when spacex was getting started, the first and last men to walk on the moon testified before congress against it. gene cernan told congress commercial space companies "do not yet know what they don't know." he said the boeings and lockheed martins were "the folks who have been working on everything we've done for the last 50 years. they know how it can be done." neil armstrong said he was "not confident" the newcomers could achieve their goals. together with jim lovell they warned it would put america on "a long downward slide to mediocrity." spacex now launches more rockets than every country on earth combined. the experts will always tell you it can't be done. build it anyway!