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Despite tentative preservation plans, SpaceX completely scrapped the wreckage of the first prototype high-altitude spacecraft, clearing the landing zone it touched for the imminent launch of its successor.
Known as serial number 8 or SN8, the Starship prototype was the first of any type to fly beyond 150 meters (~ 500 feet), reaching an altitude of 12.5 km (~ 7.8 mi) on December 9 in its breathtaking debut. In an unexpected twist, SpaceX kept the Starship SN8’s thrust-to-weight ratio as low as possible, turning what could have been a two- or three-minute test into an almost seven-minute ordeal with three consecutive Raptor engine cuts for the ascent.
During the climax, SN8 used cold gas thrusters to rock into a belly down orientation and freely fell ~ 95% of the way back to Earth before firing two of its three Raptor engines, performing a wild return to vertical landing position and almost ensure a smooth landing. Unfortunately, about 10 to 20 seconds before this planned landing, what Musk later described as low pressure from the methane tank starved the Starship’s engines of fuel and more or less cut off any appreciable thrust, which brought on SN8 to reach its landing zone at about 40 m / s. (~ 90 mph) too fast. The rocket struck the concrete base, crumpled and exploded.
Obviously, success was one of the less likely outcomes SpaceX expected from SN8’s high-altitude debut, with Musk himself estimating the odds of total success to be only 33%. Additionally, Starship SN8 managed to achieve a low speed landing regime that Starships SN5 and SN6 demonstrated almost perfectly with consecutive 150m jumps and landings in August and September 2020.
In other words, despite the explosive ending, SN8’s high-altitude launch was a spectacular success for SpaceX’s Starship program – maybe even preferable to a perfect landing as he discovered an unexpected problem with the pressurization of the fuel tank. Beyond the failed landing, the Starship checked every box on SpaceX’s test flight list, successfully making its debut at multiple Raptors, demonstrating multiple in-flight engine shutdowns and engine re-ignitions; prove that an unprecedented “parachutist” -type landing maneuver is possible and viable; and successfully test Starship’s ability to control himself in that bellyflop orientation with massive thrusters and four flaps.
Speaking in a recent interview with Ars Technica, in the words of SpaceX’s pragmatic COO and Chairman Gwynne Shotwell, SN8’s launch debut “has [the Starship] program quite massively. According to Musk, SpaceX engineers were quickly able to determine why the Starship SN8’s methane tank was unable to maintain the fuel flow (pressure) needed for Raptor’s landing burns and quickly implemented a solution.
Instead of autogenously pressurizing with methane, the Starship SN9 will use helium to pressurize its fuel tank, serving as a temporary fix while SpaceX determines what changes need to be made to get rid of that helium kickstand. With the landing pad now cleared of Starship remains and the more or less repaired SN8 impact crater, the only thing between Starship SN9 and its own 12.5km launch debut is a test shot static triple-Raptor. Originally slated for Jan.4, SpaceX never made more than a few minutes in the attempt, while a Jan.5 save window was canceled later that evening. The test could now take place no earlier than Wednesday January 6 (NET).
Fortunately, while SpaceX was unable to save the entire wrecked nose section of the Starship SN8, the company was able to extract a largely intact nose flap. The rest of the remains were discarded on site and trucked, but it’s possible that some important SN8 components – especially the salvaged shutter – could end up on display in one or more SpaceX facilities.
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