"Those hopper flights would go up to an altitude of several kilometers. "We'll do flights of increasing complexity," he said last month, including tests of heat shield technology.
Musk didn't provide new testing details in his SXSW interview, and offered a cautionary note about schedules. "People have told me that my timelines historically have been optimistic," he said. "So I'm trying to recalibrate to some degree here." That echoed his comments in Ausralia last year, where he described a schedule that called for the launch of the first BFR missions to Mars in 2022 "aspirational.
The interview covered a wide range of other topics, from his leadership of electric vehicle company Tesla to founding the tunneling startup The Boring Company to his concerns about artificial intelligence. He also stressed his worries about a war or other calamity setting back civilization on Earth, a motivation for establishing a presence on Mars." space.com
The Big Falcon Rocket is Musk's space ship for the establishment of a first permanent colony on Mars. He is building a vessel that will have a reusable first stage and a second stage that is the Mars lander. He intends to start testing the second stage as a separate unit next year in what he call "hopper" jumps with flights of increasing difficulty proceeding to LEO flights fairly soon. Because of the re usability factor a launch to LEO is expected to cost $6 million. This is a low relative cost. Interestingly he plans to produce fuel for the rocket and food for the crew on the surface of Mars.
At the same time he says he hopes that SpaceX' success in the Mars effort will bring more commercial players into this business. pl