SpaceX launched its shiny, bullet-shaped, straight-out-of-science fiction Starship several miles into the air from a remote corner of Texas on Wednesday, but the six-minute test flight ended in an explosive fireball at touchdown.

It was the highest and most elaborate flight yet for the rocketship that CEO Elon Musk says could carry people to Mars in as little as six years.

This latest prototype — the first one equipped with a nose cone, body flaps and three engines — was shooting for an altitude of up to 12.5 kilometres. That's almost 100 times higher than previous hops and skimming the stratosphere.

Starship seemed to hit the mark or at least come close. There was no immediate word from SpaceX on how high it went.

Musk hailed the test as a "successful ascent."

"Mars, here we come!" Musk tweeted following the explosion.

The full-scale, stainless steel model — 50 metres tall and nine metres in diameter — soared out over the Gulf of Mexico.

After about five minutes, it flipped sideways as planned and descended in a free-fall back to the southeastern tip of Texas near the Mexican border.

The Raptor engines reignited for braking and the rocket tilted back upright. Upon touching down, however, the rocketship became engulfed in flames and ruptured, parts scattering.

The entire flight — as dramatic and flashy as it gets, even by SpaceX standards — lasted just over six minutes and 40 seconds.

SpaceX broadcast the sunset demo live on its website; repeated delays over the past week and a last-second engine abort Tuesday heightened the excitement among space fans.

"Awesome test. Congratulations Starship team!" read a scroll across the screen.

Musk kept expectations low going into this first high-altitude attempt by Starship, cautioning earlier this week there was "probably" a 1-in-3 chance of complete success.

Amazon's Jeff Bezos, who founded the Blue Origin rocket company, offered swift congratulations.

"Anybody who knows how hard this stuff is is impressed by today's Starship test."

Two lower, shorter test flights earlier this year from Boca Chica, Texas — a quiet coastal village before SpaceX moved in — used more rudimentary versions of Starship.

Essentially cylindrical cans with cone tops and single Raptor engines, these early vehicles reached altitudes of 150 metres.

An even earlier model, the short and squat Starhopper, made a tiny tethered hop in 2019, followed by two increasingly higher climbs.

Wednesday's test followed SpaceX's latest space station supply run for NASA by three days, and the company's second astronaut flight by less than a month from Florida's Kennedy Space Center.

• Elon Musk reveals SpaceX Starship

SpaceX intends to use Starship to put massive satellites into orbit around Earth, besides delivering people and cargo to the moon and Mars. Earlier this year, SpaceX was one of three prime contractors chosen by NASA to develop lunar landers capable of getting astronauts on the moon by 2024.

Right before Wednesday's launch, NASA introduced the 18 U.S. astronauts who will train for the Artemis moon-landing program.