SpaceX has last week announced the next target date for it’s third integrated test flight of the Starship. The next step is a small one, but has a much higher likelihood of success.
The US Federal Aviation Administration (FAA) last week published its findings into SpaceX’s second orbital flight test of Starship (OFT-2), which has opened the door for the company to push towards its next test flight. The mishap investigation was a mandatory (and expected) step after the last flight, which did not go to plan. The mishap report, which it is important to note was led by SpaceX, detailed 17 corrective steps that had been identified as part of the investigation. With the mishap investigation hurdle cleared, OFT-3 is targeted for no earlier than 14 March.
OFT-2 was the long awaited second orbital test flight for starship, which was launched with a plethora of fixes and corrective actions that had been made on the super heavy booster, Starship itself and ground support systems after OFT-1. When the OFT-1 flight launched, the launch pad had been completely destroyed by the more than 74,000 KN of thrust produced by the booster. The team had installed a new metal launch plate with an integrated water deluge flame deflection system to protect it, which worked perfectly on OFT-2. The destruction of the launch pad on OFT-1 was largely to blame for the failure of launch, having caused substantial damage to the base of the booster and raptor engines, and once that obstacle had been overcome, the vehicle had a clear shot at proving itself in flight.
During OFT-2 the vehicle launched perfectly, with all 33 raptor engines firing continuously in the first phase of flight, reaching 150 km in altitude and 24,000 km/h (3,000 km/h short of orbital velocity). Once a subset of raptors had been shut down in preparation for hot staging (a method of vehicle and booster separation that involved burning the vehicle’s engines in order to push it away from the booster), multiple successive engine failures on the booster activated the in-flight termination system, and the booster was destroyed in flight.
The Starship vehicle went on its planned course of flight before it too had a failure. As part of SpaceX’s plan for the flight, Starship had to perform a planned Liquid Oxygen (LOX) dump, as an excess of LOX had been loaded for the flight to mimic a production standard propellant load. The LOX dump had to be performed before the re-entry of the vehicle could be attempted. As soon as the dump was performed however, a leak and subsequent fire developed in the engine compartment. It is speculated that the fire burnt through critical wiring that connected the engines to the flight computers, leading to loss of control. The FAA had as part of their report detailed corrective measure for OFT-3, which included reinforcing and simplifying the sections on the ship that had been identified as vulnerabilities in this regard. The report also stated that additional fire protection was needed around vulnerable areas, and changes were to be made to prevent leaks. These changes could include but are not limited to:
- Fire resistant insulation around flight critical wiring
- Better routing of wires through lower risk areas
- Improved seals, valves and tubing to prevent leakage
The LOX dump has also been eliminated for OFT-3 which should further mitigate the risk of another failure.
The question now remains: will OFT-3 be a success? The answer is yes, likely.
OFT-3 is slated to fly on an orbital trajectory that will take it from Boca Chica in Texas and will maintain a course over the Atlantic, stretching from just North of South America, eventually crossing into Africa, passing over Botswana and South Africa before attempting re-entry in the Indian Ocean just North of Australia.
The corrective measures stipulated in the FAA report have already been made on Starship Sn28 and super heavy booster 10, and a full wet dress rehearsal has taken place, with full propellant load having been done in a mere 50 minutes, 40 minutes quicker than any previous fueling attempt. The reduction in fueling time came after upgrades to ground systems and has significant impact on the mission. If the propellant load time is reduced it effectively means that there is less time for the super-chilled gas to warm up, and can thus stay colder before launch. With colder temperatures the density of those gasses are reduced, and more propellant can thus be loaded, increasing overall performance of the booster.
Barring any major technical malfunctions, OFT-3 stands a very good chance of being the most successful orbital starship flight to date. The data that can be gathered during this flight will pave the way for SpaceX to continue making more iterative design improvements on Starship, and the company will move another step closer to flying the Starship with humans on board in future. Curious what Starship’s first crewed mission could look like? See our recent write up on the Polaris missions for a preview!
