File:Mars Viking 21i093.png

Summary

DescriptionMars Viking 21i093.png	English: This false color photo of the surface of Mars was taken by Viking Lander 2 at its Utopia Planitia landing site on May 18, 1979, and relayed to Earth by Orbiter 1 on June 7. It shows a thin coating of water ice on the rocks and soil. The time the frost appeared corresponds almost exactly with the buildup of frost one Martian year (23 Earth months) ago. Then it remained on the surface for about 100 days. Scientists believe dust particles in the atmosphere pick up bits of solid water. That combination is not heavy enough to settle to the ground. But carbon dioxide, which makes up 95 percent of the Martian atmosphere, freezes and adheres to the particles and they become heavy enough to sink. Warmed by the Sun, the surface evaporates the carbon dioxide and returns it to the atmosphere, leaving behind the water and dust. The ice seen in this picture, like that which formed one Martian year ago, is extremely thin, perhaps no more than one-thousandth of an centimeter thick. The view is looking towards the south southeast, the long boulder to the right is roughly one meter across.
Date	2010-02-25; original photo was taken 1979-05-18.
Source	Own work based on images in the NASA Viking image archive See accurate colors at: PIA00571: Ice on Mars Utopia Planitia Again العربية: صورةٌ لسطح كوكبِ المريخ مُلتقَطة في التاسع من كانون الأول/ديسمبر عام 1977
Author	"Roel van der Hoorn (Van der Hoorn)"
Permission (Reusing this file)	I used the original 21i093.blu, 21i093.grn and 21i093.red images from the NASA Viking image archive, converted them to .png, manually removed the noise and finally merged them into one image (almost matching true color; see here for the channel mixing process). Except for the conversion, this was all done in Adobe Photoshop CS2 and Adobe Photoshop CS4. The original files by NASA are in the public domain, and so is this new one.
Other versions	I created this image as a replacement for File:Ice on Mars Utopia Planitia (PIA00571).jpg and File:Viking2 frost enhance.jpg. These files were created by NASA, but the quality is not very high. Using the original pictures from the Lander archive resulted in a higher quality image.

Licensing

This work has been released into the public domain by its author, Van der Hoorn at English Wikipedia. This applies worldwide.
In some countries this may not be legally possible; if so:
Van der Hoorn grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

The image is based on an original image from NASA to which the following copyright statement is applicable:

	This file is in the public domain in the United States because it was solely created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See Template:PD-USGov, NASA copyright policy page or JPL Image Use Policy.)
	Warnings: Use of NASA logos, insignia and emblems is restricted per U.S. law 14 CFR 1221. The NASA website hosts a large number of images from the Soviet/Russian space agency, and other non-American space agencies. These are not necessarily in the public domain. Materials based on Hubble Space Telescope data may be copyrighted if they are not explicitly produced by the STScI.[1] See also {{PD-Hubble}} and {{Cc-Hubble}}. The SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use. [2] Images featured on the Astronomy Picture of the Day (APOD) web site may be copyrighted. [3] The National Space Science Data Center (NSSDC) site has been known to host copyrighted content. Its photo gallery FAQ states that all of the images in the photo gallery are in the public domain "Unless otherwise noted."

File:Mars Viking 21i093.png

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