Nasa's asteroid-hunting spacecraft set to blast off TONIGHT

Later today Nasa hopes to launch a spacecraft on its journey towards an asteroid, where it will collect and return samples that experts believe may hold the building blocks of life. Nasa's OSRIS-REx spacecraft will travel for two years to reach Bennu, and plans to return to Earth in 2023. Fitted with sensors, the craft will map out the surface of the asteroid in order to address basic questions about the composition of the very early solar system. Final preparations: Forecasters said good weather was expected for the 7:05 PM EDT launch. But Nasa has until mid-October to send the SUV-size spacecraft on its way.