Less than a week ago, SpaceX almost succeeded in completing a flawless test flight for the Starship SN10. And things were looking up until a few moments after a successful ascent and touchdown back to earth. Just like the SN8 and SN9 predecessors before it, SN10 too met a fiery, explosive ending.
It was unclear why the rocket exploded, especially after it had touched down and remained stationary for close to a minute. SpaceX founder and CEO, Elon Musk, has now cleared up some confusion on that front. Musk tweeted that "the SN10 engine was low on thrust due (probably) to partial helium ingestion from the fuel header tank." And that the prototype plummeted towards the earth at an impact velocity of 10m/s that crushed some legs and parts of the skirt.
SN10 engine was low on thrust due (probably) to partial helium ingestion from fuel header tank. Impact of 10m/s crushed legs & part of skirt. Multiple fixes in work for SN11.— Elon Musk (@elonmusk) March 9, 2021
As spotted by Engadget, Chris Bergin of NASA Spaceflight pointed out that the helium ingestion was caused by the pressurization system that was added to the CH4 tank to prevent what caused the SN8 to explode. Musk replied to Bergin stating that this was a reasonable point, and that "...if autogenous pressurization had been used, CH4 bubbles would most likely have reverted to liquid. Helium in header was used to prevent ullage collapse from slosh, which happened in prior flight. My fault for approving. Sounded good at the time."
Fair point. If autogenous pressurization had been used, CH4 bubbles would most likely have reverted to liquid.— Elon Musk (@elonmusk) March 9, 2021
Helium in header was used to prevent ullage collapse from slosh, which happened in prior flight. My fault for approving. Sounded good at the time.
Despite this, the SN10's touchdown represents a big step forward for the Starship program and SpaceX at large. The firm was quick on bringing the next prototype, the SN11, to the stand at Boca Chica, preparing for its test flight sometime later. As Austin Barnard photographed, the team of engineers on-site inspected every landing leg of the SN11. SpaceX hopes that the insight gained from its predecessors, including the SN10, will be used to do away with past mistakes and progress towards a successful test flight for the SN11.