An asteroid may come uncomfortably close to Earth in 2036 and the United Nations should assume responsibility for a space mission to deflect it, a group of astronauts, engineers and scientists said on Saturday. Astronomers are monitoring an asteroid named Apophis, which has a 1 in 45,000 chance of striking Earth on April 13, 2036. Although the odds of an impact by this particular asteroid are low, a recent congressional mandate for NASA to upgrade its tracking of near-Earth asteroids is expected to uncover hundreds, if not thousands of threatening space rocks in the near future, former astronaut Rusty Schweickart...