After a build-up of excitement around a potential start-of-year flight for SpaceX Starship prototype SN9, things has slowed down somewhat – but the vehicle may now be on the brink of making its 12.5 km ascent to altitude and an attempt to land successfully after an unpowered “skydive” back towards Earth.
As I noted in my January 10th Space Sunday report, SpaceX had managed to accelerate the processing of SN9 in comparison to SN8 to a point where the majority of pre-flight checks for the vehicle – including a static fire test of the engines on January 6th – had been completed in just a 2-week period following its delivery to the launch stand on December 22nd, compared to 2 months taken for prototype SN8 to reach the same point.
However, as I noted at the time, that static fire test was far shorter than had been expected – just 2 second in length, signifying a possible issue. This appeared to be confirmed when SpaceX attempted further engine tests between January 8th and January 12th, of of which had to be scrubbed for various reasons (including weather), before a further test was made on Wednesday, January 13th – and things took an unexpected turn: after the first brief test, two further tests took place within a 2-hour period for all three tests.
The three firings were apparently “test starts” of the three Raptor motors, rather than a full pre-flight static fire test of all three simultaneously. Following them, and a successful de-tanking of excess fuel, inspections of the motors revealed that two needed slight repairs, causing the company to swap them out for other units.
As part of streamlining starship operations, SpaceX have refined the processes related to engine swap-outs to a point where they can effectively be achieved within days rather than weeks, depending on the availability of replacement motor units – the actual physical removal of an engine can be completed in hours, as can the installation of a replacement. In this case, the work was done over a couple of days, the engines requiring replacement being removed from the vehicle and shipped out of Boca Chica before the replacements were delivered and installed, clearing the way for a final engine test.
This took place on Friday, January 22nd, when all three engines were ignited for several seconds before shutting down.
Outside of SN9, it appears work at Boca Chica has commenced on starship prototypes SN17 and SN18, and on the second Super Heavy booster prototype. Also, in my January 10th Space Sunday update, I noted that work had been discontinued on starship prototypes SN12 through SN14. Work has now commenced in dismantling those parts of SN12 that had been fabricated. This is likely due to the fact that SpaceX are iterating the design and construction of the prototypes so fast, SN12 had become effectively obsolete due to the materials used.
The rapid rate of iteration is also reflected in the move of a new fuel tank section – SN7.2 -, which has been moved to a test stand where it will be pressurised to destruction in a similar manner to the SN7 and SN7.1, each of which also saw iterations in the basic tank design. SN7.2 in particular is built using 3 mm aluminium rather that the current 4 mm material in an attempt to reduce the overall “dry” mass of the vehicle.
In 2020, Musk raised the idea of launching starship / Super Heavy vehicle from sea platforms, suggesting this could be used for vehicles intended to reach orbit or in passenger-carrying sub-orbital transcontinental flights.. While passenger carrying point-to-point will not happen (for reasons I will explain at some point), evidence has emerged that SpaceX are planning to make sea launches a thing, and is in the process of converting two former offshore drilling platforms for use as floating launch platforms.
Aerospace Photographer Jack Beyer was the first to bring the news to the public eye after exploring the port of Brownsville, Texas, not far from the SpaceX facilities at Boca Chica whilst waiting for the SN9 static fire tests to resume. In particular, he spotted an oil platform apparently called Deimos (“dread”) undergoing extensive refit work. Not long after, a image captured over the port of Galveston, Texas, and dated January 13th revealed another rig with the name Phobos (“fear”), and which was later moved to Pascagoula, Mississippi, between January 17th and 22nd.
Phobos and Deimos are, of course, the names given to the captured moons of Mars, and the discovery of the two rigs sparked speculation that the platforms had been purchased by SpaceX.
Michael Baylor from NASAspaceflight.com started digging into things using further images captured by Jack Beyer, and discovered that the two rigs in question were originally owned by the world’s largest offshore drilling / well drilling company: UK-registered and Texas-based Valaris plc (formerly ENSCO-Rowan).
Originally constructed in Singapore in 2008, the two rigs were originally called ENSCO 8500 (later Valaris 8500 and now Deimos), and ENSCO 8501 (later Valaris 8501 and now Phobos). However, following the company declaring bankruptcy, the company offered the platforms for sale and US 3.5 million apiece. The purchaser was company called Lone Star Mineral Development LLC, which had only formed in June 2020. Further digging revealed that one of the principals for Lone Star Mineral Development is none other than SpaceX Chief Financial Officer (CFO), who is also the head of the company’s Strategic Acquisitions Group, Bret Johnsen.
Both platforms are classified as “semi-submersible”, meaning they float on large pontoons that can be filled with water ballast that both settles them in the water to stabilise them while dynamic positioning water thrusters hold them in a precise location, making them an ideal launch platform, as does their deck loading of around 8,000 tonnes, means that are more than capable of supporting a Super Heavy / starship combination and their fuel loads.
The work to convert the two platforms to support fuelling, payload integration, launch, and landing operations is extensive. As such neither is likely to be ready for use in 2021. However, once operational, they will effectively double the number of Super Heavy / starship launch facilities – SpaceX is currently building the first Super Heavy platform at Boca Chica, and have plans for a second. Multiple launch facilities will be essential in the future if SpaceX is to start to build towards the planned number of launches for the system..
Continue reading “Space Sunday: rockets, water and spaceplanes”
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