What to Know Ahead of SpaceX’s Second Starship Test Flight on Saturday

The world’s largest and most powerful rocket ever built is slated to launch for a flight test on Saturday morning. Termed Starship, the SpaceX-built craft will lift off sometime between 8:00 a.m. and 8:20 a.m. Eastern time, if all goes according to plan.

Originally scheduled for Friday, the launch was pushed back because a small rocket part needed to be replaced, according to CNN’s Jackie Wattles. The attempt will mark the second flight test of Starship, following the rocket’s first flight in April. That time, the spacecraft, still attached to its booster, exploded about four minutes after launch.

Called Starship collectively, the nearly 400-foot-tall system consists of a spacecraft (also termed Starship) and a rocket booster called Super Heavy, which is powered by 33 engines. Both the spacecraft and its booster are meant to be reusable. SpaceX aims to eventually use Starship to carry crew and cargo to Earth orbit, the moon and Mars.

Saturday’s test is set to launch from SpaceX’s Starbase site in Boca Chica, Texas. A livestream will start 35 minutes before launch on the company’s website.

If all goes as intended, the Super Heavy booster will detach from the spacecraft less than three minutes after liftoff and head back toward the ground, landing in the Gulf of Mexico about seven minutes into the flight. The spacecraft, meanwhile, will reach speeds close to its orbital velocity of 17,000 miles per hour, but it won’t fully orbit the Earth, writes Space.com’s Mike Wall. It is scheduled to land in the Pacific Ocean 90 minutes after launching.

Preparing for launch on Saturday pic.twitter.com/gIpnubscWa

— Elon Musk (@elonmusk) November 16, 2023

During April’s test, leaking propellant in the booster caused fires, leading to a loss of communications with most of the booster engines and a loss of control of the vehicle, according to SpaceX. Some of Starship’s engines failed to start, the booster didn’t separate from the spacecraft as planned and the system started tumbling through the sky, writes the New York Times’ Kenneth Chang. Then, SpaceX intentionally detonated the spacecraft.

The explosion spewed debris nearby, damaging infrastructure and spurring environmental concerns, writes CNBC’s Sara Salinas. As a result, the Federal Aviation Administration (FAA) launched a safety investigation, and in September, it released a report naming 63 corrective actions SpaceX had to take to prevent such an accident from happening again. On Wednesday, the FAA cleared SpaceX to conduct its second test.

“The FAA determined SpaceX met all safety, environmental, policy and financial responsibility requirements” for the second launch, the FAA said in a social media post.

SpaceX says it has made several updates to the vehicle and ground infrastructure in advance of the second launch. It reinforced the launchpad foundation and added a flame detector to prevent a launchpad foundation failure, since during the first test, the booster’s engines blew the launchpad apart. Now, a new system will spray water as the engines ignite in an attempt to shield the launchpad from their energy, per CNN.

But the biggest change will be the debut of a new “hot-stage separation system,” which will use the spacecraft’s own engines to push it away from the booster.

The company has also made changes to prevent fuel leaks and fires and improve the system that causes Starship to explode, which didn’t kick in fast enough during the first test.

In August, SpaceX CEO Elon Musk wrote on social media that he predicts Starship has about a 50 percent chance of reaching orbital velocity during this test. “However, even getting to stage separation would be a win,” he added.

In 2021, NASA selected Starship to transport astronauts from lunar orbit to the moon’s surface as part of the space agency’s Artemis program. Once Starship completes its tests, SpaceX must launch at least one uncrewed mission that will land the spacecraft on the moon for it to meet NASA’s requirements.

At the end of last year, the space agency launched its Artemis 1 mission, in which an uncrewed Orion spacecraft traveled to the moon and back. Artemis 2, scheduled for no earlier than November of next year, will take four astronauts into lunar orbit. If SpaceX’s tests of Starship don’t go as planned, it could cause Artemis 3—the mission intended to land humans on the moon—to get delayed, per CNN.

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.