SpaceX Starship - IFT-3 - Starbase TX - Launch Thread and Post Launch Discussion

Launch Date: March 14
Launch Window: 7:00 am CDT (9:00 am EST, 13:00 UTC)
Launch site: LC-1 - Starbase, Boca Chica Beach, Texas
Core Booster Recovery: Expended in Gulf with a landing burn
Starship Recovery: A controlled reentry through the atmosphere to a terminal velocity splashdown in the Indian Ocean
Booster: Super Heavy Booster 10
Starship: Starship 28
Mass: No mass simulator mentioned
Orbit: LEO-ish
Yearly Launch Number: 26

A SpaceX Super Heavy and Starship launch vehicle will launch on its third not quite orbital integrated flight test designated IFT-3. The mission will attempt to place Starship into a nearly orbital trajectory that will attempt a controlled reentry through the atmosphere to a terminal velocity splashdown in the Indian Ocean . The Super Heavy booster will attempt a landing burn in the the Gulf of Mexico where it will likely be destroyed. This is a further test of Stage 0, the booster, full power ascent, Max-Q, stage separation using the new hot staging, a booster stage test of a hard turn and boostback, full burn boost of Starship to space and sub LEO, Starship will do one partial orbit, simulate a de-orbit burn, test tiles and heating from atmospheric reentry, until it has a splashdown in the Indian Ocean.

It has also been determined that for this test flight there will be a fuel transfer test done on Starship for NASA's Tipping Part contract. The Starship will also test its payload bay door in zero-G for a test of future Starlink 2.0 deployments.

 

[Electroman]

Can't be 100% sure but isn't the ship skin made of 3mm SS?

SS is a reasonable conductor so we can assume that if the outside skin temperature is 1300K then the inside skin temperature will also be 1300K. As far as I am aware the LOX and CH4 tanks are single skin so both of these liquids will be seeing that 1300K. I would expect some pretty significant heating of the remaining liquids and/or vapour.

.. so maybe you need tiles inside too

 

[ecarfan]

I seem to recall SpaceX saying that the engine relight wasn't performed because of the roll.

Correct, SpaceX posted afterwards:

Starship did not attempt its planned on-orbit relight of a single Raptor engine due to vehicle roll rates during coast.

However, I wonder if the roll during the coast phase was intentional and controlled and then plan was to null it out before the relight attempt but they were not able to do so.

 

[ecarfan]

So does it seem like at T+43 when it appears that the ship is trying to position itself for reentry that it changes its attitude a lot more than is necessary and then keeps changing as it descends? It’s very hard for me to figure out the attitude of the ship relative to Earth just based on the single camera view and the ship graphic at the bottom which only shows movement in a single dimension.

It seems like initially when the plasma heating is visible the ship is reentering backwards (aft end “up”) and later the ship graphic shows radical changes in pitch in ways that don’t look believable. But what do I know, not a rocket scientist…

 

[mongo]

During prop loading there were clouds of condensate coming off the ground extending out into the wetlands area but the wind wasn’t blowing it that way, in fact it was blowing the opposite direction. I don’t understand that.

View attachment 1028340View attachment 1028341

There's a dump pipe/ catch basin for the cryo over there, then the wind blows it the other way.

 

[mongo]

However, I wonder if the roll during the coast phase was intentional and controlled and then plan was to null it out before the relight attempt but they were not able to do so.

Hard to say, it was stable for a while until a drop out and the door test.
8:35 MECO
12:10 still stable
16:20 light pattern through cargo door indicates rotation
19:26 rotation

 

[JB47394]

12:10 still stable

Roll stable, but it's slowly yawing. I wonder if they were exercising the various thrusters to establish control of the vehicle on all three axes only to find that the "clockwise" roll thrusters failed. So they had imparted a slow counterclockwise roll during testing, and were stuck with it for the rest of the flight.

The pitch thrusters came in during reentry, but it's not clear to me if they were working correctly. It's pretty difficult to orient a vehicle in pitch while it's constantly rolling.

 

[HVM]

There's a dump pipe/ catch basin for the cryo over there, then the wind blows it the other way.

Liquid methane / oxygen is heavier than air and flow downhill, then it evaporates and is carried away with breeze.

 

[scaesare]

Yeah... may be... I took that to be rapid flap motion with control system trying to adjust to it tumbling.... but it also does seem to be a bit more abrupt thatn the rear flap the cam is aiming at...

Upon re-watch, I also think that much of what looked like black material may simply have been ice in the shadows of the ship as it rotated... at 1:19:17 a large dark chunk enters on the bottom of the frame, and as it passes the belly of the ship it curves towards the left of the frame and at 1:19:19 it enters the sunlight and it immediately becomes clear it's a white piece of material... presumably ice and not a tile...

A bunch of the other smaller pieces do similar.

Noticed this in watching Manley's video:

Missing tile the middle there?

 

[ecarfan]

Roll stable, but it's slowly yawing. I wonder if they were exercising the various thrusters to establish control of the vehicle on all three axes only to find that the "clockwise" roll thrusters failed. So they had imparted a slow counterclockwise roll during testing, and were stuck with it for the rest of the flight.

The pitch thrusters came in during reentry, but it's not clear to me if they were working correctly. It's pretty difficult to orient a vehicle in pitch while it's constantly rolling.

All this discussion about thrusters makes me wonder; with half the ship covered in TPMS are there any thrusters on that side? I assume not. Does that then make ship thruster control more difficult?

 

[Buckminster]

https://twitter.com/x/status/1768675720014791030

 

[ecarfan]

Wow, that is illuminating. To my non-expert eye that roll looks excessive but it is greatly speeded up.

 

[JB47394]

All this discussion about thrusters makes me wonder; with half the ship covered in TPMS are there any thrusters on that side? I assume not. Does that then make ship thruster control more difficult?

The below is my understanding. I've been unable to find a lot of information on the details of Starship's reaction control system.

That said, here's an image of a Starship venting all over the place. That top vent with a red circle has a twin to the left. I believe those are two of the roll thrusters. There may be others.

I'm pretty sure there are no thrusters on the tile side right now. At one point, I know they had vents of some sort on the tile side because we saw tiles blown off during venting on early vehicles. I assume that they moved that vent.

You can put thrusters pretty much anywhere you want on the ship and have it work out, so long as some of the thrust is going in each of X, Y and Z directions. It then falls to computers to sort out which thrusters to fire to accomplish any given maneuver. You may end up with some unwanted translation, but that should be pretty minor relative to the orientation changes you're making. Also, with the center of mass moving around as a result of tanking, detanking and firing the engines, calculations would be needed for efficient use of even pure roll, pitch and yaw thrusters.

SpaceX apparently started with methalox thruster packs, and developed them to the point of testing. In the end, they ditched them in favor of ullage thrusters in order to accelerate the process of getting to orbit. Here's Scott Manley talking about it. I don't know if they're going to stick with the ullage thrusters or move on to the methalox thrusters once they actually have a need to do a lot of maneuvering in space.

I wonder if this Starship was not particularly maneuverable because of the use of the weaker ullage thrusters.

Note that the Space Shuttle has thrusters amid the tiles, but not on the underside, where the plasma builds up. I have no idea if SpaceX will try to put thrusters anywhere in their tiled area.

 

[MrFixit1094]

That assumes that the FAA issues launch license process speeds up because with each flight there are fewer issues that need investigating

Although sometimes as more issues get solved, the last remaining ones can be especially difficult technically. This could result in the the pace being set by the ability of SpaceX to solve more difficult technical problems rather than the licensing / approval process.

Hopefully they will not uncover problems that are 'fundamental'.

Reentry is a very difficult problem. I hope they were able to gather enough data while the vehicle was still alive to nail down exactly what happened.

 

[ecarfan]

Interesting to see visible pressure waves during liftoff.

 

[ecarfan]

(EDIT: oops, I see this video was posted last night in the Starship general development thread)

Great video from LabPadre showing all three test flight videos time-synced to demonstrate the remarkable progress achieved so far.

 

[JB47394]

More pressure wave video. Watch 1:40. It looks like the pressure waves are exploding outwards from the end of the shock diamond train. It may be an illusion, but I wonder if that's what happens when the pressure is no longer structured into shock diamonds. I wonder if something can be engineered to change that effect. I'm thinking of how aircraft are being reshaped to reduce sonic boom effects. Naturally, they wouldn't extend physical structure down that far, but I wonder if the exhaust can be shaped in some way.

 

[scaesare]

More pressure wave video. Watch 1:40. It looks like the pressure waves are exploding outwards from the end of the shock diamond train. It may be an illusion, but I wonder if that's what happens when the pressure is no longer structured into shock diamonds. I wonder if something can be engineered to change that effect. I'm thinking of how aircraft are being reshaped to reduce sonic boom effects. Naturally, they wouldn't extend physical structure down that far, but I wonder if the exhaust can be shaped in some way.

Interesting... is this where the exhaust plume is going from super- to sub-sonic and in essence a sonic boom?

If so, it would seem that on the pad, the exhaust hitting the ground forces that slowdown, but once sufficiently in the air it's just the natural deceleration within the atmosphere...

 

[scaesare]

https://twitter.com/x/status/1768675720014791030

Ahh that rotation just before the end of the video puts the side of the ship (the side away from the camera) down, where the plasma would then be coming up both the shielded belly as well as the unshielded top side... that can't be good. The video ending right after that is probably not coincidence.

 

[scaesare]

Somebody on NSF did count of missing tiles on a frame of video:

Looks like 8 he could see... feels like less than previous flights...

 

[Electroman]

How did the OLM infrastructure fare ? Any damage?

Experts like me have pointed out many times, having an exhaust tunnel is the only way to go. Please tell me that I am correct and SpaceX is wrong.