James Webb Space Telescope Launch Postponed
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I’d be excited about it if it wasn’t taking this long. My friends and I were talking about this telescope in high school physics class in 2004.
The hype around the telescope is to the point of a down-on-his-luck divorced dad that consistently overpromises and underdelivers. (Remember that Sega Dreamcast I promised you when you were little for Christmas one year? Well, here it is now that you are all grown up.)
It’s an exaggeration, but I’ll believe it when I see it.
At this stage I think it would have been faster, cheaper and lower risk to have either developed a launcher that could have fit it inside a fairing with a more conventional and less compact shield......Or would have been acceptable to take the performance hit to either stick this thing in Earth orbit so it could be serviced.....Or have given it a less effective but much safer and more conventional chassis so it could have gone to L2 without the massive risk of failure.
EDIT: I know that those alternatives would yield suboptimal results but you have to balance capability and cost with risk. JWST is 20 years in the making and very very expensive. This thing will only have an operational life of 10 years even if everything goes to plan. So under the best case it wont have the staying power and upgradability of Hubble unless someone figures out a cost effective way to get astronauts to L2 and back.
They are, for a generous value of "they". For the cost of making this observatory fit on an Ariane 5, SpaceX is developing a 9-meter reusable launch system that can be run in a carbon-neutral fashion. It would still require folding, but nothing beyond conventional folding techniques that have been used since the 1970s.
RTGs are also very heavy and do not generate much power; they are useful for the outer solar system because solar power is not viable there due to the inverse square law. At this distance from the sun, solar is a no-brainer.
Normally, space telescopes will be built like Hubble or Spitzer where the mirrors are inside a cylinder which keeps light out from all directions except where the telescope is aimed. Its also insulated to keep heat from messing with measurements.
JWST's mirror is so large that they couldn't build it this way because no launcher existed at the time with a large enough payload fairing to fit it. So instead of a conventional, and otherwise superior in every other way, cylinder they came up with a clever origami folding sunshade. For comparison Hubble has a 2.4 meter main lens and JWST has a 6.5 meter lens. Its so large they couldn't reliably make it out of one element either so its actually several hexagonal elements put together. This is a popular technique for large telescopes.
For power JWST just has solar panels. L2 isn't that much farther from the sun than earth is so it gets sufficient power this way.
But unlike Hubble's reaction wheels JWST uses RCS thrusters to change its orientation. There are pros and cons. RCS is much more reliable than reaction wheels, a lot of satellites met a premature end because their reaction wheels stopped working. But RCS only lasts as long as you have fuel. They gave JWST enough for an estimated 10 years of operation.
Specially because it is literally news from yesterday, already published in a better source: https://www.nasa.gov/feature/james-webb-space-telescope-laun...
Leaving the title as is may trick people into thinking it was postponed again.
Let's just hope the series converges.
Zeros paradox is at least just a paradox.