Starship SN15 is set to fly on Tuesday, testing upgrades that SpaceX hopes will result in a smooth touchdown on the Boca Chica landing pad. The test will take place amid ongoing groundwork for the push to orbit is taking place both at the Orbital Launch Site and elsewhere in Texas as a new dual-bay Raptor test stand nears completion.
Since arriving at the Suborbital Launch Site, SN15 has undergone several “risk reduction” tests ahead of firing up her trio of Raptors.
That included the usual routine of proof testing the vehicle, filling and pressurizing the tanks with ambient, gaseous nitrogen before proceeding with cryogenic testing with liquid nitrogen.
The vehicle was also loaded with Liquid Oxygen before a LOX Dump test, aimed at improvements relating to safing the vehicle ahead of and after the flight, was completed.
SpaceX then conducted a three engine Static Fire test, firing up the SN54, SN61, and SN66 Raptors, which was followed by a quick look data review. Occasionally, such reviews have found issues with one of the engines, requiring a swap out and repeat of the test in the following days. However, this time the trio performed without issue.
The potential of a recycle later in the day remained on the cards, given SpaceX likes to test the engine’s use of propellant from the Header Tanks.
These small tanks are located at the top of the nosecone (LOX) and the middle of the vehicle (CH4 – Liquid Methane) and supply the engines for the flip and landing burn.
It was yet to be confirmed if that concluded the test requirements, with another Static Fire noticed posted to local residents.
Then, with roadblocks in place, SN15 headed into another test cycle resulting in a planned single-engine Static Fire test.
STATIC FIRE 2. Starship SN15 fires up a second time ahead of a test flight in the coming days.
Latest Status Article:https://t.co/t2uFhIa1FQ
— Chris B – NSF (@NASASpaceflight) April 27, 2021
All this testing is aimed at conducting another smooth flight and an attempt to nail a smooth landing. That attempt was to take place on Friday.
However, a scrub was called, resulting in the launch moving to early next week. While the weather was the main watch item on the due, the decision to call off the attempt was due to a flight software issue. Confirmation was then gained for an attempt on Tuesday.
All eyes will be on that key phase of the flight, with Starship having already proven and repeated numerous major milestones while only landing in one piece during the SN10 test. However, that was a hard landing, resulting in the vehicle exploding minutes later.
Moving on from those initial series of test with SN8 through SN11, SN15 is the first vehicle to sport improvements ranging from the Thrust Puck to her avionics, and, importantly, the Raptor engines.
Other improvements have not been revealed, although may include the Header Tank system, which, in total, would form a mitigation path to the issues suffered by previous Starship prototypes.
Regardless, should SN15 suffer issues, SN16 is already being stacked in the Mid Bay. However, if SN15 nails the landing, the path forward becomes less clear, albeit even more exciting.
As seen after the successful 150-meter hops of SN5 and SN6, SpaceX’s original plan to conduct a tag-team approach of repeating tests with these two vehicles was canceled. Instead, the program pushed forward to SN8 and the first high altitude test.
Should SN15 complete all the required high altitude test objectives, SpaceX may repeat the test or push to a higher altitude. Elon Musk could even opt to switch to the involvement of Super Heavy, which may involve a booster-only flight, or the previously reported BN3 and SN20 orbital flight.
Drive To Orbit:
Starship’s early orbital ambitions have been previously mentioned in actual SpaceX documentation, as reported by this site and confirmed by the “that’s the goal” tweet from Elon.
While the documentation noted “by July 1”, taking the usual overly optimistic timeline that has often been associated with Starship milestone targets, the potential of an orbital flight in the summer remains an amazing prospect.
Numerous pieces of the puzzle need to fall into place. However, all those pieces are currently being worked.
Firstly, the requirement of covering the entire windward side of Starship in Thermal Protection System (TPS) tiles has seen incremental increases in the TPS patches seen on the flight prototypes, with SN11 hosting a record number of tiles.
Over at the Production Site, Mary (@bocachicagal) has photographed sections completely covered in tiles.
Secondly, the “blunt nosecone”, which was then surrounded by a test cage, has been rolled out to the Launch Site, allowing for stress testing.
The goal will be to use the test rig to impart forces on the nosecone while pressurized. This will mimic how the nosecone performs under the aerodynamic stresses of heading uphill on an orbital mission.
Thirdly, Super Heavy and its launch site.
The Orbital Launch Site is a hive of activity, with work ranging from the installation of large GSE (Ground Support Equipment) tanks to continued work on the launch mount and launch and integration tower.
The latter has now started to rise into the air next to the mount, which is yet to receive its launch table.
When finished, the tower will be the tallest structure in the region, at nearly 152 meters — towering over the 120 meter tall, fully integrated Starship/Super Heavy stack. The Tower will eventually host a crane and, as crazy as it initially sounded when Elon revealed it, arms designed to catch the returning booster.
SpaceX often conducts testing before all of the infrastructures is in final configuration, meaning the launch mount and table, along with the tower structure, could be enough for the initial test launch.
Elon on the "Holy Grail" of *rapid* reusability, including more comments on the Super Heavy booster catching launch tower (and goal of Starship being caught) allowing for a capability to fly vehicles several times a day. https://t.co/W1cQNy5n0A pic.twitter.com/63z5XiwCry
— Chris B – NSF (@NASASpaceflight) April 22, 2021
While the BN1 Super Heavy prototype was only a pathfinder, SpaceX opted to scrap it before taking it to the Suborbital Launch Site for transportation and prop load testing. BN1 has since been cut into sections and sent to the scrap yard.
With Super Heavy now set to be stacked with the LOX and CH4 tanks in the reverse order to BN1’s configuration, SpaceX appears to be potentially creating a Test Tank version of the Super Heavy, with BN2 and BN2.1 sections spotted by Mary (@bocachicagal).
While it is not yet clear what the plan is for BN2 and BN2.1, they will pave the way for the first fully stacked flight Super Heavy, BN3.
BN3 has already been seen in sections at the Production Site and is likely to begin stacking in the High Bay in the very near future.
The current plan is to use this booster to fly Starship SN20 – already in production – on the orbital mission, although Starship milestone planning is constantly under review per vehicle assignments.
Questions also remain on how many Raptors BN3 will require to conduct the orbital mission. The full suite of 28 Raptors won’t be required and would not be desirable.
Elon has previously noted the Super Heavy test launch will use fewer engines as a mitigation against the likelihood a test mission would result in the loss of the vehicle. The Raptors are the most expensive element of the vehicles.
Regardless, SpaceX Starbase (Boca Chica) will have a great demand for Raptor stock this year. Production of the engines is understood to be close to or above the SN100 range. However, they have to complete test firings at the McGregor test site before they are sent on the “RaptorVan” down to the Production Site.
Raptor testing capacity has grown over recent years, with the addition of numerous test stands, including the conversion of the original stalwart Falcon 9 tripod stand, which now hosts vertical Raptor testing.
Elon Musk has previously noted that testing Raptor on vertical stands provides additional benefits.
Raptor engines – including the first two Raptor Vac (RVac) units – also undergo testing in two horizontal bays, located in an area of McGregor that will soon have another Raptor test stand as a neighbor.
The new Raptor stand has an underground diverter, and each of the vertical test bays will be available for testing both sea-level and vacuum-optimized Raptors. It is nearing completion at pace.
From being a bare patch of grass just a few months ago, NSF’s Gary Blair in the L2 McGregor section – a local who flies past the test site at around 3,000 feet AGL – photographs show the final preparations on the new stand includes the installation of the large pieces of the flame diverter into what is a deep flame trench.
With this increased test capacity, SpaceX will be able to run numerous numbers of Raptors through McGregor each week, catering to the demands of Super Heavy and Starship.
Notably, SpaceX’s Modus Operandi is to return their vehicles, with Starship being a rapidly – and fully – reusable launch system. As such, Super Heavy and Starship will be aiming to return their Raptors for additional flights.
Grab some cool gear along with the ability to support our content: https://shop.nasaspaceflight.com/