SpaceX’s Starship Prototype test program took a giant leap forward on Wednesday, as SN8 conducted a 12.5 Kilometer test flight – and a landing attempt – at the company’s facilities in Boca Chica, Texas.
Successfully landing Starship SN8 had but a slim chance of being achieved. However, data from the flight – and the major steps forward with an ascent, controlled descent and flip – will have provided vital data to be fed into a fleet of follow-on tests, starting with the next Starship, SN9, which is all-but ready to roll once SN8 has vacated the launch mount.
(Lead Image via Jack Beyer)
Quick Background:
Starship SN8 marked the new phase of testing for SpaceX’s fully and rapidly reusable, interplanetary launch system.
That goal is in itself one of the main reasons there’s an incredible level of interest in Starship’s development, with the project growing from Elon Musk’s initial 2016 presentation to the IAC in Mexico, numerous iterations and name changes, through to the physical construction and flight of test vehicles.
*Click here for an 8,000 word feature article on Starship’s history ahead of SN8*
Rising from the ground in just a few years, SpaceX now has a Production Facility and a Launch Site in South Texas, a speedy build-up that is now matched by its vehicle assembly cadence.
SpaceX Boca Chica Production Facility – via Mary (@bocachicagal)
Firstly, Starhopper – which still stands tall at the launch site as a multipurpose instrumentation rig, close circuit TV stand, public announcement system, and workers picnic table protective cover – leaped into the air to validate numerous systems involving the tankage and engine systems, paved the way for Starship’s test program.
This test was conducted in August of last year, showing how fast SpaceX has progressed in a short period of time.
The brave 150-meter hop of the test vehicle, dubbed a flying water tower, will always be looked back upon as a significant step forward, along with providing SpaceX some cash via the milestone payment plan from Japanese billionaire Yusaku Maezawa, who is set to fly around the Moon on a future Starship.
Challenges with any test program can be expected. However, coupled with SpaceX’s allowance for failures as part of its “Test, Fly, Fail, Fix” mantra, such setbacks have not proven to be critical in Starship’s advances.
With the early SN Starships showing an unhealthy desire to be reborn as future Cybertrucks, the most dramatic failure proved to be no fault of the vehicle. Starship SN4’s RUD (Rapid Unscheduled Disassembly) came after being on track to be ready to complete the first hop test. A Ground Support Equipment (GSE) issue led to its demise as it exploded after a Static Fire test.
Importantly, each failure provided a goldmine of data that has been fed into the manufacture and processing of future Starships. This continues to be an evolving design from a materials standpoint, with SN8 still including some of the 301 steel alloy whilst mostly being built from a variant of the 304L alloy. SpaceX intends to employ its own alloy recipe into Starships further into the future.
For the interim, SpaceX is using an evolved test plan to put their vehicles through their paces. This began with the successful hops of SN5 and SN6.
While SN5’s hop went to plan, the improvement with SN6’s test removed the need to continue to conduct 150m hops with these near-twins. As such, they both now reside at the Production Facility without any obvious future.
After some Test Tanks under the SN7 designation provided more data, SN8 was then produced for the next big leap forward – as a full-scale Starship with a nosecone, aero surfaces, and three Raptors in the aft.
SN8’s Test Flight:
By SpaceX Boca Chica standards, the path to this test flight has been “slowed” by varying factors, mostly relating to numerous first-time processing events, ranging from the first installation of a nosecone on a full-scale Starship through to several prop loading and Static Fire tests – the latter including the utilization of the LOX Header Tank located in the nosecone.
The first time all three Raptor engines were lit up was a company first. Raptor engines are always fired as individual units during their long-duration tests at SpaceX’s McGregor test facility up the road in central Texas.
Some challenges were observed, resulting in two engine swaps through the SN8 pre-launch test campaign, meaning the three Raptors that flew with this Starship were SN30 – the only engine that has remained with Starship SN8 since the engines were first installed – along with SN36 (taking over from SN39), and SN42 (which took over from SN32).
Raptor SN42 installed into Starship SN8 – via Mary (@bocachicagal)
SpaceX had been looking for an opportunity to conduct one final Static Fire test. However, this was deemed to be only if the opportunity in the schedule arose, as opposed to any specific requirement ahead of the flight.
The option to conduct a final Wet Dress Rehearsal (WDR) was taken on Monday, which proceeded without issue.
I caught Starship SN8 being rather noisy prior to road closure. The road has closed so join us for what is expected to be a WDR.@NASASpaceflighthttps://t.co/8zOBUcpIgO pic.twitter.com/yvcodqzccI
— Mary (@BocaChicaGal) December 7, 2020
The test flight’s target date did slip from last week to this week, initially relating to weather conditions. Approval to conduct the test was already provided last week, with documentation showing the 15 KM altitude target and a local exclusion zone.
The test was originally targeting 20 KM, before being reduced to 15 KM and most recently to 12.5 KM. The latest altitude reduction was understood to be related to high altitude winds as the vehicle translates from its powered ascent into the bellyflop return utilizing its aero surfaces.
That remains the key objective, based on SN8’s trio of Raptors successfully loft the vehicle to its target altitude.
With the launch scrubbed at T-1 seconds on Tuesday, the second attempt took place on Wednesday. With a hold called during the first countdown attempt, the second resulted in the launch.
For the first time during Starship testing, the aero surfaces came into play, as SN8 glided/descended – or, as many like to word it, belly-flopped back toward terra firma.
This phase of the test was always a major data point for SpaceX, allowing them to recreate what they had already evaluated in a wind tunnel in the more challenging regime of real life.
Stable, controlled descent with body flaps would be great. Transferring propellant feed from main to header tanks & relight would be a major win.
— Elon Musk (@elonmusk) October 31, 2020
SN8 remained under great control during the return, before the next major milestone involving a Raptor relight to push the vehicle vertical via the use of the Thrust Vector Control (TVC) system. As SN8 swung her aft toward the ground, the TVC pointed the nozzles and direction of thrust to aim the aft at the landing pad.
The subsequent “wobbly landing” – caused by a loss of pressure in the fuel Header Tank – is something that can be refined via the data gathered from SN8’s attempt.
“Understanding exactly how the body flaps control pitch, yaw & roll during descent, such that the ship is positioned well to relight, flip & land, would be a big win,” added Elon in subsequent Twitter replies.
That certainly went to plan, with only the final few seconds suffering an issue and the loss of the vehicle, but only after several major objectives were achieved – allowing for an acceleration of testing to higher altitudes.
Exactly! Woohoo!!
— Elon Musk (@elonmusk) December 10, 2020
Future Starships:
Thanks to the incredible production cadence at SpaceX Boca Chica – and thanks to SN8 avoiding a crash into the propellant tank farm – the next Starship test could be just a matter of weeks away.
Starship SN9 is fully assembled and ready to roll down Highway 4.
Starship SN9 in the High Bay – via Mary (@bocachicagal)
Unlike SN8, SN9 received its nosecone inside the High Bay. This will allow for an expedited pad flow, potentially only involving one or two Static Fire tests before being readied for her own test flight.
While that pad flow is taking place, additional Starships are lining up for their own big day.
SN10 and SN11 are inside the Mid Bay, while Starship sections all the way through to SN16 have been spotted around the Production Site.
This is in tandem with the sections for the first Super Heavy prototype rocket, which has already begun the opening phases of stacking inside the High Bay next to SN9.
This prototype booster will take up residence at the Orbital Launch Mount, which is being constructed next to the facility that hosts the Starship vehicles.
The current status of SpaceX's Starship & Superheavy prototypes. 5th December pic.twitter.com/J4alSB33Rr
— Brendan (@_brendan_lewis) December 5, 2020
Elon Musk has before cited this production pace as a key element to moving through Starship test flight objectives, allowing for a launch cadence that caters for expected issues during the test flights.
This ability to test launch without a critical delay caused by any potential failure, all while adding refinements to the tests as they learn more about how the vehicle performs in the air, is likely to place Starship in a very strong position for achieving orbital flight next year.
Photos via Mary (@bocachicagal)
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