Mars lander stays quiet as weather deteriorates

NASA's Phoenix Mars lander has failed to respond to wake-up calls from Earth, a sign that it could be near its end. Mission managers sent pings to Phoenix late Wednesday and early Thursday, but it did not respond to an orbiting spacecraft passing overhead. The six-legged lander went into safe mode this week because of low power. Its power supply has been hampered by declining sunlight with the approaching Martian winter. Engineers will try again to re-establish contact with Phoenix, which has been digging and conducting science experiments in the Martian arctic plains since May.