A study of meteorites chipped off the surface of Mars suggests the planet has been frozen for 4 billion years and probably never had the warm wet conditions that could have given rise to life, two researchers said on Thursday. Their study of two meteorites that fell to Earth suggests they were never in warm conditions. The report, published in the journal Science, contradicts theories the now-frozen planet may once have been warm enough for life to have arisen. "First, we evaluated what the meteorites could have experienced during ejection from Mars, 11 to 15 million years ago, in order to set an upper limit on the temperatures in a worst-case scenario for shock-heating,' said Benjamin Weiss, an assistant professor at the Massachusetts Institute of Technology.