Will JWST be as durable as the hubble telescope? JW Space Telescope is designed for a 5-10 year mission duration. Seeing as Hubble and other space missions have paved the way for JWST for reliability issues, It even has zero friction gyro's with 100+ years mean time before failure. Is it reasonable to think that JWST can last longer than Hubble?

JWST will orbit a Lagrange point in earth's shadow and will be 4 times further than the moon, around 10 days of travel away, and NASA states that JWST won't be serviceable. Why?

Why are JWST's fuel limitations so short? Are there no provisions for refueling? even a refueling craft? How many gallons of dinitrogen tetroxide ($N_2O_4$) as oxidizer and hydrazine ($N_2H_4$) will it contain?

Surely NASA are secretly hoping for a 20 year mission?
Hubble was in low earth orbit, and was always intended to be serviceable. In fact, the original plan for Hubble was to have the space shuttle carry it down from orbit and take it back up, but they decided that was too risky compared to servicing in orbit.

JWST, on the other hand, will be at the Earth/Sun L2 Lagrange point, like WMAP and Planck before it. The distance to that point is 0.01 astronomical units, which is about 1.5 million kilometers from Earth's center. The Moon's orbit around the Earth is about $1/4^{\mathrm{th}}$ of that. So, a manned servicing mission would be an unprecedented project (beyond Apollo), and an unmanned mission, also unprecedented, would face automation challenges from the 5 second light travel time (10 second round trip).

Because the L2 Lagrange point is only meta-stable (stable to offsets in two directions, unstable along the Earth-Sun line), JWST will have to expend fuel on station-keeping just to stay there. It needs to stay there because it can only be as cool as it needs to be by using the Earth as a sun-shade - those tennis court sized shades built in are actually to shade JWST from the thermal radiation of Earth &amp; the moon.

Put simply, it would be cheaper to build and launch another JWST than to service the existing one.