'Crowd-funded' telescope to keep sky watch

A former NASA astronaut says he is launching a crowd-funded program to build an orbiting space telescope for spotting asteroids that may threaten Earth. The telescope, dubbed Sentinel, would launch in 2017 or 2018, drift toward Venus and then spend more than 5 years surveying the inner solar system while orbiting the sun, said Ed Lu, a physicist who flew on the space shuttle and the international space station. Asteroids larger than about 100 feet across -- large enough to threaten cataclysm should they hit Earth -- will be visible to the space telescope's eye, he said. Observations by Sentinel are meant to provide time to prepare a mission to deflect or destroy threatening asteroids, The Washington Post reported Thursday. Lu acknowledges the project needs to raise "a few hundred million" dollars to get off the ground. "This is crowdsourcing but on a grand level," he said. NASA spends millions annually searching for giant "planet killer" asteroids but no one is looking for smaller but still possibly dangerous space rocks, Lu said. "The chances were pretty minimal somebody else was going to do this," Lu said. "Federal budgets being what they are, it's just not going to happen" without public participation, he said.