SpaceX's new Starship re-tries 1st launch on Super Heavy rocket

Elon Musk's SpaceX aimed on Thursday to launch the company's next-generation Starship spacecraft atop its powerful Super Heavy rocket for the first time, on a highly anticipated but brief crewless test flight from the Gulf Coast of Texas.

Final preparations were underway at the company's Starbase launch site east of Brownsville, Texas, for a liftoff three days after an earlier launch attempt was scrubbed near the end of the countdown due to a frozen pressurization valve.

Barring further show-stoppers on Thursday, the two-stage rocket ship, standing taller than the Statue of Liberty at 120 metres high, was due to blast off between 9:30 and 10:30 a.m. ET on a planned 90-minute debut flight into space, just shy of Earth orbit.

Getting the newly combined Starship and booster rocket off the ground for the first time would represent a key milestone in SpaceX's ambition of sending humans back to the moon and ultimately on to Mars — playing a pivotal role in NASA's newly inaugurated human space flight program, Artemis.

A successful flight would instantly rank the Starship system as the most powerful launch vehicle on Earth.

Both the lower-stage Super Heavy booster and the upper-stage Starship vessel it would carry to space are designed as reusable components, capable of flying back to Earth for soft landings — a manoeuvre that has become routine in dozens of missions for SpaceX's smaller orbital-class Falcon 9 rocket.

But neither stage would be recovered from Thursday's launch. Instead, both parts will end their introductory flight to space with crash landings at sea. The lower stage will fall into the Gulf of Mexico after separating from the upper stage, which will come down in the Pacific Ocean after achieving nearly one full Earth orbit.

Prototypes of the Starship cruise vessel have made five sub-space test flights to altitudes of 10 kilometres in recent years, but the booster rocket has never left the ground.

In February, SpaceX conducted a test-firing of the Super Heavy, igniting 31 of its 33 engines for roughly 10 seconds with the rocket bolted in place vertically atop a platform.

The U.S. Federal Aviation Administration last Friday granted a licence for the first test flight of the fully stacked rocket system, clearing a final regulatory hurdle for the long-awaited launch.

The SpaceX announcement this week on Twitter that it planned a second launch attempt on April 20, after the first was scrubbed, amused many of Musk's fans and detractors alike.

The tweet set off a flurry of jokes on the social media platform making reference to 4/20 as a date widely associated with cannabis culture, and to the notoriety Musk gained in 2018 for smoking marijuana on a live web show.

Musk, who purchased Twitter last year for $44 billion, is the founder, CEO and chief engineer of SpaceX. He also is chief executive of electric carmaker Tesla Inc.

If all goes as planned on Thursday, the Starship will ascend on a flight most of the way around the Earth before it re-enters the atmosphere and free-falls into the Pacific at supersonic speed, about 97 kilometres off the coast of the northern Hawaiian islands.