The European comet-chasing probe, Rosetta, has been successfully launched at the third attempt from a site in French Guiana.
Two previous efforts to launch the €900m craft were halted last week because of high winds and technical problems.
In another development, the US space agency, NASA, is reported to have found strong evidence that water once flowed on Mars.
The presence of water makes it much more likely that the planet once supported life.
