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It's primed and full of fuel, the James Webb Space Telescope is ready to be packed up prior to launch

Fingers crossed the telescope will finally take to space on 22 December

Engineers have finished pumping the James Webb Space Telescope with fuel, and are now preparing to carefully place the folded instrument inside the top of a rocket, expected to blast off later this month.

“Propellant tanks were filled separately with 79.5 [liters] of dinitrogen tetroxide oxidiser and 159 [liters of] hydrazine,” the European Space Agency confirmed on Monday. “Oxidiser improves the burn efficiency of the hydrazine fuel.” The fuelling process took ten days and finished on 3 December.

All eyes are on the JWST as it enters the last leg of its journey to space; astronomers have been waiting for this moment since development for the world’s largest space telescope began in 1996.

The $10bn project is the most complex and ambitious attempt to launch an observatory beyond Earth yet. Measuring about the size of a tennis court, its 6.5-meter-long panel of 18 hexagonal gold-coated beryllium mirrors sits on top of a large sunshield. It’s bigger than NASA’s Hubble Space Telescope, and wider than the Ariane 5 rocket taking it to space. The whole thing will have to be neatly folded and packed away during launch.

Over the next few weeks, the teams behind the telescope and the rocket will work together to place the giant observatory inside its launch vehicle. It’ll then be carted away for final testing before it launches from the spaceport in French Guiana as soon as Wednesday, Dec 22, at 0720 EST.

Once it leaves terra firma to get to its final destination 1.5 million kilometres (930,000 miles) away, a region known as the Earth-Sun L2 Lagrange point, mission control will kickstart a series of steps to slowly unfurl the telescope bit by bit. Everything has to work perfectly, humans will not be able to service the JWST at that distance. It won’t be fully deployed until 30 days after launch, as the video below demonstrates.

Youtube Video

Unlike Hubble, the new telescope will observe light sources at wavelengths of 60 to 500 microns in the infrared spectrum. It’s large mirror means it'll be able to focus light at further distances and peer at the universe over 13.5-billion years ago, during a time when the first stars began to form, allowing astronomers to see wider and deeper into space than ever before. ®

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