The US company SpaceX is working on the first-ever reusable rocket to launch to space and back, with the goal of one day helping humans colonize Mars, founder Elon Musk said Thursday.

The vehicle would be a reusable version of the Falcon 9 rocket which SpaceX used to propel its Dragon space capsule to low Earth-orbit on a test mission last year. Its first cargo trip to the International Space Station is set for January.

Being able to reuse the rocket would save tens of millions of dollars and would bring the notion of making trips to visit or even live on other planets, namely Mars, closer to reality, Musk told reporters at the National Press Club.

"A fully and rapidly reusable system is fully required for life to become multi-planetary, for us to establish life on Mars," Musk said. "If planes were not reusable, very few people would fly."

Currently, a Falcon rocket costs between 50-60 million dollars to build and launch, with fuel and oxygen costs making up just 200,000 dollars. Then, it is lost forever as it burns up on re-entry into Earth's atmosphere.

If engineers could reuse a rocket, that would bring the capital cost of a launch way down and "allow for about a 100 fold reduction in launch costs," he said.

Maximum Speed - 6106 km/h