[jpgvm]

I think spending Christmas wringing your hands unsure if your $10B decades-in-development baby is going to make it to orbit sounds incredibly stressful...

It's going to be awesome for us to watch but I feel for all the folks that worked on this.

[ajross]

FWIW: given the extraordinarily complicated mechanical design, merely reaching orbit is the "easy part". The real imagined disasters won't happen until the mirrors assemble.

[mortenjorck]

True, though it’s also worth considering that Webb is going far beyond “orbit“ as we generally think of it. I don’t know how much has been launched all the way out to L2 before, but it’s probably an order of magnitude less than what’s in Earth orbit.

[krisoft]

> I don’t know how much has been launched all the way out to L2 before...

There is a handy list on wikipedia: https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po...

Your intuition is quite right, there is way less satellites parked around L2 than in low earth orbit for example.

But that doesn't really pose too big of a challenges in itself. It is of course far, both distance wise and energetically.

The main complication often mentioned is if something is wrong with the telescope it makes it very unlikely that a crew can visit it to fix it. The way for example how they repaired Hubble is unlikely to happen with Webb.

[ajross]

Meh, but there's nothing to hit in space. The energy required to reach a routine geosynchronous orbit is already ~85% of escape velocity. The added boost is minimally more dangerous and the trip is just empty hours. "Time" does kill spacecraft, but not often.

The Webb self-assembly is absolutely where the scary bits lurk.

[jpgvm]

Yeah valid. Though the whole "hurtling upwards on top of a bomb" part is still definitely scary in it's own right.

[argiopetech]

Particularly given the launch record of the Ariane 5 platform. I did some quick research, and no modern launch platform has as high a mission failure rate (4.5%.) The Delta family comes close at 4.4%, but that's a 50yr launch history. The Delta 4 iteration has had no failures.

[jacquesm]

As I wrote elsewhere, the bulk of those failures were in the first 15 launches, after that it was a very long string of one success after another with one partial failure in 2018.

[Symmetry]

The Ariane 5 is batting 106 for 111 which is pretty good odds and perfectly respectable for a heavy lift vehicle... but not so much so that I don't wish it was launching on an Atlas 5 instead.

[GuB-42]

Ariane 5 had some early problems, the first failure even became a case study in critical software development. But it had only had one partial failure after the 17th launch: the payload was launched to the wrong orbit because the wrong coordinates were put in the computer. A huge QA problem but not the fault of the launcher which did exactly as told.

Now, both Ariane 5 and Atlas 5 are extremely reliable, mature rockets.

[jacquesm]

Four of those were in the first 15, the last recent one was in 2018, and was a partial failure.