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Comment by mcculley | Hacker News Reader

> "Success was defined as the rocket leaving the launchpad."

I am confused. Everything I read before the launch said that it was intended to reach orbital altitude and make it around the Earth.

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This is a bit of spin by SpaceX. Blowing up the pad would be a serious failure and would be a large and costly setback. But they obviously didn't achieve the goal of the test flight here. It is a test flight, so it's not a complete failure and not entirely unexpected. But it's not a full success either, significant parts that were planned to be tested could not be tested because the rocket failed early.

Well the flight plan was to throw both stages into the ocean, so they couldn't have been overly confident about getting that far.

I'm pretty sure they planned on the booster to land on a barge in the ocean

No barge, just a touchdown on the water.

> significant parts that were planned to be tested could not be tested

I don't think "planned" is the right word - the right word is "hoped".

For the record, they did blow up the pad.

At least there was no explosion on the pad, which would have been much worse.

This test launch was never planned to actually make orbit. It was an "orbital test flight" only in the sense that it was intended to demonstrate system performance that would basically have been enough to reach orbit; the original plan was that they'd reach velocities and aerodynamic stresses similar to an actual orbital flight, test stage seperation, both stages, and part of the re-entry, then crash into the ocean, all on a sub-orbital trajectory. Something apparently went wrong at stage seperation.

> This test launch was never planned to actually make orbit.

Very, very technically true, but not really. Their target trajectory was only a few tens of m/s short of orbit.

> aerodynamic stresses similar

Right, within one percent.

Right. It was not my understanding that they "planned to actually make orbit". This is why I used the same words they used, "orbital altitude".

That might have been the flight plan. When drawing these up you don’t typically mark down "experiences an unexpected rapid disassembly a few minutes after launch.”

I thought they were very clear on how they defined "success".

This is progress, and admirable, but not a success according to their previous statements.

They defined success as being able to gather information. They did that :)

They've been saying (Elon at a minimum) multiple times that they expect the first flight to end in a giant ball of flames. That there's a "if everything goes extremelly well" plan that reaches quasi-orbit and lands back nicely... doesn't make this the expected goal. It's not like they can submit a flight plan to the FAA that's "we'll launch and explode somewhere along the way". They need to draw up a nominal plan, with the full understanding (by reasonable people) that the flight really isn't expected to actually fulfill that entire plan.

It's pretty amazing that the rocket went past the launch pad, yet alone survived past max-Q to begin with!

Why is it amazing that it left the pad?

It’s the first time this rocket has had all 33 engines attempt to light and fully throttle up.

SpaceX has no test facility capable of withstanding a full thrust booster test on the ground.

Also SpaceX has more boosters and ships complete and in various stages of assembly. A complete loss of the pad would have been much more damaging to the program.

It's a giant shaking and trembling structure built in a fail-fast iterative manner using unexpected materials (stainless steel) and processes (regular welding). Assemble all this in history's largest rocket ever, and expect everything to go perfect the first time?

I wouldn't have been surprised if the whole thing shook itself apart on the lift pad and blew up.

I don't know about you, but when I rapidly build and assemble large complex structures like a cowboy, I certainly expect a ton of failures on my first trials. When stuff goes much further than I expected, I'm in awe and disbelief.

From the livestream (at about T-30:00):

“We consider any data received that helps inform an improved future build of starship a success. From a milestone standpoint, our main goal is to clear the pad. Every milestone beyond that is a bonus. The further we fly, the more data we can collect.”

It's a matter of expectations. No one set out with the goal of blowing up a rocket but it was very much an expected likely outcome. By clearing the launchpad, the team met their milestone. Anything beyond that is simply additional data to improve the next iteration.

I'm no fan of the SpaceX model but if it works for them and the safety of those on the ground is prioritized, it seems to work better than any other model tried here.

Well, even if your success factors are waaaay early, you have to account for the fringe event that everything keeps working out. So yeah, they filed a flight plan because theoretically the ship could get there.

Musk was saying it was a 50% chance the rocket blew up on the launchpad. Their sole hope was that it made it in the air, leaving the launchpad unscathed and quickly usable for future launches.

He actually said 50% chance of reaching orbit.

> “I'm not saying it will get to orbit, but I am guaranteeing excitement. It won't be boring,” Musk promised at a Morgan Stanley conference last month. “I think it's got, I don't know, hopefully about a 50% chance of reaching orbit.”

I stand corrected. That apparently was indeed the original context of his statement. The Internet has ways of morphing words.

I do recall he did express some level of concern about the launch pad being damaged if the rocket failed to launch though (it still looks like it was damaged to some degree from the launch.)

He also said there was a 80% chance of reaching orbit this year. Which doesn't seem like a high number.

That was the stretch goal. They made it clear several times on the webcast and in tweets that clearing the launch pad was the primary goal and further than that to gather lots of data. The farther they got, the more data they gathered and the more successful it was. You can have varying degrees of success and still be successful.

That was the goal, but failures are to be expected at this stage of testing. Clearing the tower was a primary goal since a ground level explosion would cause a lot of expensive damage. Clearly there were multiple failures.

The Chief Twit said "anything other than blowing up the launch pad is a success."

Sounds like he moved the goalpost.

He's been saying this for literally years. That the pad is stage 0 and if they don't blow up the pad, they're happy.

I think he said the exact same thing about the first Falcon Heavy launch.

I am not disputing that this is progress. It is an admirable effort. I am happy for them.

I interpreted literally the words they used about the plan for today's launch.

It's a difference between "definition of success" and "the plan". They can't just say "we want to get off the pad and whatever happens afterwards, meh", they have to point it somewhere. So they plan out a whole flight to maximize useful data per additional success, but consider some subset of the plan to be an overall success.

I might go to the grocery store with a list of five things, but I only really need two things. Coming home with 3 things would be a success.

I am happy that they had a partial success. I remain unconvinced that it was a success as defined by other things they said.

Who cares? It's a lot of arguing over semantics that doesn't end up meaning anything in the grand scheme of things. SpaceX continues making progress on the development of Starship, and the tiny little mishaps that depend mostly on chance along the way don't end up actually mattering in the grand scheme of things.

I don't think SpaceX cares about your uninformed opinion

I agree with you. The only information I had is the words they used.

The plan was a range.

On one end of the spectrum, Starship detonates on the pad and they have learned very little and have a year of work to do rebuilding the pad.

On the other end of the spectrum, everything works flawlessly and Starship survives re-entry and smacks into the ocean off of Hawaii.

They achieved a result in the middle. Neither total failure nor total success, and well within their stated expectations for this attempt.

They defined success up front as being able to gather information. They did that.

Oh, In that case there’s no such thing failure then. Lucky for them

Exploding on the launch pad would've been a failure.

surely not - they would have gathered information

there is something about this launcher and the launch that looks exeedingly wrong to me cf a saturn v (i realise spacex is trying to launch larger masses)

you should write elon and tell him what he's doing wrong and how saturn v did it right

on twitter?

It’s sort of difficult to call it moving the goal post when that goal post was set well before the test attempt. That’s maintaining the goal post.

Moving the goal post pre-event is a new one for me.

Thanks for the laugh.

If you watch the launch broadcast, the hosts set the expectation that they success meant achieving thrust-to-weight of >1 and clearing the launch facility.

Furthermore, we don't know there was a failure to separate. If I had to guess, once the vehicle was in an unstable attitude outside of the nominal flight path, they triggered the self-destruct and purposefully didn't try to separate.

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