[kortilla]

It’s not a significant challenge compared to what they’ve already done.

Each of those previous tests could have easily gone to LEO running the engines just a tiny bit longer.

OPs point is that they intentionally didn’t.

achieving LEO means you need a relight to have a controlled reentry. You don’t want that if you want to avoid countries being mad at you while you iron out those controls

[JumpCrisscross]

> It’s not a significant challenge compared to what they’ve already done

I don't know an aersospace engineer, within SpaceX or without, who would agree. When you increase speeds you increase energies faster. That has an effect on everything from pump performance to re-entry physics.

> Each of those previous tests could have easily gone to LEO running the engines just a tiny bit longer

Which risks recovery. Given they were replacing their Raptors in the next refresh, pushing an already-obsolete engine for shits and giggles doesn't make sense when you can get good data on e.g. skin performance.

> achieving LEO means you need a relight to have a controlled reentry. You don’t want that if you want to avoid countries being mad at you while you iron out those control

There is zero indication diplomatic pressure has been a constraint on the U.S. space programmes in the last couple years.

[bryanlarsen]

They didn't have to increase speeds, they already achieved orbital velocity. To circularize all they need to do is relight. Relighting an engine is very difficult for an engine like Raptor, but they've already demonstrated relight.

[JumpCrisscross]

> They didn't have to increase speeds, they already achieved orbital velocity

My undertstanding is Starship didn't hit 17,000 mph [1]. LEO orbits tend to be 17,500 mph and up.

Like, I'm not arguing that SpaceX couldn't have circularised on previous tests. But it would have added material risk without any reward. And taking a ship, particularly a re-usable one, particularly a novel one, into its first orbital flight is always exhausting and novel.

[1] https://www.thespacereview.com/article/4761/1#:~:text=As%20S...

[kevin_thibedeau]

It is like a runway taxi test on a plane that is fully capable of flight. Sometimes the plane takes off unexpectedly but the plan is not to do it. Starship can do orbital insertion now despite no plan to do it yet.

[kortilla]

Spacex explicitly on the streams said they shut off the engines early to avoid orbit. I don’t know why you would argue against them

You’re also incorrect that a separate burn is required for orbit. You only need to do that if you want a circular orbit.