After a delay of more than a decade and at a cost 10x its original estimate, the James Webb Space Telescope is finally on its way to its launch site in South America. If all goes as planned, on 18 December, a European Space Agency Ariane 5 rocket will boost the telescope into its orbit around the 2nd Lagrange point (not the Earth!):
This position allows the telescope’s radiation shield to block light and heat from the Sun, Earth, and Moon at all times – vital for a telescope that does most of its “seeing” in infrared wavelengths.
JWST will be approximately 100x more powerful than the Hubble Space Telescope, largely because of a mirror that has about 6x the light-collecting area of Hubble’s primary mirror:
The Webb telescope also operates primarily in the infrared, which will let it peer farther away in space and further back in time (the light from more distant objects is shifted toward the infrared because of their relative motion away from us due to the expansion of the universe; we see more distant objects the way they were billions of years ago because their light takes so long to reach us). It’s estimated that the Webb should be able to see as far back as 250 million years after the Big Bang – right around the time of formation of the first stars!
Some of you may know that the Hubble was the largest payload launched by the Space Shuttle: it occupied the entire payload bay of the Shuttle. The Webb is larger, of course, and so has to be folded up to fit in the Ariane launch vehicle:
The launch vehicle is ESA’s Ariane 5 – a heavy lift rocket with the payload capacity to get the Webb telescope on its way to L2. (The Webb has its own rockets to make the necessary course corrections to actually get to L2 and establish itself in orbit around it. More info on the planned orbit are here.)
Ariane’s engines will burn for 26 minutes, after which the telescope will separate from the rocket’s second stage and continue the remainder of its journey on its own. It will take about 30 days to get to L2, and after 5 months of commissioning (testing, calibration, etc.), science operations will begin!
The official JWST site is here: https://www.jwst.nasa.gov/
A very good explainer is here: