If the aliens are coming you might fine out first via your iPod.

NASA is to start broadcasting news via the medium of the podcast.

The new free service is called NASAcast. It allows subscribers to download NASA features, news and other content as part of a new free podcast service.

Content this week will include "This [email protected]" from NASA TV; interviews with Stardust and Mars Exploration Rover scientists; and an interview and concert clips from former Beatle Sir Paul McCartney's historic live hook-up to the International Space Station.

NASA assistant administrator for Public Affairs David Mould said: "These emerging on-demand technologies are changing the way people stay informed about the world around them. We're committed to making information about space exploration more accessible to audiences that may not normally get a chance to experience the exciting things we do."