The search for signs of life on Mars continues to yield promising data. A first-of-its-kind wet chemistry experiment, published Tuesday in Nature , confirmed the presence of essential ingredients of life preserved in ancient Martian sandstones. The molecules were found inside 3.5-billion-year-old sandstone. NASA's Curiosity rover collected the clay-filled rocks from an area called Glen Torridon, inside Mars' enormous Gale Crater. The rover's Sample Analysis at Mars (SAM) mobile instrument suite analyzed the data. The experiment was unique as the first off-Earth study to use the chemical tetramethylammonium hydroxide (TMAH). The reagent allows Curiosity to break down larger organic molecules on the Martian surface, reducing them to something the rover's instruments can read. It revealed the presence of over 20 different organic molecules. Among the data was confirmation of naphthalene and benzothiophene, some of the largest and most complex organic compounds discovered on the Red Planet.…