Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Webb flies Ariane 5: watch the launch live on 25 December

esa.int

Post reply on HN
Print view View original

21–30 of 188 posts

Re: Webb flies Ariane 5: watch the launch live on 25 December

#21

Post by mortenjorck »

ajross wrote: post #8
jpgvm wrote: post #4

Earlier quoted context omitted.

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.

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.

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.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#23

Post by khuey »

adventured wrote: post #13
amichail wrote: post #9

Why isn't SpaceX doing this?

The launch partner/platform wasn't chosen recently and it's part of what ESA is providing as a partner in the program. "In exchange for full partnership, representation and access to the observatory for its astronomers, ESA is providing the NIRSpec instrument, the Optical Bench Assembly of the MIRI instrument, an Ariane 5 ECA launcher, and manpower to support operations. The CSA will provide the Fine Guidance Sensor…

"not recently" is underselling it a bit. ESA agreed to launch it before Falcon 9 (let alone the Heavy version) had ever flown.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#25

Post by jcfrei »

_fizz_buzz_ wrote: post #14
amichail wrote: post #9

Why isn't SpaceX doing this?

Ariana 5 can transport a larger/heavier payload than Space X rockets. And even then the telescope has to be folded up in this really complicated way.

A fair comparison would be to Falcon Heavy (Ariane 5 uses boosters as well) which has about twice the payload capacity. Just doesn't yet have the launch history required for such an important payload.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#27

Post by daenney »

gfodor wrote: post #22

Interesting they found a way to add a hidden risk variable to the launch, by sending it up on a day people are having to choose to not be with their families. Have a bad feeling about this :/

“They” didn’t find anything. It wasn’t originally planned for tomorrow. The weather found a way. There’s only so much wiggle room and launch windows.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#28

Post by sidkshatriya »

fnord77 wrote: post #17
amichail wrote: post #9

Why isn't SpaceX doing this?

ariane 5 has had 111 launches. Falcon heavy has had 3. the falcon heavy probably didn't even exist when they were drawing up the contracts

I think Falcon heavy is not needed. Webb's weight is ~6200 kg. Falcon 9 is 8300 kg to GTO (Geostationary transfer orbit). This leaves about ~2000 kg fuel equivalent to spare which should be more than enough for the special location Webb is aiming for.

But yes, the contract for the webb launch was probably locked a very long time ago.

(Though it's also possible that Falcon 9's fairing wont be able to accommodate Webb)

Re: Webb flies Ariane 5: watch the launch live on 25 December

#29

Post by architravesty »

ur-whale wrote: post #18
amichail wrote: post #9

Why isn't SpaceX doing this?

> Why isn't SpaceX doing this? Reliability (as in: established track record). Although, if Ariane decides to explode tomorrow, this comment will look ... odd.

Falcon 9 has a better track record than Ariane 5 at this point, but SpaceX wasn't really a thing at the time these contracts were signed.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#30

Post by ajross »

mortenjorck wrote: post #21
ajross wrote: post #8

Earlier quoted context omitted.

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.

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.

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.

Post reply on HN