Hubble's orbit is in the inner Van Allen belt, where the radiation intensity is out of phase with the solar cycle (because the atmosphere is thinner at solar minimum, and expands at solar maximum, affecting the inner radiation belt). See Figure 6 (https://agupubs.onlinelibrary.wiley.com/cms/asset/718954d6-3...) of this paper (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JA02...). Hubble is in a low altitude, near equatorial orbit, so the red curve (small L) is the most relevant one.
Is the relevant radiation solar radiation, or is there damage from radiation coming from the direction the optics are pointed? If it's the latter, then maybe the sun's emissions interact with inbound particles from sources outside the solar system? (I don't have sufficient background or time to check whether the paper already rules this out.)
you should see what cosmic rays do to space telescopes
public almost never sees what raw images look like
RAW https://blog.galaxyzoo.org/wp-content/uploads/2010/04/spiral...
FINAL https://blog.galaxyzoo.org/wp-content/uploads/2010/04/spiral...
* https://blog.galaxyzoo.org/2010/04/12/how-to-handle-hubble-i...
they also slowly destroy the sensors since they are physical particles moving at almost the speed of light
Reminds me of the radiation after Chernobyl causing flashes on the physical film: https://www.youtube.com/watch?v=KOLBEx5DBaE
Seeing visible light flashes in the scintillator was one of oldest ways how we observed ionizing radiation. It's more then 100 years old method.
"This built upon the work of earlier researchers such as Antoine Henri Becquerel, who discovered radioactivity whilst working on the phosphorescence of uranium salts in 1896. Previously, scintillation events had to be laboriously detected by eye, using a spinthariscope (a simple microscope) to observe light flashes in the scintillator."
https://en.wikipedia.org/wiki/Scintillation_counter
Can anyone tell whether these exposures occurred through the camera lens (from fallout particles in the sky of the depicted scenes) or in post- (or pre-) exposure handling of the film from hot dust carried by the photographer?
There's no reason they would preferentially travel through the lens and hit the current frame because most of the camera and film housing is about as transparent to gamma radiation as glass. Or maybe more transparent, because glass lenses in pro cameras tend to be rather bulky.
So this just happened somewhere between arrival to and departure from the zone.
They are not part of the image of the scene. They wouldn't be focused by the optics.
The optics would just be a slight attenuation much like the rest of the camera housing, film reel, operator, etc. So really a summation of all the exposure types you can imagine.
thank you so much for this link! I have been trying to search for footage of this phenomenon (in the pre-llm era) 10+y ago
I suppose I got lucky with the search terms on YouTube, I remember watching a documentary showing the first sight of the reactor filmed from a helicopter, and the narrator saying "The flashes of light on the footage are due to radiation". I was hoping to find this heli video on YouTube, but all the "chernobyl heli" footage are from the TV series, or very very low res. The video above isn't what I was looking for, but it shows the effects of radiation very well.
Sheesh, but DuckDuckGo and Google are quite useless. I just tried to see if The Internet has a record of the heli that flew to Chernobyl to shoot that first footage of the blown reactor (IIRC from Moscow, although that does not seems a plausible flying distance), and the search engines think I want to instead find out about the heli that crashed after hitting a crane...
The corona monitoring satellite cameras "blink" on incoming xray flares.
Also the sobering footage taken by this YouTuber by sending a GoPro through a particle accelerator: https://www.youtube.com/watch?v=Uf4Ux4SlyT4
The video is not exactly comfortable to watch, but the sound is truly scary.
ahh I love that! YouTube compression not doing it justice
Oh wow, I thought those were stars at first.
thanks for the links, that's really interesting to look at
do you happen to know how exactly those artifacts are cleaned up?
The blog link describes the cleanup process.
They take two pictures, each taking up half the total observation period. If you subtract the two images, the deltas should be the cosmic ray flashes. You can then subtract those out. They use two pictures as opposed to more to minimize the impact of readout noise.
To deal with "stuck pixel" type errors, they can slightly shift the camera between the two observations. They can counter act the shift before doing the initial subtraction.
Signal processing / denoising of astronomical images is a field of study onto itself.
If you are like me you will find it super interesting. There is immense variety based upon what kind of telescope, what do you want to capture, whether it's for science or astrophotography (aesthetics).
If you are into math side of things you can begin with Richardson-Lucy as a starting point and stacking.
funny how this also eliminates "close" fast moving objects. which I guess is a feature for a telescope
I mean funny in the sense of "we did not find any anomalies, because we are careful to filter them out"
One way is to take a “blank” picture which will then show just the noise; then use that as a reference for what can be removed from the image.
The blank should only show long term damage. Hits while the sensor is collecting light can be averaged out from multiple readings of the sensor.
its actually quite doable. any cosmic rays will not be present in two pictures in a row. any permanent damage will be exactly the same in all pictures.
photoshop ;D, or using multiple pictures
This sounds like the "hmm this is strange" first step of discovery.
cue:ominous creapy alien sound track .play
And the nearest star to our solar system is 4.3 light years away. Coincidence?
:-)
careful, the Alpha Centaurians might be on HN ...
It's well known that higher solar wind/CMEs density/speed/etc that comes with the peak of the 11 year intensity cycles scatters cosmic rays before they enter the inner heliosphere. Combine this with the 1~3 years it takes for the solar wind to travel out through the heliosphere and you get the phase difference. Really cool unintended sensor empirical data on it though.
Don't try to correlate with the sun spots, correlate with the solar wind/cmes from the spots getting out far enough to effectively scatter the incoming cosmic rays away.
I thought it only takes a few days for solar wind to travel from the sun to the Earth? Can you clarify?
Coronal mass traveling at a higher speed "sweeps" what's before it. You can see the spiral shape, and you can probably figure out that the stuff is slowing down as it moves outward.
Watch this occasionally for a few months and you'll get the idea, although solar activity is slowing down somewhat (as expected).
https://www.spaceweather.gov/products/wsa-enlil-solar-wind-p...
If you carefully re-read what GP wrote, you'll see there's no reference to Earth's orbit or 1 AU in there. GP wrote about the solar wind scattering cosmic rays when it reached some point in its outward travel.
The paper claims directly "the rate of degradation over time remains unsatisfactorily unpredictable" but you are claiming the authors do not understand or are unaware of the point you are making?
I think what I explained is known by anyone in solar physics. I cannot believe they would not have discussed it. It's absence in the paper is weird. But I think unpredictable refers more to LEO in the context of the paper where things are indeed more dynamic that just the 11 year periodicity of cosmic rays from solar activity causing scattering in the heliosphere.
Identifying a mechanism is not predicting its rate.
There may be another variable they’re trying to pin down.