Engineers and technicians at the SpaceX Starbase in Boca Chica, Texas, are working on getting the fully-stacked Starship and Super Heavy prototypes ready for their orbital launch test. The most recent step consisted of a static fire test with the BN7 Super Heavy prototype, where the booster was placed on the orbital launch pad and fired one of its thirty-three Raptor 2 engines. News of the test was shared via SpaceX’s official Twitter account and showed the BN7 blasting the launch pad, leading many to wonder what the orbital launch test will look like!
Team at Starbase completed a single Raptor engine static fire test of Super Heavy Booster 7 on the orbital launch pad pic.twitter.com/16R7eE985V
This successful static fire test happened about a month after a previous attempt resulted in an explosion on the landing pad. Known as an “engine spin start test” (aka. “spill test”), it consisted of fuel being pumped through the booster’s fuel lines and engine system without ignition. Unfortunately, the spilling fuel caught fire, causing an explosion that damaged the landing pad and booster. Luckily, ground teams inspected the BN7 and revealed that the damage was not too significant.
Musk then told the news agency Reuters that BN7 would be “returning to the launch stand probably next week” (pending another inspection in the Starbase High Bay). He also took to Twitter to explain the cause of the explosion, stating that the fuel evaporated and created a “fuel-air explosion risk in a partially oxygen atmosphere like Earth.” A Twitter user then asked if it would be possible to burn off leaked fuel before ignition, something the Space Shuttle did with its Radial Outward Firing Igniters (ROFIs) to burn off evaporating liquid hydrogen.
“That is one of the things we will be doing going forward,” Musk tweeted in response. “This particular issue, however, was specific to the engine spin start test (Raptor has a complex start sequence). Going forward, we won’t do a spin start test with all 33 engines at once.” Musk also tweeted that another static fire test could be attempted “as soon as next month” – a prediction that has proven eerily accurate! The BN7 returned to the launch pad by Aug. 6th to perform this most-recent static fire test – which involved no spin start and igniting only one engine.
In terms of the overall timetable, Musk indicated days before the booster’s return that, “A successful orbital flight is probably between 1 and 12 months from now.” The word “successful” is undoubtedly emphasized because with any inaugural space flight, the learning curve is immense, and accidents are known to happen. This is precisely why SpaceX adopted the rapid-prototyping and testing model they’ve used to develop the Starship and Superheavy, which was intended to maximize the amount of launch test data they could gather.
These tests informed the evolving design of the Starship and the maneuvers it conducted during descent and landing. In addition, the length of this window suggests that Musk is anticipating that the initial attempt may not succeed and that SpaceX will have to make further attempts with other fully-loaded and stacked prototypes. Nevertheless, a window of a month to a year is a pretty vague one. But given recent events and the delays they’ve imposed, an orbital flight in 2023 seems like an optimistic appraisal right now.
As always, Musk and the company he founded are getting there one foot at a time. Or, in this case, several explosions and one successful flight at a time!
Further Reading: Reuters, Yahoo Finance, Twhttps://twitter.com/SpaceX/status/1557147770586144768itter