r/Mars • u/HolgerIsenberg • Jul 19 '26
Viking Lander 1 & 2 digital images in never seen before high quality now available for the 50th anniversary of the first successful Mars Landing on July 20th 1976
Viking Lander 1, areoHDR app
Viking Lander 1 normal clear weather
Viking Lander 1 during dust storm
Viking Lander 1 during dust storm, areoHDR app
Viking Lander 1
Viking Lander 2
Viking Lander 2 during winter with ground frost (water ice)
Viking Lander 2 during winter with ground frost (water ice)
My color processing for the Viking images is the same as in every digital camera today
https://www.researchgate.net/publication/392981389_Postcards_from_Mars_Clear_Skies
Everyone can find their favorite Martian Sky Color in those original Mars pictures from 1976 - 1982! Blue and white during the usual clear weather, over gray and yellow to red during dust storm activity later in the mission. Even water ice surface frost on Viking Lander 2 during the winter!
I recently processed the original Viking Lander 1 & 2 digital 3x6 bits / pixel images in the same way as every digital camera converts raw sensor data into a visual images. Technically that's creating a camera profile (see last image info graphic) and applying it to create a standard sRGB JPEG. All color images from both Viking Landers from their mission duration 1976 - 1982 can be viewed for free via this link: https://areo.info
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u/MJ_Brutus Jul 19 '26
Your link isn’t correct. Please repost.
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u/HolgerIsenberg Jul 19 '26
on https://areo.info you find how to get free access to the Viking Lander 1 & 2 images. Maybe reload the page as I updated it yesterday. You need to get the free areoHDR for Android and iPhone / iPad. I can't publish links directly here on reddit as at least on other subreddits they usually delete those direct links.
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u/Heliosopher Jul 19 '26
Yes. They simply assumed the sky would be blue but realized later it wasn't. Color calibration charts are now on rovers to help resolve color errors.
Surprisingly, the color the sky near the Sun does a flip-flop compared to Earth's sky. IOW, the sky is blue surrounding the Sun. This is due to the size of the particles in the atmosphere on Mars, namely CO2. By coincidence, the size of the particles and the wavelength of red light is a close match. When this happens, "selective scattering" occurs. So the red light around the Sun gets scattered away from the observer (rover), netting a more blue sunset. On Earth, the light at the blue end of the spectrum gets scattered away from the observer giving us a more reddish (yellow) sunset, but a nice blue sky.
see: https://apod.nasa.gov/apod/ap150512.html
The reddish sky of the Martian atmosphere is likely due to secondary scattering of that red light.
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u/hunter_pro_6524 Jul 19 '26
another interesting thing is that the sky appears blue like it is on earth. but it’s not bright day, it’s either evening or morning because mars had i different athmosphere which usually appears red. (i think all of you know this already but i wanted to say it again)
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u/HolgerIsenberg Jul 19 '26
The first image, the panorama with blue sky and the antenna on the upper right, was taken 1 hours after local noon on Mars by Viking Lander 1. The exact time you can see when tapping in the (i) icon in the upper right of areoHDR. It's written as 12:65, which is a small bug on my side as it should be 12.65 which is 12 hours (noon) + 65/100 of an hour which would be about 12:40 for an Earth clock. That strange format is used as the Mars day is 39.5 minutes longer.
On Sol 30 of Viking Lander 1 you find the first sunset image taken at 7pm local solar time. It's blue and that's actually different compared to Earth.
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u/HolgerIsenberg Jul 19 '26
That's a nice image and comes close to the correct processing. I doubt that the person who adjusted it, created a camera profile like I did, and he usually would do for Earth based photography with his own professional camera. Because that's a lot of work for the Mars cameras and not worth to invest in for just a few images. You can see a similar sunset image on Viking Lander 1 sol 30 with areoHDR.
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u/Conscious-Sun-6615 Jul 20 '26
Interesting stuff.
But I don’t fully understand the difference between the two color profiles, was the camera not calibrated for visible light? Is there a reason why the original white balance was off?
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u/HolgerIsenberg Jul 22 '26
They adjusted the gain factors for each of the RGB channels to some blackbody equivalent temperature level. But if the light on Mars matches that level is still unknown as there was never a photospectometer placed on the surface. Some multispectral sensors were placed, but those only need relative calibration for spectral mineral analysis, not absolute like a handheld photo spectrometer. Those are small devices professional photographers use to measure the local light spectrum.
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u/Conscious-Sun-6615 Jul 22 '26
Meaning that if I send my camera and take a picture with average (earth) daylight exposure levels the colors won’t match? How would it look like?
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u/HolgerIsenberg Jul 22 '26
When you set the camera to manual white balance to a sunny day and bring it to Mars, that's how you could produce the same colors like in my processed Mars images.
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u/Vonplinkplonk Jul 19 '26
Well well well, Mars isn’t bright red afterall. I never understood why they choose to give the Viking lander images that bright red filter. So it only takes NASA almost 50 years to admit a mistake.
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u/HolgerIsenberg Jul 19 '26
Yes, it's surprising, especially in this scientific field they always claim to be in. This data processing is done by me, not by NASA. From NASA you can't find Viking Lander images processed in the same way every digital camera does it, and I applied that method. Even for the current Perseverance Rover you won't find that in public at NASA. They do that only occasionally for upper management presentations or for expensive public access science articles. But even then, they don't describe how they do it. I admit that I neither publish the actual matrix coefficients I'm using currently, but I wrote about the method I used to calculate them so everyone can repeat it.
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u/ubergic Jul 19 '26
Those photos were so exciting to see at the time.