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Comment by jfengel | Hacker News Reader

Still not orbital?

Well done, of course, props and snaps. But I'm looking forward to it getting up to full speed, and being able to get down from that.

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I think they're holding off on going fully orbital until the Ship engines are relatively stable (they try out different things with them almost every flight, and V3 has a significantly improved engine design too), tile losses are relatively under control and they're either ready to start testing Ship catches, or have tested them.

Right now they're in a comfortable testing regime, getting up to near-orbital speed to be able to verify reentry in realistic conditions, while having the freedom to test dummy payload deployments and freedom to risk losing tiles since they will all definitely burn up or splash down within minutes of the ship reentry rather than floating around in orbit for some time.

If they go orbital, they had better be sure they won't leave a ton of tiles behind, and that they will be able to perform a controlled deorbit.

I think they'll start launching starlink v3 satellites pretty soon, before perfecting reentry let alone rapid reuse. They've demonstrated a zero-gravity engine re-light several times and deployed dummy sats twice, that's all they need to put real satellites in orbit. We could see it on the second or third launch of the block 3 rockets.

I think the tile loss rate will still be important to them before that. Even in such low orbits, any tiles lost would take some time to come down (and might even survive all the way down).

If they can make it so they only lose tiles when in a suborbital trajectory, they may be safe to begin deploying real Starlinks as soon as V3 has proven engine relight.

Oh, do you think so? I thought they're looking very good outside the atmosphere at least, although it's difficult to really tell. I'd be surprised if that holds things up but you could be right.

As you say, it's just difficult to tell, the tile loss seems less dramatic than many used to expect back when the heat shield was relatively early in design, but ultimately only SpaceX knows how much they're passively losing during the coast phase.

All I'm saying is that that's one more factor besides relight that I think will need to be sorted (it might already be sorted, I wouldn't know) before orbit.

> they're holding off on going fully orbital until the Ship engines are relatively stable

They’re still re-flying Block 2 boosters. Hence intentionally leaving off heat tiles (and re-flying engines). Burning for orbit wouldn’t make sense on an, essentially, already-obsolete vehicle.

Block 3 launches on Flight 12. (It also validates a new pad.) Once that is debugged, SpaceX would be ready for an orbital attempt.

The crazy thing is right after orbital they go for propellant transfer. This is something our species has never done, and it’s ridiculously capability enabling if we can get it even within an order of magnitude of cost expectations.

They go up to 98% of orbital velocity on purpose to ensure they don’t create space junk if something goes wrong.

If it gets up to that speed and something goes wrong, is the entire possible crash trajectory over the ocean?

I think it depends on which specific step fails. The farther into flight it happens, the narrower the area over which the debris is spread. But, I think being over the entire ocean is unlikely, since the trajectory intersects with the planet, and that intersection point would also have to be in the ocean.

Correction: the trajectory only intersects with the planet prior to engine relight testing. After that it's at ~50km [1] (though to be fair, if they make it safely through the relight, all testing so far shows they're likely to make it through most of reentry)

[1] https://x.com/planet4589/status/1977917833825730792

There’s a very short period of time where if it exploded debris would fall on the African continent which is an unavoidable risk of orbital flight out of the US. Other than that it’ll either fall in the Atlantic or Indian Ocean.

Yes, as after it leaves the atmosphere and achieves that 98% of orbital speed, its trajectory wouldn't change much even if it exploded - its engines are turned off after ascent that takes ~9 minutes, then it free-falls for an hour to the other side of the Earth. They target a spot in the Indian Ocean near the west coast of Australia (it's coming from the west). In case of explosion debris would fall to the ocean sooner, farther to the west from Australia. More dangerous part of the flight is ascent (when it gains that speed), as its ground path is near some Caribbean islands, and it can cause problems like on flight 7:

> Around three minutes later, Ship 33 exploded over the Turks and Caicos Islands, causing debris to litter the Caribbean islands, Puerto Rico and the British Virgin Islands. While no injuries were reported, the debris caused minimal damage to infrastructure in Puerto Rico and the British Virgin Islands, and prompted airspace closures in the region for over an hour. The FAA ordered SpaceX to perform a mishap investigation into the breakup, grounding Starship until the inquiry was complete.

https://en.wikipedia.org/wiki/Starship_flight_test_7#Mission...

It's fully orbital speed but the trajectory is steep enough such that it'll come back down in the Indian ocean whether they maintain control or not.

Technically, the trajectory of the last couple of flights is a transatmospheric orbit, meaning that if the Earth didn't have atmosphere, it would be an actual orbit.

https://en.wikipedia.org/wiki/Transatmospheric_orbit

Are you going to say the same thing about their 500th suborbital test?

They go above orbital velocity, they are avoiding an orbital trajectory.

A rapid unscheduled decomposition at that height will accelerate at least some junk into orbit.

They're testing specific things with no need for full orbit, although I think they reach verrrry close to orbital velocity. They want the payload dummies to 'de-orbit' quickly (from a suborbital trajectory). They could easily have gone orbital if they wanted to. I guess we'll see orbital demonstrations after a few splashdowns of v3 stack early next year.

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