Starship Lifts Off, But Ends in a RUD

Starship Lifts Off, But Ends in a RUD

SpaceX’s Starship rocket left the launch pad this morning, but ended in a fireball a few minutes later when the first and second stages failed to separate. The combination exploded — what is humorously referred to as a Rapid Unscheduled Disassembly or RUD. Nevertheless, SpaceX cheered the milestones they did achieve — getting off the launch pad and through a critical point called maximum dynamic pressure or Max Q. The FAA says it will oversee the investigation into what went wrong and determine when Starship can return to flight from a public safety perspective.

Today was the second attempt to launch Starship, a two-stage vehicle that is confusingly named. The first stage is Super Heavy and the second stage is Starship, but the combination of the two is also called Starship.

The first try on Monday scrubbed because of a frozen valve in the propellant system.

Today’s countdown went smoothly all the way to 40 seconds before launch, a pre-planned point at which a hold could be called if needed to deal with any last moment issues. The flight director chose to exercise that hold to complete final purging of the second stage. The count resumed five minutes later and at 9:33 am ET (8:33 am local time at the launch site) the 120-meter (394-foot) tall, 9-meter (29.5-foot) diameter rocket filled with 10 million pounds of methane and liquid oxygen lifted off from Starbase in Boca Chica, TX.

The first stage is powered by 33 Raptor engines designed and built by SpaceX. They generate 16 million pounds of thrust, more than twice the 7.6 million pounds of thrust of the Saturn V rocket that sent Apollo crews to the Moon and almost twice the 8.8 million pounds of thrust for NASA’s new Moon rocket, the Space Launch System. It is the most powerful rocket built to date.

At first, all appeared well as the rocket ascended and flew out over the Gulf of Mexico.

SpaceX’s commentators said all along they would consider just getting off the pad to be a success for this first test flight of the integrated rocket. Any additional milestones would be a bonus. SpaceX employees on the webcast could be heard uproariously cheering as the rocket passed through Max Q, a critical point when aerodynamic forces on the rocket are at their highest.

A SpaceX camera view of the bottom of the Super Heavy first stage showed that a few of the 33 Raptor engines were not lit, however. The outer ring has 20 engines with another 13 in the center.

The bottom of the Super Heavy rocket (Starship’s first stage) after passing through Max Q on its first launch, April 20, 2023.  Only 15 of the 20 engines in the outer ring and 11 of the 13 in the center appear to be lit. Screengrab.

Shortly afterward, the first and second stages were supposed to separate, with Super Heavy making a manuever to turn around and prepare for landing and Starship continuing on its test flight around the globe to splash down near Hawaii. Both stages are designed to be reusable once operational, but neither was intended to make a survivable landing this time.

However, the two stages failed to separate and the entire assembly began spinning. On the webscast, SpaceX’s John Insprucker acknowledged “This does not appear to be a nominal situation.”  Moments later, it exploded.

Starship explodes almost four minutes after launch over the Gulf of Mexico on its first integrated test flight. The first and second stages did not separate. April 20, 2023. Screengrab.

Space X later said the explosion was caused by commanding the Flight Termination System (FTS) on both Super Heavy and Starship. In a statement on its website, the company said the rocket reached an altitude of 39 kilometers (about 24 miles), but experienced “multiple engine outs during the flight test, lost altitude, and began to tumble.”

Source: SpaceX website, April 20, 2023.

The FAA is responsible for public safety of commercial space launches and issued a statement that there were no reports of public injuries or property damage. It will oversee the investigation into what happened and make a determination when, from a public safety perspective, SpaceX can try again.

Source: FAA emailed statement, April 20, 2023.

In a subsequent email, the FAA said “SpaceX reported to the FAA that the Autonomous Flight Termination System activated as intended.”

NOAA’s GOES weather satellite captured images of the flight and the RUD.

This was the first flight of Super Heavy, but a Starship second stage prototype had five test flights in 2020-2021. The first four ended in flames. SpaceX took it all in stride and each time got ready for the next test flight.

SpaceX founder and CEO Elon Musk seemed to take today’s results the same way, congratulating his team “on an exciting test launch” and vowing to try again “in a few months.”

Starship is not only critical to SpaceX’s own business plans for launching second-generation Starlink satellites and Musk’s vision of sending millions of people to Mars, but for NASA’s plan to return astronauts to the Moon. NASA selected Starship as the Human Landing System for at least the first two Artemis lunar landing missions, Artemis III and Artemis IV.

NASA Administrator Bill Nelson tweeted an encouraging message, noting that great achievements require “some level of calculated risk, because with great risk comes great reward.”

This article has been updated.

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