With a deafening roar that rattled windows, SpaceX — the rocket company founded by Elon Musk — fired up its new Mars rocket-ship prototype for the first time Wednesday.

The roughly 60-foot-tall stainless-steel rocket ship, called the "Starhopper" (previously the "Test Hopper"), is a basic prototype of a much larger vehicle called Starship. When completed, perhaps in the early 2020s, the two-stage launcher may stand perhaps 400 feet tall and be capable of landing its nearly 200-foot-tall spaceship on Mars.

The Starhopper prototype gave a full-throated yet brief one-second roar of its sole Raptor engine at 7:57 p.m. CDT on Wednesday, based on Business Insider's eyewitness account.

"Starhopper completed tethered hop. All systems green," Musk tweetedshortly after the brief firing here on Brazos Island. SpaceX had planned to test the rocket ship earlier this month but had issues with ice-crystal formation in the engine.