SpaceX is considering numerous options for the upcoming Starship test schedule as the goal of reaching orbit by the summer becomes increasingly realistic.
Following Starship SN15’s successful test, options include reflying the vehicle to achieve key reusability objectives, launch SN16 to a higher altitude, or push straight through to orbital testing on Super Heavy.
Testing numerous modifications to the vehicle, Starship SN15 validated the improvements by conducting a smooth launch site campaign without the need to swap out a Raptor engine following its static fire tests.
Once SN15 was pressed into the countdown, marked by the visible sign of the CH4 (Liquid Methane) condenser being turned on, the count proceeded smoothly without any obvious mini-holds observed during previous launches.
Rising into a thick cloud layer under the power of Raptors SN54, SN61, and SN66 – along with some intermittent onboard views as a likely result of the thick clouds – most of the powered ascent was obscured from view.
The vehicle once again conducted the hover before then flipping to transition for the “bellyflop” return to the launch site, with another stable descent with good control via its aero surfaces. This element of flight has been one of the key successes per Starship’s initial test objectives.
Per SpaceX’s Jon Insprucker’s pre-launch commentary, SN15 was expected to conduct a three-engine flip, followed by a single-engine landing. However, onboard views showed two engines relit for the flip, remaining on through to touchdown.
No official reason has been provided, although Starship’s flight computer does hold the option to alter the engine ignition sequence. In addition, it has been suggested that one engine may have suffered an issue during ascent, resulting in SN15 opting not to select that engine for the relight ahead of landing.
SpaceX Chief Designer Elon Musk had previously referred to an option-based selection process, specifically on the point of redundancy. For example, Starship can relight all three engines, then immediately deselect the engine with the least lever arm as a way of ensuring the maneuver is completed.
Pending official information, the end result will be considered a bonus based on SN15 ultimately succeeding with the flip and landing via the two selected engines.
Although there was also a small fire near the aft of the vehicle post-landing, pad fire suppression hoses successfully put out the flames as the vehicle conducted safing operations, as observed via the well-known double depress vent.
Now, with SN15 secured on the landing pad, SpaceX engineers will be able to fully examine a flown Starship, which will provide valuable data for the test program.
It was considered as likely, based on the numerous Starships waiting in the wings, that SN15 would be retired to become a lawn ornament at SpaceX Starbase, or even scrapped, as seen with the 150-meter hop twins, SN5 and SN6.
Then Musk tweeted a potential plan to refly SN15. His use of “might” also provided clues…