* Astronomy

SpaceX 'Mars' rocket engine tested

Private firm SpaceX has carried out its first test of the Raptor rocket engine, designed to send humans to Mars.
SpaceX founder Elon Musk announced that the engine had been fired at the company's facility in McGregor, Texas.
If his vision is realised, it could power a super-heavy launch vehicle that would transport people to the Red Planet in coming decades.
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