Starship SN15 prepares for flight following major NASA vindication

by Chris Bergin

Starship SN15 is expected to undergo a Static Fire test as early as this week to clear the path for a test flight as SpaceX’s rapidly reusable interplanetary launch and landing system gained a massive sign of NASA approval – and a ton of government cash to boot.

SpaceX was the sole winner of NASA’s initial Human Landing System (HLS) award worth in total more than $2.9 billion, meaning the human return to the Moon’s surface will be via Starship.

Starship SN15:

Classed as the next evolution of the prototype Starships, SN15 will aim to go one step further than its predecessors.

Although SN8 through SN11 have all successfully launched to their planned apogee, flipped, and conducted a stable “bellyflop” return to the landing site, only SN10 managed to successfully land upright on the pad before then exploding due to the hard landing.

SN11 exploded during the Raptor relight procedure that initiates the flip maneuver, resulting in the vehicle falling to the ground in pieces, albeit under the cloak of thick fog. One of the known modifications on SN15 is to the engines, which should aid the chances of success.

With the vehicle arriving at the launch site a week ago, SN15 underwent proof testing events before Raptor installation, allowing Thrust Rams to test the Thrust Puck, one of the other modifications that will debut with SN15.

During this process, SN15 was filled with ambient gaseous nitrogen before the cryogenic testing with liquid nitrogen completed proof testing, including the Header Tanks that play a vital role in the landing sequence.

The three Raptors (SN54, SN61, and SN66) – sporting the green nozzles that have been observed during testing at SpaceX McGregor – then rolled to the launch site for installation. As previously noted by Elon Musk, all three are upgraded engines.

Installation tasks began ahead of the weekend, with the goal of readiness for the opening Static Fire test window on Monday, April 19. However, that soon slipped day on day during the week.

Once the Static Fire test has been completed, SpaceX will conduct a data review. On several previous occasions, the data has called for an engine swap. As such, a clean data review ahead of the Launch Readiness Review (LRR) would be a step forward for the Raptors.

SN15’s flight is still waiting for the final green light from a documentation standpoint, which will come from the FAA. As of Sunday, the FAA classed that approval as “pending.”

Additional factors in play this week for launch operations will be local weather conditions.

Key details about SN15’s flight have not yet been revealed. It is likely to repeat the 10 km hop and utilize the redundancy of relighting three Raptors during the landing flip – before deselecting the engine with the least lever arm, should all three fire up – and then attempt to land on two engines to cover a potential loss of thrust as seen on SN10.

Starship SN10 did land successfully. However, it hit the landing pad concrete at an unacceptable velocity, resulting in damage to the vehicle’s aft that ultimately led to an explosion minutes later.

The above section will be updated during key milestones to SN15’s flight.

Future Vehicles:

Ultimately, SpaceX has one eye on Starship SN20, which is the first of the “Orbital Class” prototypes that will sport a full array of TPS (Thermal Protection System) tiles on the windward side of the vehicle.

SpaceX has been working on large TPS application for some time – picture via Mary (@bocachicagal)

SN15, as with previous prototypes, has received an increased amount of tiles, allowing SpaceX to test how the TPS performs under the stress of cryoloading the vehicle, along with launch and landing.

SpaceX is fully aware that it requires numerous flights to fine-tune their understanding of a highly unique flight profile. As such, they aren’t betting the house on SN15 completing all the milestones to the point they could move right along to SN20.

In fact, even if SN15’s flight is a roaring success, repeating the achievements is key. That was also the process seen during the 150-meter hops of SN5 and SN6, with the former providing a successful test before the latter repeated – and improved – on the hop objective.

Those successes ultimately moved SpaceX forward from their initial plan to conduct numerous 150-meter hops before SN8’s high altitude test.

As such, SN16 will be prepared for both possible outcomes of SN15’s flight, either refining issues found during its predecessor’s flight or aiming to repeat and potentially improve on the latter.

SN16 is currently being stacked in the Mid Bay, where it will wait its turn in the High Bay for nosecone mate operations.

One constant at SpaceX’s Starbase (Boca Chica) is the production cadence, with the aforementioned SN20 already being constructed.

The Forward Dome of the vehicle is currently being prepared, with the likelihood of additional sections – including for vehicles SN21 and SN22 – already being worked on behind the doors of the Production Tents.

But as part of the drive to orbit, SpaceX requires the Super Heavy booster.

Although BN1 wasn’t set to fly, it was expected to at least roll to the suborbital launch site for transportation and proof testing objectives. Instead, SpaceX decided to scrap it, with sections removed and sent to the nearby scrapyard.

While BN1 still provided useful pathfinder objectives, BN2 will be stacked with its tanks (LOX and CH4) in reverse order – explaining why BN1 did not roll to the launch site given the significance of that change to the design.

BN2 stacking in the High Bay will also take advantage of the recently installed bridge crane, which could expedite the build-up of the booster.

Meanwhile, BN3 – which could be the booster that launched with Starship SN20, per the initial plans – has already been spotted by Mary (@bocachicagal). This includes an Aft Tank Ring Section in addition to the domes.

Grid Fins that will aid Super Heavy’s return, as enjoyed by Falcon 9 boosters, were also spotted in recent days.

The mated Super Heavy and Starship stacks will launch from the Orbital Launch Site (OLS), next door to the suborbital site.

A huge amount of work continues to take place in this area, with the addition of GSE (Ground Support Equipment) tanks – some of which are, in typical SpaceX fashion, custom-built from Starship steel rings.

While the launch table remains at the Production Site, waiting to be integrated with the since-constructed launch mount, work is now taking place, at pace, on the Integration Tower.

This huge structure will become the tallest building in the region, allowing numerous operations from lifting Starships atop Super Heavy boosters via a crane to worker access to the stacked vehicle to mating electrical and fluid lines.

As Elon continues to note, it is currently likely to include large mechanical arms that will catch a returning Super Heavy booster. This technique will remove the need for landing legs on the Super Heavy and, if successful, would also greatly reduce turnaround time between launches of Super Heavy boosters as the arms would be able to place the rocket immediately back on the launchpad.

Completion of this pad, to the point it can be used as an operational site, is expected within the next few months as SpaceX pushes towards the milestone of reaching orbit as early as this summer.

HLS Starship:

Just a few years after SpaceX Boca Chica was merely a tent near the beach, Starship’s incredible production and testing cadence has paid off with a massive NASA contract now in the bag.

Lunar Starship – Render by Mack Crawford for NSF/L2

Starship is ultimately aimed at launching cargo and crew to the surface of Mars, allowing for a permanent base to be built and achieving Elon Musk’s goal of making human life multi-planetary.

Despite the Starship Launch System being privately funded, including via milestone payments for the #DearMoon mission, SpaceX’s business model likely includes additional internal funding via profits made in other areas of its business, such as Starlink and potentially already-secured commercial launch contracts.

Winning government contracts not only provides financial strength to the development outlay, but also provides validity to the company’s approach.

The HLS team has been seen visiting Boca Chica on numerous occasions with several NASA astronauts, allowing them to gain insight into Starship operations.

Now, those astronauts can look forward to returning to the Moon on the lunar version of Starship, following the $2.89bn “Option A” contract being awarded to SpaceX, with Blue Origin and the National Team along with Dynetics missing out.

SpaceX Lunar Starship – via NASA

While the single provider award came as a surprise, the rationale is apparent. Both Dynetics and the National Team suffered from major requirements shortcomings, while Starship caters to every need at a lower price.

A mock-up of the Lunar Starship nosecone has been on display at the Production Site for some months, with the interior outfitting allowing HLS members to gain real-life information.

The HLS Starship Mock-up -via Mary (@bocachicagal).

The first flight of the Lunar Starship will be on an uncrewed demonstration flight as part of NASA’s Artemis program. The actual date of the first crewed Lunar landing is yet to be decided, with the hope of 2024 being less likely in recent months due to funding issues but not entirely impossible given Starship’s selection.

It is expected that Artemis 3 will now be a shakeout mission to the Gateway that could include the uncrewed Lunar Starship demonstration test. This would cater to a full-up lunar landing mission during Artemis 4.

Several in-depth reviews of the NASA contract award will be published in the coming days.

For live updates, follow NASASpaceFlight’s Twitter account and the NSF Starship Forum Sections.

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