What was thought to be the signs of water on Mars has turned out to be an illusion, or mostly so? Upon closer examination, NASA scientists realize that most of the images taken by the Mars Reconnaissance Orbiter were showing things that were not really there. This resulted from a technical error developed by the Mars orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). The task of CRISM was to identify moisture-absorbing minerals on the surface of the planet by measuring waves of visible and invisible light corresponding to chemical structures. These were later mapped into pixels to represent an area of about 330 to 660 feet wide. Marking such areas where water-absorbent chemicals are present would later help in identifying the distribution of water across the planet.
The images made by CRISM contained many pixels showing the presence of minerals like kieserite, serpentine alunite and perchlorate. This made scientists very optimistic about finding the presence of water on the planet. However, upon closer examination, it turned out that the pixels were created by data spikes caused when CRISM’s detector moved among fields of bright light and shady areas. In other words, the pixels represented minerals that were not actually there on the surface of the planet. This came in as a big disappointment for the scientists who initially thought that the images showed an abundance of water-absorbent minerals over there.
However, the disappointment is not total. The scientists developed a method to filter out the spikey noise and managed to develop a better resolution of the image. The result suggests that perchlorate deposits are indeed present on the planet, though at a much lesser level than initially thought. It was found that 0.05 percent of the pixels represent perchlorate deposits for real. With the atmosphere of Mars too cold and thin it is not possible that water exists on the surface in liquid form. Yet, the presence of the salts indicates a thin possibility of the presence of water on the planet. It doesn’t amount to much, but it is a starting point for further investigations.