<p>There is a sequence of <strong>three</strong> raw images by Mars Curiosity Rover taken during Sol 3066 (22/03/2022, roughly) that show the same features of Mars' landscape and sky. They are separated by 38 seconds' difference each. <a href="https://mars.nasa.gov/raw_images/912749/" rel="nofollow noreferrer">This</a> is the first one. <a href="https://mars.nasa.gov/raw_images/912751/" rel="nofollow noreferrer">This</a> is the last one. Interestingly, the <strong><a href="https://mars.nasa.gov/raw_images/912750/" rel="nofollow noreferrer">middle one</a></strong> shows a black, oval spot in the low sky, that is not present in the other two:</p>
<p><a href="https://i.sstatic.net/eDfeI.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/eDfeI.jpg" alt="https://mars.nasa.gov/raw_images/912750/" /></a></p>
<p>Just in case some one think I have some obscure intentions, I state I am not an UFO fan, conspiracy theory fan, or anything like that. This is a genuine question.</p>
<p>So, what do you think that might be? Could well be camera noise, or perhaps a satellite (there are a few orbiting Mars), or just some storm debris (there are quite a lot of storms in Mars). Any guesses?</p>
<hr />
<p>Here's a section blown up so that every pixel produced by the JPGEG is now 5x5 pixels simply to make it easier to see the artifact:</p>
<p><a href="https://i.sstatic.net/Uh87O.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Uh87O.png" alt="manipulated from https://mars.nasa.gov/raw_images/912750/" /></a></p>
<hr />
<p>Update: Ok, it seems there are lots of similar images. For instance, an image from more recent Sol (3067) also <a href="https://mars.nasa.gov/msl-raw-images/msss/03067/mcam/3067MR0160210001400044C00_DXXX.jpg" rel="nofollow noreferrer">shows</a> a black spot in the sky. An image a bit earlier <a href="https://mars.nasa.gov/raw_images/912748/?site=msl" rel="nofollow noreferrer">shows</a> a white spot (from comment below). <a href="https://mars.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/03014/opgs/edr/ncam/NRB_665058178EDR_F0851808NCAM00560M_.JPG" rel="nofollow noreferrer">Here</a> there is what it looks like a meteorite with a trail.</p>

CC BY-SA 4.0
2021-03-23T01:51:02.990Z
This is on-topic here but just to let you know that questions about images taken by spacecraft cameras on other planets are also answered in [Space Exploration SE](https://space.stackexchange.com/). CCDs have all kinds of artifacts but usually they are bright. Tracks from cosmic rays are common. But this dark feature is not so easy to dismiss.
uhoh
CC BY-SA 4.0
2021-03-23T02:05:01.480Z
@uhoh Oh, thanks. Didn't know that site exist! That site might be more appropriate for it, don't know. I imagine mods can make a decision whether to move or keep it. I have no prior. (and thanks for the image close-up, very good idea).
luchonacho
CC BY-SA 4.0
2021-03-23T02:55:10.587Z
Dust on the lens?  I don't think it's dead pixels, unless there's been some compression in order to make the edge fuzzy.
Stuart Robbins
CC BY-SA 4.0
2021-03-23T09:58:17.280Z
@StuartRobbins dust on the lens would be out of focus; this is of order 1 pixel wide. It has to be something either fairly distant and within the DOF of the lens, or happening very near or in the CCD.
uhoh
CC BY-SA 4.0
2021-03-23T10:01:56.910Z
@luchonacho the standard process is for the question to be first closed by community members as off-topic, then a request is made (via flag) for migration. For this one I think you could consider flagging even before closing. But now that it's here maybe wait a few days to see if an answer appears?
uhoh
CC BY-SA 4.0
2021-03-23T12:35:30.853Z
could it be Phobos or Dimos at near new moon? The image seems to be looking (nearly) into sunward direction (just left of image). But if the answer should be yes... I will be surprised about the amount of light reduction... Possibly more likely the influence of cosmic radiation on the read-out electronics (which reads-out a number of pixels at once) or in the transmission (though I recon that's unlikely as some error-correcting form will be chosen)
planetmaker
CC BY-SA 4.0
2021-03-23T18:50:50.403Z
Are those the original images? There are many possibilities for errors to appear in a digital image being transmitted from Mars. An error can be introduced anywhere between the camera and the screen of the viewer. There's a lot of technology that can be researched between those two locations.
L d Bonnie
CC BY-SA 4.0
2021-03-23T23:19:31.043Z
There's also a mystery white spot in an [image taken 76 seconds earlier](https://mars.nasa.gov/raw_images/912748/?site=msl).
Alex Hajnal
CC BY-SA 4.0
2021-03-24T02:30:57.500Z
@LdBonnie NASA JPL has known about error correction for over a half-century. The image data is under JPL control all the way from designing the camera and computer of the spacecraft to receiving the data on earth to processing and publishing the image.
uhoh
CC BY-SA 4.0
2021-03-24T23:50:56.740Z
@AlexHajnal And another black spot in a [newer image](https://mars.nasa.gov/msl-raw-images/msss/03067/mcam/3067MR0160210001400044C00_DXXX.jpg).
luchonacho
CC BY-SA 4.0
2021-03-25T00:08:17.613Z
@luchonacho Must be aliens.
Alex Hajnal
CC BY-SA 4.0
2021-03-25T01:16:28.707Z
@AlexHajnal And a [meteorite with a trail](https://mars.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/03014/opgs/edr/ncam/NRB_665058178EDR_F0851808NCAM00560M_.JPG)?
luchonacho
CC BY-SA 4.0
2021-03-25T02:28:45.070Z
@planetmaker how can a moon *outside the atmosphere* make the sky in front of it darker? That doesn't make sense, The sky brightness is additive, that's why the shadowed part of the moon during the day is sky blue rather than dark. [1](https://commons.wikimedia.org/wiki/File:Playing_a_tune_for_the_Moon.jpg), [2](https://commons.wikimedia.org/wiki/File:Daytime_moon_december_2017.jpg), [3](https://commons.wikimedia.org/wiki/File:Daytime_moon_(4055277162).jpg), [4](https://en.wikipedia.org/wiki/File:Trifecta_Morning_Mountain_Moonset_01-31-2018.jpg)...
uhoh
CC BY-SA 4.0
2021-03-25T02:30:51.510Z
...[5](https://commons.wikimedia.org/wiki/File:Daytime_Moon_Over_Monument_8.2.jpg) this one is nice!
uhoh
CC BY-SA 4.0
2021-03-25T03:44:56.230Z
[Anyone remember this?](https://atomfullerene.wordpress.com/dispatches-from-the-red-planet/)
Alex Hajnal
<photography><mars><identify-this-object>
Black spot in Mars' sky
luchonacho
# Black spot in Mars' sky

(Asked by: username_0 on 2021-03-22)

There is a sequence of **three** raw images by Mars Curiosity Rover taken during Sol 3066 (22/03/2022, roughly) that show the same features of Mars' landscape and sky. They are separated by 38 seconds' difference each. [This](https://mars.nasa.gov/raw_images/912749/) is the first one. [This](https://mars.nasa.gov/raw_images/912751/) is the last one. Interestingly, the **[middle one](https://mars.nasa.gov/raw_images/912750/)** shows a black, oval spot in the low sky, that is not present in the other two:

[![https://mars.nasa.gov/raw_images/912750/](https://i.sstatic.net/eDfeI.jpg)](https://i.sstatic.net/eDfeI.jpg)

Just in case some one think I have some obscure intentions, I state I am not an UFO fan, conspiracy theory fan, or anything like that. This is a genuine question.

So, what do you think that might be? Could well be camera noise, or perhaps a satellite (there are a few orbiting Mars), or just some storm debris (there are quite a lot of storms in Mars). Any guesses?

---

Here's a section blown up so that every pixel produced by the JPGEG is now 5x5 pixels simply to make it easier to see the artifact:

[![manipulated from https://mars.nasa.gov/raw_images/912750/](https://i.sstatic.net/Uh87O.png)](https://i.sstatic.net/Uh87O.png)

---

Update: Ok, it seems there are lots of similar images. For instance, an image from more recent Sol (3067) also [shows](https://mars.nasa.gov/msl-raw-images/msss/03067/mcam/3067MR0160210001400044C00_DXXX.jpg) a black spot in the sky. An image a bit earlier [shows](https://mars.nasa.gov/raw_images/912748/?site=msl) a white spot (from comment below). [Here](https://mars.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/03014/opgs/edr/ncam/NRB_665058178EDR_F0851808NCAM00560M_.JPG) there is what it looks like a meteorite with a trail.

**Tags:** photography, mars, identify-this-object
> **Comments:**
> **username_1**: This is on-topic here but just to let you know that questions about images taken by spacecraft cameras on other planets are also answered in [Space Exploration SE](https://space.stackexchange.com/). CCDs have all kinds of artifacts but usually they are bright. Tracks from cosmic rays are common. But this dark feature is not so easy to dismiss.  
> **username_0**: @uhoh Oh, thanks. Didn't know that site exist! That site might be more appropriate for it, don't know. I imagine mods can make a decision whether to move or keep it. I have no prior. (and thanks for the image close-up, very good idea).  
> **username_2**: Dust on the lens?  I don't think it's dead pixels, unless there's been some compression in order to make the edge fuzzy.  
> **username_1**: @StuartRobbins dust on the lens would be out of focus; this is of order 1 pixel wide. It has to be something either fairly distant and within the DOF of the lens, or happening very near or in the CCD.  
> **username_1**: @luchonacho the standard process is for the question to be first closed by community members as off-topic, then a request is made (via flag) for migration. For this one I think you could consider flagging even before closing. But now that it's here maybe wait a few days to see if an answer appears?  
> **username_3**: could it be Phobos or Dimos at near new moon? The image seems to be looking (nearly) into sunward direction (just left of image). But if the answer should be yes... I will be surprised about the amount of light reduction... Possibly more likely the influence of cosmic radiation on the read-out electronics (which reads-out a number of pixels at once) or in the transmission (though I recon that's unlikely as some error-correcting form will be chosen)  
> **username_4**: Are those the original images? There are many possibilities for errors to appear in a digital image being transmitted from Mars. An error can be introduced anywhere between the camera and the screen of the viewer. There's a lot of technology that can be researched between those two locations.  
> **username_5**: There's also a mystery white spot in an [image taken 76 seconds earlier](https://mars.nasa.gov/raw_images/912748/?site=msl).  
> **username_1**: @LdBonnie NASA JPL has known about error correction for over a half-century. The image data is under JPL control all the way from designing the camera and computer of the spacecraft to receiving the data on earth to processing and publishing the image.  
> **username_0**: @AlexHajnal And another black spot in a [newer image](https://mars.nasa.gov/msl-raw-images/msss/03067/mcam/3067MR0160210001400044C00_DXXX.jpg).  
> **username_5**: @luchonacho Must be aliens.  
> **username_0**: @AlexHajnal And a [meteorite with a trail](https://mars.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/03014/opgs/edr/ncam/NRB_665058178EDR_F0851808NCAM00560M_.JPG)?  
> **username_1**: @planetmaker how can a moon *outside the atmosphere* make the sky in front of it darker? That doesn't make sense, The sky brightness is additive, that's why the shadowed part of the moon during the day is sky blue rather than dark. [1](https://commons.wikimedia.org/wiki/File:Playing_a_tune_for_the_Moon.jpg), [2](https://commons.wikimedia.org/wiki/File:Daytime_moon_december_2017.jpg), [3](https://commons.wikimedia.org/wiki/File:Daytime_moon_(4055277162).jpg), [4](https://en.wikipedia.org/wiki/File:Trifecta_Morning_Mountain_Moonset_01-31-2018.jpg)...  
> **username_1**: ...[5](https://commons.wikimedia.org/wiki/File:Daytime_Moon_Over_Monument_8.2.jpg) this one is nice!  
> **username_5**: [Anyone remember this?](https://atomfullerene.wordpress.com/dispatches-from-the-red-planet/)  

---

## 0 answers

