Chlorine found on Mars!
NASA’s Curiosity Rover, currently exploring the surface of Mars, has detected the presence of chlorine on the Red Planet.
UPDATE September 2015 - Scientists at NASA, using the Mars Orbiter, have found stripes of hydrated perchlorate minerals on the slopes of Garni crater on Mars. These minerals would help to keep brine (chlorine containing 'water') liquid over a wider range of temperatures and has exciting implications for the search for life on the red planet! These stripes also suggest that the water is flowing at times and could be important for future manned missions!
The Mars Rover Program
One of Rover's major tasks is to analyse the chemical composition of the Martian soil and there have been some interesting results. While the soil largely consists of aluminium, magnesium and calcium oxides, Curiosity has also detected perchlorate.
Perchlorates (sodium-, potassium-, ammonium- etc.) are both naturally occurring and man-made chemicals in which chlorine has its highest valence of +VII. They are commonly used to produce rocket fuel, fireworks, flares and explosives. Sodiumperchlorate for instance, is an inorganic compound with the formula NaClO4. It is the most soluble of the common perchlorate salts. It is a white crystalline, hygroscopic solid that is highly soluble in water and in alcohol. In medicine, perchlorates have been used for more than half a century to treat thyroid disorders. A Mars expert at the University of Michigan in Ann Arbor, US, stated that "the presence of perchlorates implies a source of chlorine, which was most likely derived from briny water or volcanic activity in the past".
NASA also detected chlorinated methane compounds when soil samples were analysed in Curiosity's on-board laboratory. The presence of methane on Mars could be an indicator that life once existed on the Red Planet as it occurs naturally when organic matter decomposes. But, while NASA is certain that the chlorine came from Mars, there is a possibility that the methane compounds were formed when the perchlorates reacted with carbon carried from Earth in Curiosity's laboratory.