SN6 begins test campaign as future Starships hatch plans for SpaceX’s next leap

by Chris Bergin

Following the successful test of Starship SN5 during its 150-meter hop just a week ago, the next Starship (SN6) is preparing to repeat the test in the coming days. With a potential tag-team – or hop-team – role for SN5 and SN6, a roadmap is starting to form ahead of the more ambitious tests that will involve Starships SN8 and SN9 – both of which are already under various stages of construction at SpaceX Boca Chica.

With the incredible build and test cadence continuing at SpaceX’s facility in South Texas, a “hot-swap” in the Mid Bay was required after SN5 rolled back from the launch site, following what was the first successful hop of a Starship test vehicle.

With SN6 already assembled in the Mid Bay and waiting patiently for her turn at testing, the two prototypes swapped places, allowing SN5 to take SN6’s slot in the bay, while the latter rolled to the vacated test mount at the launch site.

Starship SN6 – a near-twin to SN5 – is currently pushing through a pre-hop test sequence that includes proof-testing ahead of a Static Fire test, laying the path toward its own 150-meter hop.

SpaceX CEO and Chief Designer Elon Musk recently noted there will be numerous hops to refine the launch sequence, providing useful data ahead of the next major milestones that will see a future Starship launch as high as 20 kilometers.

This could result in SN5 and SN6 tag-teaming over the coming weeks, each replaying their 150-meter hops under the power of a single Raptor engine.

First, SN6 is required to pass numerous tests ahead of the hop, including proof/cryo testing, milestones that occurred on Sunday with the loading of LN2 (Liquid Nitrogen).

Providing all goes well with those tests, the hydraulic rams – placed in the launch mount to impart forces on the aft of the vehicle during pressurization tests – will be removed and a Raptor engine (likely SN29) will be installed on SN6. This will allow the Static Fire test to take place, which will provide a green light to proceed toward the 150-meter hop.

Following the test, SN6 will either be placed back on the launch mount for a second hop or rolled back to the Mid Bay to tap SN5 back into the game for her second hop.

Likely to take place during the hop series, a Test Tank, called SN7.1, will make a trip to the launch site for a test of its own. While both SN5 and SN6 are made from 301 Stainless Steel, SN7.1 is made from 304L (or at least a variant of this alloy). 304L is what all near-term future Starships will be made from before SpaceX employs its under-development proprietary alloy.

Data from SN7.1 will be fed into the data set that will guide pressure allowances on Starship SN8, which has already begun final assembly inside the Mid Bay next to its new neighbor, SN5.

With SN8 also made from 304L, the vehicle is set to provide the next leap forward – or upwards – for SpaceX’s Starship Launch System (SLS – not the orange one).

SN8 is expected to gain the nosecone, made from a five ring barrel section and the fairing dome, along with aerodynamic control surfaces, pointing towards a much greater leap compared to the tests with her younger sisters.  While such a completed nosecone has been observed inside the Windbreak, it has not been confirmed that this is the nosecone section that will be installed on SN8.

SN8 Aft Section Flipped, next to SN9 dome – via Mary (@bocachicagal) for NSF

Numerous nosecones, to the point of it becoming amusing, can be seen waiting their turn for potentially becoming flight-worthy. Ultimately, the nosecones which include a header tank are believed to be the most likely to fly.

SN8’s aft section is also expected to gain fins, with aft fins already seen on site, along with additional hardware recently arriving via new deliveries over the past few days. Most notably, SN8 will fly with three Raptor engines.

While SN8 presses onwards to become the first full-stack Starship, SN9 has been seen in public for the first time, with a Common Dome section rolled out of one of the Big Tents at the Production Site.

Although it is early days for SN9, this sighting intimates that there are likely parts – namely bulkheads – for several other Starships under construction inside the Big Tents, given the lead time and Elon Musk’s note that this is one of the hardest parts of Starship to construct.

Moving past Starship, preparations for the huge Super Heavy booster are in full swing at both the Production Site and the Launch Site.

Continuing to rise above Level 3, the new High Bay is being built at pace. Construction of the High Bay only began a month ago and has since risen to become the tallest building at SpaceX Boca Chica.

This 81-meter tall facility will host the stacking of Super Heavy sections before the vehicle is then rolled to the launch site for mating with the Starship vehicle.

Notably, work on the Super Heavy launch site has picked up considerably over recent days.

Located next door to the Starship test site that currently hosts SN6 and permanent resident Starhopper, the Super Heavy pad was a placeholder area of SpaceX Boca Chica, with only its land area laid out by Earthmovers via ground preparations. However, it came back to life via numerous borehole drilling operations, as foundations for what is envisioned to be a huge launch tower were laid.

In recent days, the shape of foundations for a new structure has been observed, although it is not clear if this will become the launch tower structure, a water tower for Super Heavy’s Sound Suppression System – or something completely different.

Now classed as the “Orbital Launch Pad”, rebar cages have been placed around the immediate construction area, akin to how the Tripod Test Stand at SpaceX’s McGregor test site was constructed (albeit by original tenants, Beal Aerospace).

SpaceX’s official renderings of Super Heavy launching from Boca Chica place focus mostly on a HIF (Horizontal Integration Facility) and the huge service tower. However, such footage, however official, should always be deemed notional, not least when portraying an ever-refining launch system.

What can be confidently assumed is SpaceX is preparing the facility groundwork for the first assembly and testing of Super Heavy by 2021.

Test programs and new vehicles will always stretch schedules. However, there remains the distinct possibility SpaceX could launch their first Super Heavy rocket before the Space Launch System (SLS – the orange one) is due to conduct her maiden launch at the end of next year.

(Lead photo by Mary (@BocaChicaGal) for NSF)

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