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Comment by baq | Hacker News Reader

I'm a SpaceX fanboy but let's not get too enthusiastic. Arianne has had no vehicle loss since their first flights and is considered reliable enough to launch the James Webb. Nobody in their right mind would put that on a Falcon 9 even if they paid them.

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I think one reason that the Arianne and James Webb are such a good fit are because they are designed on the same model. What would a telescope designed around a SpaceX model look like? Self assembly in orbit? Networked independent telescopes? Ariannes are pets, not cattle. What would it look like if we rethought that?

You could argue JWST will be doing self assembly on orbit with the deployment of the primary mirror. There is some very fine wave front adjustment that needs to happen there. They are putting a 6.5 meter mirror on orbit! That alone puts it in a tie for the 14th largest telescope primary mirror when you include Earth-based ones. Very impressive in my book.

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

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

Absolutely! I'm not said it isn't impressive, and it will have great research value. I'm just wondering what might be achievable with different assumptions. Instead of 1 6.5 meter telescope, how about 20 1 meter telescopes?

For the price NASA is paying for JWT I would only launch it on a gold spacecraft powered by unicorns.

It seems to me, that to some extent the cost of launch feeds into the cost of satellites. Spacecraft have to have reliability in the extreme because it's so expensive to put them in orbit, and they're very expensive to service if practical at all.

Is that due to the larger history of success of the Arianne family of rockets?

Certainly part of it. I think the JWST is supposed to be a collaboration between NASA, CSA, and ESA. The European contribution is the launch vehicle.

Rockets tend to get more reliable as they get older because designers find all the various failure modes and fix them. It's normal to have a couple of rapid unplanned disassemblies in your first ten or twenty flights. Ariane 5 did. Falcon 9 did. Basically everyone but ULA does. The only difference between the Ariane 5 and Falcon 9 is that the Ariane 5 has a lot more flights under its belt.

I was interested in your comment about Ariane 5 having a lot more flights under its belt, as it has seemed like SpaceX has ramped up their launches considerably, and the article talks about 5-10 launches per year for the new Ariane 6. So I went and looked up the details...

For anyone interested, Ariane 5 has had 98 launches (93 successful) and Falcon 9 has had 54 launches (52 successful).

However, Falcon 9 has 18 launches in 2017, and is on track for 28 this year (8 completed so far), whereas Ariane 5 had just 6 in 2017 and is on track for 10 this year.

It’s definitely true that Ariane 5 has more experience under its belt so far, but that seems to be changing quickly, and with Ariane 6 resetting some of that experience, I think SpaceX are at a significant advantage here.

Another way to look at it is that the Ariane 5 has 5 failures across less than 200 rocket engine uses (ignoring solids), while SpaceX has 2 failures across 540 rocket engine uses.

spacex also had a total vehicle and payload loss while standing on the pad with engines off, so your metric should be more like 1/540... but then you want to count test firings at mcgregor and every wet dress rehearsals/static fires.

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