A tale of two missions: Starliner and Starship both achieve milestones

SpaceX and Boeing both had reasons to celebrate last night: Starship had a successful fourth flight test and Starliner docked with the International Space Station (ISS).

However, it was not plain sailing for either company.

Starship's Fourth Flight Test

SpaceX's Starship yesterday lifted off atop a Super Heavy booster from the company's facility in Boca Chica, Texas. According to SpaceX, "the payload for this mission was the data," but having the booster make a controlled splashdown and the Starship survive re-entry were obvious goals.

The launch itself went well, despite one of the 33 Raptor engines in the Super Heavy booster failing to ignite. Launch was followed by a successful hot-stage separation, in which all but three of the booster's Raptor engines were shut down, and the six second-stage engines lit to send Starship into space on its suborbital trajectory.

In a demonstration of progress from the last test, when the booster experienced a loss of control, the Super Heavy fared better this time and made a "landing" in the Gulf of Mexico, before toppling over into the ocean.

The company's boss, Elon Musk, was delighted with the result and said: "I think we should try to catch the booster with the mechazilla arms next flight!"

SpaceX plans to reuse the Super Heavy booster in future missions by having it return to the launch site and be captured by mechanical arms dubbed "Mechazilla."

As for Starship, it continued on its suborbital trajectory as planned. Surviving reentry was the next goal, and, for the most part, the vehicle made it to the ocean intact and under sufficient control to perform a flip maneuver prior to splashing down.

We say "for the most part" because viewers of video streamed from the vehicle during re-entry were treated to what appeared to be hot gases burning through a flap. The gases seemed to enter through the flap's hinge and ate through the material beneath.

Despite the damage, the Starship remained under control during entry. It was able to relight its three center Raptor engines and perform the first flip maneuver of the company's suborbital test campaign. Sixty-six minutes after launch, it made a soft splashdown in the Indian Ocean.

Musk congratulated the SpaceX team and said: "Despite loss of many tiles and a damaged flap, Starship made it all the way to a soft landing in the ocean!"

The boss also noted that future versions of Starship would shift the forward flaps leeward in an effort to improve reliability.

NASA administrator Bill Nelson offered his congratulations to SpaceX on the achievement. As well he might – NASA is depending on Starship to work as advertised as part of its plans to return astronauts to the Moon. The landing mission, Artemis III, is currently officially scheduled for "no earlier than September 2026" with Starship providing the Human Landing System (HLS).

A report from the US Government Accountability Office (GAO) late last year reckoned that NASA's schedule was ambitious and the Moon mission could slip into 2027.

Boeing's Starliner arrives at the International Space Station

While SpaceX was having another go at launching Starship, Boeing's Starliner achieved its first crewed docking with the ISS.

The spacecraft continues to suffer small issues. The helium leak that caused such consternation on the ground has been joined by several new ones. During a briefing, Steve Stich, manager for NASA's Commercial Crew Program, said that "we had way more margin than we needed" for the short demonstration mission to proceed, although the leaks will need to be addressed for longer stays.

However, helium leaks weren't the only problem as the spacecraft approached the ISS. Starliner also began having issues with its thrusters. Stich said: "We ended up losing a total of five thrusters," which resulted in controllers calling off the rendezvous until the issue was better understood.

• Boeing's Starliner makes it into orbit at long last – with human crew aboard
• NASA, Boeing opt to fly leaky thruster as-is for first crewed Starliner CST-100 mission
• SpaceX set to literally rock Florida with more and bigger Starship launches
• Clock is ticking for NASA to fix bucket of issues before next Artemis mission

The thruster problem appears to be software-related, and controllers were able to recover four of the five. Stich noted that the issues were similar to those experienced during the last uncrewed orbital flight test. "We don't quite understand why they're happening," he said.

The result was that docking was delayed after the team missed the first opportunity due to the thruster issues.

Following the successful docking, another helium leak was reported, but Stich described it as "a relatively tiny leak compared to the others."

The mission is classed as a test, and while the problems encountered so far are minor, all will need to be resolved or mitigated before Starliner's first operational mission in 2025. ®