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.
Starship SN15:
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 into SpaceX’s often fluid plans involving Starship testing.
Might try to refly SN15 soon
— Elon Musk (@elonmusk) May 7, 2021
If the option is taken, reflying SN15 will achieve another required milestone for Starship testing, given this is one of the vehicle’s unique selling points. Eventually, Starship will become rapidly reusable, with the ability to relaunch the same day as landing.
Also, during SpaceX’s pre-launch coverage of Falcon 9 B1051-10’s Starlink mission, an overview of SN15’s flight was provided along with the words “stay tuned for additional test flights in the days ahead” – as much as that could be just a case of generic wording.
Starship SN16 and SN17:
Over at the Production Site, Starship SN16 has continued to be prepared inside the High Bay.
Following the mating of its nosecone, all of its aero surfaces have now been installed, technically ready to make the roll down Highway 4 to the launch site.
Latest overview via @_brendan_lewis on Starship/Super Heavy Section Status.
Numerous options are on the table, ranging from delaying SN16’s campaign until after SN15 reflies, through tasking SN16 with a higher altitude target of 20 km, through to simply not flying the vehicle per a potential acceleration of moving to the orbital-class vehicles.
Notably, SN16 was moved deeper into the High Bay on Saturday, likely to make room for the stacking operations of the next Super Heavy prototype that will be required for the orbital tests.
The latter option would also impact SN17, which currently has its sections prepared for stacking operations – with the SN17 mid-LOX section recently staged outside the Mid Bay after pre-stacking work.
This morning Starship SN17 mid-LOX section is outside waiting to be stacked at the SpaceX Production site. 🤩🚀@NASASpaceflight pic.twitter.com/qklSdG5V4u
— Mary (@BocaChicaGal) May 8, 2021
While opting against flying at least a few more Starship hops before orbital attempts may seem unpalatable to some observers, there is evidence of SpaceX being highly focused on pushing to orbit.
Orbital Starship:
As previously reported by NASASpaceflight.com – and confirmed as “That’s our goal” by Musk on Twitter, the first orbital flight was cited in documentation as launching “with a goal to get to orbit by July 1”.
That documentation noted it would involve Starship SN20 on Super Heavy BN3.
Starship SN20 is already being assembled. It will be a key watch item to see how many TPS (Thermal Protection System) tiles they will receive – as will be required on the windward side of the vehicle to cope with the heat of re-entry.
However, as with Super Heavy BN3, the aforementioned fluid nature of SpaceX’s Starship planning could alter which vehicle takes the leap to orbit.
BN3 sections have already been spotted by Mary (@bocachicagal), along with BN2 and even BN2.1 sections, which may likely involve a Super Heavy – and/or Test Tank – for ground testing to pave the way for BN3’s launch.
Orbital Launch Site:
While vehicle hardware is being staged at the Production Site, the ever-changing skyline down Highway 4 at the Launch Site visually portrays SpaceX’s orbital aspirations.
A huge amount of work continues to occur next door to Starship’s current home, with the Orbital Launch Site (OLS) working on the installation of GSE (Ground Support Equipment) and the huge Launch Integration Tower.
The tower will be the tallest structure in the area when complete, with the base and opening section already constructed while additional sections are being fabricated ahead of rolling to the OLS for installation.
It has been speculated that any potential leap from SN15 to the orbital attempt would have added benefits of mitigating disruption to the OLS construction efforts.
Numerous pieces of the Super Heavy pad still need to be assembled in-situ, with the launch table currently at the production site, along with additional GSE that will be required to cater for the thirsty Super Heavy booster.
The Launch Tower will also sport a crane for mating Starship atop Super Heavy and eventually large mechanical arms that will “catch” the booster when it returns to the launch site.
Starbase, TX.
Powered by @Spaceport3D! pic.twitter.com/NZcJZZPl6J
— Erc X (@ErcXspace) May 2, 2021
The latter is not expected to occur during the first few flights, likely resulting in SpaceX undertaking the path it used during the first Falcon 9 booster landings, with a soft touchdown on water.
Raptor Supply:
A major bonus of SN15’s safe landing was the recovery of the three Raptors it flew with. They will provide priceless post-flight data on performance in tandem with the information beamed back to launch control via live telemetry.
However, it can’t be understated how valuable hands-on examination of the engines will be for the test program, along with the allowance for potentially reusing them on future flights.
Starship SN15 at sunset yesterday. @NASASpaceflight pic.twitter.com/ht3OXEY7jp
— Jack Beyer (@thejackbeyer) May 7, 2021
Regardless, SpaceX’s Starship program will require a huge supply of engines, not least the Super Heavy boosters, each of which will require a stock of 28 engines per booster.
Although production status at Hawthorne in California is unknown, test capability at SpaceX McGregor is being expanded.
SpaceX tests Raptors in two horizontal test bays while the converted tripod stand caters for vertical test firings. In addition, McGregor recently started construction of a new test stand next to the horizontal stand. In typical SpaceX fashion, this new dual-bay stand has been all but completed in a matter of weeks.
Via NSF’s Gary Blair in the L2 McGregor section, a local who flies past the test site at around 3,000 feet AGL, a Raptor has already been seen in one of the bays on the new stand, likely for fit checks.
The current horizontal stand has already seen at least two Vacuum optimized Raptors tested, which also shows how far in advance SpaceX has been moving to lay the path for taking Starship on orbital missions.
The only question is schedule planning, which can change almost by the day. However, with SN15 achieving the latest milestone, SpaceX’s “Test, Fly, Fail, Fix, Fly” approach is clearly working and continues to be fascinating to follow.
For live updates, follow NASASpaceFlight’s Twitter account and the NSF Starship Forum Sections.
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