NASA: tests to Em-Drive space engine were completed, which produces energy from the vacuum by exploiting some of the physical processes. The device is able to propel spacecraft without fuel, producing energy from nothing. There remains a lot of distrust about the tests, because the engine is producing energy, but very weakly. If true, and the engine was working properly, you could go to Mars in a few days at very low cost, producing energy from nothing. It 'a great revolution, will hopefully be improved and used commercially.
Written by: Maurizio Savigni