Hacker News Reader

Comment by raisin_churn | Hacker News Reader

Part of the huge cost to develop it was getting a mechanism that could deploy the mirror segments into a large enough array with sufficient accuracy, a task that would be dramatically simplified by a a launch platform with a wider fairing and greater mass to the L2 Lagrange point. So yes, if SpaceX Starship was available, it would've saved a ton of money on JWST, albeit mostly by relaxing the design parameters of the telescope rather than through cheaper launch costs.

View on HN

An engineering way to deal with inaccuracy is to make things adjustable with feedback.

It's like the silly analogy I hear now and then that sending a probe into the solar system is like throwing a baseball from LA to NYC and hitting a small target there. It isn't like that at all. The probes undergo course corrections as necessary.

> if SpaceX Starship was available, it would've saved a ton of money on JWST

How much? How much did it cost for the actual JWST? Do you have any evidence of this great cost?

The glorification of Musk's ego is endless. Can JWST see the farthest reaches of it? Is it expanding or contracting?

I think OP is saying they would have had the space to simply built one large mirror instead of many different mirror segments that require complicated motors and moving parts to deploy into position.

The mirror segment deployment technology is surely a significant percentage of the cost.

> surely

Is there a more common or obvious trap of reasoning? If 'surely' worked, we wouldn't have needed the Enlightenment, science, or the JWST to learn about the universe.

IIRC (much stronger evidence than 'surely', but still lacking), it's in fact not significant to the cost.

>IIRC

Is there a more common or obvious trap of reasoning? If 'IIRC' worked, we wouldn't have needed the Enlightenment, science, or the JWST to learn about the universe.

This has nothing to do with Musk. A larger payload fairing diameter means fewer/no elements of the mirror have to be folded up for launch, means reducing or completely avoiding the multi-hundred step deployment procedure, the design of which was both an enormous engineering undertaking and most of the over 300 single-points-of-failure[0] in the final design. It doesn't have to be the SpaceX Starship, but there's no other launch vehicle currently in development with a comparable payload diameter. Since it's a purely hypothetical as the entire design process took place with launching on Ariane 5 in mind, I have no idea what the cost savings would be, but it is self-evident they would be considerable. The thing isn't made of $8B worth of metal, the cost was in engineering it.

[0] https://www.space.com/james-webb-space-telescope-deployment-...

> it is self-evident

Nope! It doesn't cost 8 billion to unfold a mirror. Seems like a rather straightforward mechanical problem to me. And your baseless theories and mine are worth nothing without evidence. That's the reason we built the JWST - we need evidence. Baseless nonsense is the stuff of cults of personality, not knowledge. We need much more of the latter and much less (i.e., none) of the former in our society.

Okay, engineering time costs money. Absolutely staggering amounts of engineering time were spent ensuring that the extremely intricate, highly prone-to-failure deployment process would be successful. With a larger payload diameter, the mirror deployment process could have been dramatically simplified, thus saving some percentage of the staggering amounts of engineering time expended, thus saving some percentage of the billions of dollars spent to get the telescope to the launchpad. I do not care what company produces the launcher with the bigger payload diameter, OP specifically asked about Starship, and the answer is YES, a launcher with a significantly larger payload diameter than what is currently available, like Starship if it is ever successful, would make an undertaking like the JWST easier to design, and thus cheaper to design. I dislike Musk as much as any disinterested party (I'm sure people he's scammed with his "FSD next year" or people he's sexually harassed, and definitely his children dislike him more), but a better launch vehicle WILL make bleeding-edge space missions cheaper, and better. That is wholly unrelated to one obnoxious egomaniac.

It's pretty trivial to tell that a large portion of JWST's delays were related to the unfolding mechanism (first building it, then the 5 years of delays from a ripped sunshield, loose screws and more), much of which would be rendered unnecessary by Starship's wider payload bay. Thus of course it would've saved a ton of money on the telescope. The telescope wouldn't have needed so much testing if it didn't have 344 single points of failure, and it wouldn't have that many of those if it didn't need its unfolding mechanism.

If that isn't convincing enough, the budget plan including all folding mechanisms etc before testing was $6.5B, so the $3.5B extra was spent entirely on testing and repairs. Thus, if a folding mechanism was not needed, they could have saved at least that much on testing and fixing said mechanism.

Might be a good idea to take off your blinders before complaining about someone being more successful than you. Since your jealousy is blinding you so much, it would have been just as convenient for costs if any other rocket had a wider payload fairing than Ariane 5.

And if SpaceX was available with a larger payload, engineers would have built the same folding telescope, only much larger and more costly.

Reply on news.ycombinator.com