Starship SN8 | 12.5-Kilometer Hop | Post Launch Review

Lift Off Time
December 09, 2020 – 22:45 UTC | 16:45 CST
Mission Name
12.5km flight
Launch Provider
(What rocket company launched it?)
SpaceX
Customer
(Who paid for this?)
SpaceX
Rocket
Starship SN8
Launch Location
Boca Chica Launch Site, Boca Chica, Texas
Payload mass
n/a
Where did the satellite(s) go?
n/a
Did they attempt to recover the first stage?
Yes, unsuccessfully
Where did the first stage land?
The first stage made a hard landing on the landing pad in Boca Chica, Texas, and was destroyed.
Did they be attempting to recover the fairings?
n/a
Were these fairings new?
n/a
How did the weather look?
The weather was acceptable for the launch
This was the:
  • 1st flight of Starship SN8
  • 1st high-altitude flight of a Starship prototype
  • 3rd flight of a Starship prototype
  • 1st flight with a nosecone and aerodynamic control surfaces
  • 1st flight with three engines
  • 3rd flight Starhopper was able to witness
  • 1st flight to demonstrate switchover to header tanks
Where to watch
Official livestream

Tim Dodd, the Everyday Astronaut!

What happened?

At 22:45 UTC (16:45 local time), under the power of three Raptor engines, Starship SN8 lifted off from its launch stand in Boca Chica, Texas. At around T+1:40 one of three Raptor engines was intentionally shutdown to decrease loads on the vehicle. A second Raptor engine was shut off at around T+3:10. Raptor SN42 continued propelling SN8 until T+4:40 where it gimballed to help initiate the “bellyflop” flip before shutting off.

Using its RCS thrusters and its flaps, SN8 successfully reoriented itself into a horizontal position and began its slow descent to the landing pad. Throughout the descent, SN8 remained extremely stable and demonstrated its ability to control itself during the skydive using its body flaps.

Following a successful, controlled skydive, SN8 lit two of its Raptor engines as planned and initiated the landing flip in coordination with the flaps. SN8 successfully completed the landing flip and became vertical once again.

SN 8 during its landing and flip maneuver with 2 of its 3 engines running. (Credit: Trevor Mahlmann)

Fuel header tank pressure was too low during the landing burn which resulted in the two Raptor engines not receiving enough fuel to land successfully. The engines burned an engine-rich mixture of Raptor and oxygen for the last several seconds of flight. One of the two engines shut down while the other one continued to burn until impact.

Because the remaining engines were unable to produce enough thrust, SN8 landed at a very high velocity which resulted in its destruction. However, the test was still extremely successful as SpaceX was able to complete the vast majority of its test objectives. SN8 achieved many firsts with this test flight and provided SpaceX with all of the data they needed.

SN 8 during impact. The pointy end is still up. (Credit: Trevor Mahlmann)

What’s next?

The data from SN8’s test flight has provided SpaceX with valuable information and will help pave the way for future Starship flights. In the coming weeks, SpaceX plans on launching its SN9 prototype vehicle on a similar trajectory as SN8. 

19 comments
  1. Given what we saw from SN8 I feel confident enough to give SN9 a 75% chance of success by Christmas. Tim and Andrew great job on the feed even with gremlins like bird/fish cam — did like boat cam to because it provided prospective how close people could get to the facility and breaks up the waiting game , Thanks for your hard work this week. Safe Travels friends.

    if you do the video on launch site it would be helpful to know what kind of hotels, restaurants, marinas, RV parks and other facilities are available to the public in the area if we are to go to see a launch ourselves. Thanks again.

  2. I cannot find any reference on the number of engines required during the final ‘flip’ and landing burn. In animations, it shows three. In the flight, the two that were shut off were restarted (at least for a while).
    It seems three might be too much thrust for a nearly empty StarShip, even at minimum throttle (like Falcon 9 only using one).
    Is there any info on this or is it just a ‘wait and see’ situation?
    TIA.

    1. Although there is no official number that I know of, they plan to land with all three engines, but can land with 2 if necessary. At this point, it is probably a wait and see situation, but different missions will require different landing profiles, so we can expect either coonfiguration

  3. Surely the engines were shutdown to gradually decrease this so Starship slowed as it reached its maximum ceiling of 12.5Km. The using its single Raptor engine it traversed so it was in a better position to skydive back to the landing zone. In addition as it had virtually zero velocity it made the flip manoeuvre on its back significantly less risky.

  4. A mi me gustaría preguntar si la excesiva libertad de movimientos de los impulsores, provocaron que uno quemara al otro, y por eso el color verde final.
    También quería saber si usando los tres motores, podría haber completado el vuelo, para poder reusar el mismo cohete, y los motores. Osea, ya que podía explotar, podría haberse usado el mismo cohete para una prueba posterior, sin mantenimiento… llenarlo otra vez y para arriba… Igual hay que reservar más combustible para el descenso, puesto que solo hay una posibilidad en el caso de llevar gente. De todas maneras todo lo que pregunto son especulaciones. Ha sido increíble el salto, y me ha parecido todo una evolución brutal y un salto cualitativo y cuantitativo. Parecía el Razor Quest del Mandaloriano. ?

  5. As a pilot it made me very nervous leading up to the flight, having such an unforgiving landing approach profile. In my experience landing aircraft the landing phase is where you want more options and time, not less. The 1500 agl maneuver to upright was too close to the ground (leaving a low on time condition) to make corrections for any kind of engine hiccup or burp, which seems to happen a lot during landing. That was my preflight gripe. Tim Dodd mentioned more than once that he wanted to see a fuel supply tank switch over with running engines at appropriate times during preflight testing to proof the fuel supply. I would have gone a step further and performed those flow/pressure tests on a test stand capable of flipping the entire airframe during testing of the propellent flows and pressures.

    As it turns out we were both correct. Tim Dodd more than me because his concern was specific, mine more general.

    If your pockets are deep enough, the Elon Musk way works “Build fast, do everything you can think of then let nature do the final calculations in a real flight test.” . Makes for a hell of a show and a very fun life! Go SpaceX, love it!

  6. How can you maintain reliable fuel pickup when the pressurized tank (even spherical shaped) is reoriented wildly and rapidly with respect to gravity?? Using an internal bladder???
    DDB

  7. Truly great coverage of SN8. We are new to this so just subscribed & will send $ support today. Did SN8 have landing legs? If so, what happened? Congrats to you & Elon/SpaceXet al (and you) for putting the excitement of SPACE back inbbn our lives.
    Halifax, VA

  8. Please can you elaborate bit more on this statement ‘ At around T+1:40 one of three Raptor engines was intentionally shutdown to decrease loads on the vehicle.’

    How is shutting down one-of-three Raptor engines can reduce the loads on the vehicle? Are you pointing at by shutting down an engine, the thrust will be lower and reduce ‘total load’ acting on the whole SN8 body?

    Keen to understand this properly.

  9. During some of the slow motion, up-close replays, it seemed to me that the tip of SN8 came to a standstill as the explosion occurred around it. That makes me wonder if the final velocity was actually low enough to land, but the legs never deployed, creating an inferno inside the rocket shell at touchdown. Do we know what the legs would even look like? Could they have been damaged by the flames in the engine compartment after the first motor shut down? Could anyone identify legs in the shots from the engine compartment?

    Overall, an amazing achievement. Thank you for your thorough and enthusiastic coverage.

  10. Also, did anyone (besides SpaceX) measure actual flight profile? Can we estimate propellant load, throttling, fuel consumption, maneuverability, etc from the flight profile? I like the idea of the Superheavy booster not needing a boost back burn or re-entry burn, and even a much smaller landing burn because it will be able to brake in the atmosphere and steer itself back to the landing pad. Although it may be too far downrange to glide all the way back…

  11. Can someone explain how the starship can reliably land on a non prepared surface as would be found on mars. The tiny landing legs just seem all out if proportion to the remarkable height of the vehicle.

  12. There are fast spinning turbines inside starship when it stars to flip back to vertical. I wonder how much extra load and wear the gyroscopic effects acting on the shafts and blades add. (I suppose, that not every shaft is perpendicular to the axis of the flip). If these parts were engineered to the limits for vertical flight, then a flip maneuver could introduce overloads. Though they could run them on 60% or so to ease the loads, or maybe do the flip without running turbines.
    Also the header tank is full, when the back flip starts, but after it starts emptiing I suppose the fuel will be sloshing around wildly inside the flipping tank, so it doesnt seem to be the easiest problem to get out fuel without bubbles at that stage. If they could just do the flip without ignition, and introduce some level of vertical force, enough for the fuel to flow to the bottom, without turning on the rocket, then the header tanks might not be needed, but I’m sure their engineers examined every option. It just would be fun to know what those options were (srb? chute? foldable prop?) and how were they discarded.

  13. It was stated that SN8 touched down at 67 mph. Which was much better than the 400 mph it used during the flop.

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