And, the Super Heavy rocket is expected to require as many as 31 of these engines.
Starship - previously known as BFR, Big Falcon Rocket, or the Big F***ing Rocket - is the crux of Musk's plans to send humans to Mars.
A prototype version of the Starship, dubbed the Starship Hopper, is under construction at another SpaceX facility on South Texas' Gulf Coast.
GM layoffs expected to cut more than 4K white-collar workers
GM said its decision to cut almost 14,000 jobs and idle five plants in North America will save $2 billion to $2.5 billion in 2019. It's also planning to shut down four manufacturing plants in the U.S. and one in Canada with more than 6,000 hourly workers.
As to why the flames are iridescent, Musk explains in a follow-up tweet that, "Engine use methox torch igniters".
"First firing of Starship Raptor flight engine!" As Business Insider reports, the engine underwent a radical redesign and is capable of 200 metric tons of thrust.
'Next versions will split to vacuum-optimized (380+ sec Isp) & sea level-thrust optimized (~250 ton)'. Development of the BE-4 will be completed later year, Bob Smith, chief executive of Blue Origin, said at a January 25 groundbreaking for a new factory in Huntsville, Alabama, that will produce the engine for both United Launch Alliance's Vulcan and the company's own New Glenn rocket.
Those unforeseen issues include high winds the toppled the upper, nose cone section of the vehicle last month.