SpaceX Has Realized That Starship Is Too Heavy to Land, So It’s Going to Try Something New in a Few Days

  • To date, the Starship's Super Heavy stage has never completed its landing maneuver.

  • The hot-stage separation ring added 9 tons to the rocket, and that’s a problem for SpaceX.

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Starship's fourth flight test is tentatively scheduled for Wednesday, June 5. The world’s largest and most powerful rocket will maintain its previous flight pattern, but SpaceX needs to fix a weight problem in order to prove its viability.

Hot-stage separation ring. Starship’s first flight test was a complete disaster. Not only did it damage the launch pad, but the launch vehicle’s two stages also failed to separate. To prevent this from happening again, SpaceX has added a ring with slits between the stages to enable what’s known as a hot separation.

In the second test flight and onwards, the Starship spacecraft fires its engines to move away from the Super Heavy booster. The hot separation ring is designed to protect the booster from the exhaust of the spacecraft’s engines. As the Starship continues its journey into space, the Super Heavy booster shifts to a vertical position for landing.

A complex maneuver. The Super Heavy hasn’t yet successfully completed this landing maneuver. The plan is for it to practice landing in the ocean using its aerodynamic grids and moving engines, similar to the process SpaceX plans to use at the launch tower, where mechanical arms will catch the booster before it touches down.

The test has gone wrong a few times due to a blockage in the engines’ oxygen inlet filters caused by propellant agitation after separation. SpaceX plans to solve this issue with better filtering systems, but another problem that arises is preventing the maneuver from being successfully completed.

Too heavy to land. The hot separation ring added 9 tons to the Super Heavy, a small amount compared to the booster’s 250-ton mass, but about half the weight of a SpaceX’s Falcon 9 first stage.

The Super Heavy’s oxygen and methane landing tanks are different from those used for liftoff. They’re smaller than the main tanks and weren’t designed to accommodate the weight of the ring. As a result, the rocket is too heavy to complete its landing maneuver.

The solution: Eject the ring. SpaceX plans to address this issue by jettisoning the hot separation ring mid-flight. According to Starship’s fourth flight test schedule, the ring will separate from the Super Heavy at 3 minutes and 54 seconds, 2 seconds after the engines that bring the booster into landing position are shut down.

It’ll be interesting to see if any camera captures this moment, although it may be challenging for the onboard cameras to do so from that angle. However, this won’t be the definitive solution. SpaceX intends to reduce the weight of the Starship and alter the design of the internal tanks for the V2 version of the rocket.

Starship 2 won’t only resolve the weight issues of Starship 1 but will also be capable of launching twice as much cargo, or 100 tons, according to the company. This cargo capacity is what SpaceX initially promised the Starship would be able to carry. However, it was recently revealed that the current version of Starship can only take off with 50 tons, which is less than what SpaceX’s Falcon Heavy is capable of launching.

Image | SpaceX

Related | Elon Musk Reveals Details About Starship’s Next Flight. It’s Not Good News for Those With Little Patience

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