Propellant Dump Gone Wrong Caused Recent Starship Explosion, Musk Says

Elon Musk recently revealed that the explosion of the Starship’s upper stage this past November during its second test flight was caused by a propellant dump gone wrong. Despite this setback, the incident will not impact the megarocket’s upcoming scheduled flight in February, according to the SpaceX CEO.

, which took place on November 18, 2023, was a notable improvement over the , performed several months earlier on April 20. However, instead of a single explosion like the first test, this experimental rocket produced two separate explosions during the second; the Super Heavy booster and the Starship upper stage exploded approximately five minutes apart during the eight minute mission.

The booster blew up real good in the immediate moments following stage separation. That obviously wasn’t the intention, but SpaceX did manage to perform its first ever hot staging procedure, meant to ease the transition between stages. The upper stage, freed from its booster, flew independently for several minutes before it too ended its journey with a bang.

At the time, SpaceX said the “rapid unscheduled disassembly” was the result of the flight termination system having to kick in, but the exact reason for the anomaly wasn’t given. SpaceX CEO Elon Musk finally provided more information while speaking to company employees on January 11 during an held at the Starbase test site in Boca Chica, Texas.

The explosion, he said, was the result of liquid oxygen having to be vented from Starship as the vehicle neared the end of its engine burn. This venting procedure was performed on account of Starship not carrying any cargo, he said. “Flight 2 actually almost made it to orbit,” Musk claimed. Had Starship been filled with cargo, “it would have made it to orbit because the reason that it actually didn’t quite make it to orbit was we vented the liquid oxygen, and the liquid oxygen ultimately led to a fire and an explosion.” I’m not entirely sure why Musk says Starship nearly made it to “orbit,” as that was never the intention.

For this distinctly suborbital flight, the rocket’s upper stage was to travel across the globe and perform a hard ocean landing near Hawaii, without entering orbit or performing a full circumnavigation of Earth. Musk’s embellishment notwithstanding, this venting procedure would normally be unnecessary.

Typically, with cargo on board, the Raptor engines would consume all the fuel during its second stage lifting, eliminating the need for venting. However, the empty Starship resulted in surplus propellant that had to be discharged. Encouragingly for SpaceX, this isn’t a major problem, and the issue shouldn’t affect the next launch.

“I think we’ve got a really good shot of reaching orbit with [the third flight],” Musk said. And by “orbit,” Musk once again means suborbit, unless the have changed. Musk did not elaborate as to why the venting caused the fire and the explosion. More details on this matter would’ve been nice, as that doesn’t seem to be the kind of thing you want happening, test or not.

He also didn’t clarify the reason for not including a dummy payload in the flight to mimic the weight of actual payloads, nor did he speak to the failure of the Super Heavy booster. As for Starship’s third flight, that could happen in February, as Jessica Jensen, vice president of customer operations and integration at SpaceX, during a NASA press conference on January 9.

The requisite hardware is expected to be secured this month; the company now just needs to acquire a Federal Aviation Administration license. During the third demonstration mission, SpaceX aims to conduct an in space engine burn using the header tank at the top of the rocket, as Musk explained. This is to demonstrate reentry capabilities.

The company is also planning to conduct an initial test of transferring propellant from the header tank to the main tank, a process being developed with NASA funding, as it’s a requirement for the Artemis missions. Ultimately, the goal is to transfer propellant between two Starships in orbit. The first such ship to ship transfer test could occur by the end of this year or “certainly by next year,” Musk said.

Once developed, Starship will serve as a fully reusable launch and spacecraft system designed for low cost, high capacity missions to Earth orbit, the Moon, Mars, and other destinations. Starship is significant for NASA and the wider space industry, as it’s poised to introduce new options for deep space missions, such as the Artemis program for exploring the Moon.

This could mark a turning point in space exploration, expanding opportunities for scientific research and commercial ventures in space..