Strange Martian
Lines Explained
Jay Michael Long, who originally submitted the interesting "lines" image from Viking surface photos, contacted NASA for an explaination:

Dear sir,

At the above URL there is a photo depicting the landing site of the Pathfinder, toward the bottom and to the left of the "Really Far Knob" there are a series of very straight "Lines" cut into the surface of Mars that appear to me to be to straight to be naturally occuring. I am interested in your explanation of these "lines." As a reference I have attached a cropped photo of the area in question for your study. I am very interested in your/Nasa's opinion of these lines. Could you take a look at the photo and reply as soon as possible?

Thank you,

J. Michael Long
You are right. The lines are not natural. However, they aren't on Mars either. The Viking Orbiter images often contain bands of these lines near one edge that were caused by electronic interference by other spacecraft components while the images were being taken. Since they are highly variable, depending on the noise conditions while the specific image was taken, it is not easy to filter them out of the final product. What I usually will do when assembling a mosaic of Viking images is cut out the areas where these noise bands occur if there is another high resolution image of the area that is free of the noise. In areas where there isn't other high resolution coverage, I will leave the noise in rather than rely on the low resolution background image. Such was the case when assembling this mosaic. Notice the area at the right edge of the image on the web page is blurrier than the rest of the scene. This is the next highest resolution coverage that is available. You'll notice that the noise is less objectionable than the low resolution data.
Tim Parker

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