SpaceX’s Starship development has caught the attention of many across the world, particularly after the spectacular flights of SN8 and SN9, both of which ticked multiple objectives for the vehicle and its radical design.
Overall, they were renowned successes, and created interest like I’ve never seen before in the spaceflight community. However, both vehicles failed on one crucial objective; landing.
But both instances have exposed failure points in the vehicle, something SpaceX have recognized and resolved. SN8 exposed an autogenous pressurization issue in the header tanks, now resolved by using helium to pressurize them. SN9 exposed a Raptor ignition flaw, which has now been resolved through redundancy mitigation in the landing burn.
The point being, existing failure points have now been resolved. At face value, if no more failure points crop up, there’s nothing that should stop SN10 from finishing the job SN8 and SN9 couldn’t quite achieve.
But rocketry is never that simple.
What’s SN10 been up to?
Starship SN10 took its place on Launch Pad A on January 29, alongside SN9 on Pad B, marking the first time we saw two Starships together at the launch site.
SN9 took flight four days later on February 2. In its aftermath all eyes were on SN10, and as usual with Boca Chica operations, its testing campaign was imminent already.
Unlike SN9, SN10 did not have its trio of Raptor engines installed prior to pad transport. Elon said this would happen after it completed its cryo test:
Cryoproof, then install engines
— Elon Musk (@elonmusk) January 29, 2021
But as ever with Starship operations, plans change constantly so during the first week of January, the three Raptors were installed before the cryo.
And before long, the testing campaign begun with a cryogenic proofing test (cryo test) whereby the vehicle was loaded with superchilled liquid nitrogen to verify structural integrity.
This was completed on February 8, just six days after SN9’s flight.
A couple of screenshots from Starship SN10’s cryoproofing. Looks like it went well based on previous examples. Waiting for the frost to go back down and road opening, etc.
— Chris B – NSF (@NASASpaceflight) February 8, 2021
Following the cryo test, a static fire was expected as usual, where the vehicle is held down but all three Raptor engines are ignited for a few seconds qualifying a multitude of hardware on the prototype, ready for flight.
Static fire occurred on February 23.
And we have a static fire 🔥
Looked to be a good duration; rapid depress/detank after shutdown which hasn’t been a great sign in the past (sign of an abort) – but we’ll see what happens.
— Leo 🚀 (@TerminalCount) February 23, 2021
The static fire appeared to be a good duration, but as I outline, the rapid depressurization venting after shutdown hasn’t been a good sign in past static fires.
This vent releases all pressure from the liquid oxygen and liquid methane tanks, and allows for detanking to occur whereby the propellants can be withdrawn or boiled-off from the tanks. This naturally happens at the conclusion of a test, in order to safe the vehicle and allow work to continue at the pad.
But, to see it directly after the shutdown of engines usually signals an abort has occurred. The vehicle’s computer has detected an anomaly, and it seeks to safe the vehicle as soon as possible.
Usually, we have seen them withhold from detanking until a few minutes after the static fire, likely for data collection post-ignition. This is without computer intervention in the form of an abort.
Elon confirmed this shortly after:
One of the engines is suspect, so we’re swapping it out
— Elon Musk (@elonmusk) February 24, 2021
As of present, a new replacement Raptor has been delivered to the launch site and will be swapped out with the anomalous one.
In keeping with past experiences, another static fire is highly likely.
This should hopefully be completed in the coming days, potentially more than a week.
The flight of SN10
In the aftermath of the first static fire, a flight depends on a successful second one and favorable weather.
At present, there are launch Temporary Flight Restrictions (TFRs) set for Thursday, Friday and Saturday (February 25, 26, 27), combined with road closures on Thursday, Friday, Monday and Tuesday (February 25, 26, March 1, 2).
As ever with these dates, they can change very easily. The bottom line is that a more solid estimation can be given once there is a nominal static fire, which we’re yet to have.
In regards to Federal Aviation Administration (FAA) approval for launch, there are no hurdles to jump.
Update on SpaceX’s Starship program from the FAA just in: “The FAA closed the investigation of the Feb. 2 SpaceX Starship SN9 prototype mishap today, clearing the way for the SN10 test flight pending FAA approval of license updates.” (1/4)
— Jackie Wattles (@jackiewattles) February 19, 2021
Go for launch: The FAA has granted SpaceX a launch license modification for Starship SN10. So we could see a flight this week as Elon said, pending successful static fire, which could come as early as today.
— Christian Davenport (@wapodavenport) February 22, 2021
How will SN10 make a success out of SN9’s failure?
As discussed in my other article, SN9 failed to land due to an anomalous Raptor failing to ignite on the landing burn. More detail on mitigation can be found there.
Since, NASASpaceFlight understand that incident was down to an “apparent ignitor issue” in the engine. This is unconfirmed, but the best indicator we have of the incident as there has been no official news.
According to Elon himself, these are the chances that SN10 will land:
Success on landing probability is ~60% this time
— Elon Musk (@elonmusk) February 14, 2021
Best of luck SN10, as always, we will be watching whatever the outcome.