NASA 's Curiosity Mars rover has identified seven organic compounds in rock near the planet's equator, five of which had not previously been found on Mars.  Researchers publishing in the journal Nature Communications on Tuesday said the experiment also hinted at the presence of another organic compound bearing a structure similar to the precursors to DNA, the molecule that carries genetic information in living organisms on our planet.  However the scientists also noted that the organic compounds — molecules primarily composed of carbon atoms bonded to other elements that form the structural basis of all life on Earth — could have formed through nonbiological processes. Further evidence that Mars may have been a habitable planet billions of years ago Like the Earth and other planets in the solar system, Mars is thought to have formed around 4.5 billion years ago.…