Crashing to success: What we know and don't know about Starship's third test flight

Once again, Starship’s integrated test flight was a huge spectacle for spaceflight enthusiasts, with Ship 28 cutting through a gloving plasma in incredible footage never seen in real-time like this before.

However, did the flight meet its objectives? SpaceX’s debrief confirms the third integrated flight indeed reached several important milestones and moved the goalposts for Starship once again. Yet, there were still some near-misses during the test mission, while some other objectives still need clarification by SpaceX.

You can re-watch the official launch coverage here:

Starship lifted off from Boca Chica, Texas on Thursday morning. The good news already is that for the second time, all 33 Raptor engines of the Super Heavy booster completed a full-duration burn.

Firing tens of rocket engines simultaneously and maintaining the stability of the vehicle through the ascending phase is very challenging. Soviets failed to achieve this with their heavy-lift N1 rocket 31 engines. However, SpaceX has already a lot of experience thanks to their Falcon Heavy rocket with 27 Merlin 1D engines.

A few minutes into the flight, the rocket successfully completed the hot-stagging during which the Super Heavy booster separated from Starship. This was already achieved during the previous flight, but this time around, the booster was also able to complete the following boostback burn.

The boostback burn sent the Super Heavy toward the Gulf of Mexico where it was meant to soft-land. However, the onboard real-time footage showed Super Heavy starting to wobble. A few of the center engines reignited and shut down again before the communication link was lost and the loss of the booster was confirmed.

In the debrief, SpaceX specified that “the booster’s flight concluded at approximately 462 meters in altitude.” But despite that, we could see an interesting conversation on social media by enthusiasts and scientists analyzing the last seconds of onboard footage that was broadcast live.

In the last moments, we could indeed see something reminiscent of ocean waters, however the distant clouds imply the vehicle is higher in altitude than we think. Some even speculated that, given the high speed of the falling vehicle, 462 meters is well within deviation between the ocean level and the point of the last data transmission.

It very well might be one of many interesting bits that we could hear SpaceX or Elon Musk comment on later on the road toward flight four.

Even though the booster didn’t land, the attempt will provide precious data for SpaceX's engineers. It was the first time that Super Heavy descended vertically toward the surface and flight data will help SpaceX to keep the booster under control and to slow down in time.

Meanwhile, the Starship continued its way to orbital velocity which it reached later in the flight. However, once the six Raptor engines shut down, the vehicle experienced a roll through the coast phase of the sub-orbital flight.

The roll rate was high enough to prevent SpaceX from reaching another important milestone, the mid-flight re-ignition of the Raptor engine. This objective will be surely moved to flight four.

Roll rates, however, didn’t prevent a crucial demonstration of on-orbit propellant transfer between the main and the header tank. SpaceX was conducting it as part of a contract with NASA worth $53 million.

“Propellant transfer demo complete,” SpaceX tweeted during the flight. However, this doesn’t mean the demo was successful. In the debrief, the company wrote that the transfer was initiated but didn’t specifically say it succeeded.

“Results from these demonstrations will come after postflight data review is complete,” said SpaceX referring not only to the propellant transfer but also to the test of the payload door, the mechanism first time present on the Starship.

The ship died during an attempt to re-enter the atmosphere and descend toward the waters of the Indian Ocean, its planned landing site where it was to make a high-velocity splashdown. This was the first time Starship’s heatshield tiles would be put to the test.

However, as we could have observed the rolling vehicle, Starship was visibly struggling to keep its orientation for the descent, especially keeping the heatshield-protected belly of the spacecraft facing the gloving plasma.

Once again, though, the flight data that SpaceX can’t obtain in computer simulations are invaluable to understanding the challenges of hypersonic re-entry and the changes that are needed for future iterations of Starship:

“This rapid iterative development approach has been the basis for all of SpaceX’s major innovative advancements, including Falcon, Dragon, and Starlink. Recursive improvement is essential as we work to build a fully reusable transportation system capable of carrying both crew and cargo to Earth orbit, help humanity return to the Moon, and ultimately travel to Mars and beyond.”

Elon Musk hopes SpaceX can fly Starship more frequently in 2024 after being limited to just two flights in 2023. “Hopefully, at least 6 more flights this year,” he said.