James Webb Space Telescope to Launch Christmas Day (Maybe)

[Yazata]

It's a large 6.5 meter reflecting telescope, optimized for infrared viewing. This has astronomers all excited since the earth's atmosphere blocks out most infrared and there's no end of astronomically interesting things to look at in infrared, from red stars, to very distant high redshift objects, through all sorts of accretion disks, to brown dwarfs. Hubble has been doing what it can, but it isn't optimized for infrared.

I'm a little concerned about JWST, since it just looks fragile to me. Overly complicated. It has to fit in a rocket's payload fairing, then unfold like a complicated piece of origami. There's just one JWST, its cost is almost $10 billion and if it's lost or it doesn't deploy properly, there's no backup. They only have one shot at doing this.

It's destined to reside at the Earth's L-2 Lagrange point. This is on a straight line from the Sun through the Earth, about 900,000 miles further out from the Sun. Generally speaking, objects further from the Sun orbit the Sun more slowly. But at L-2, the additional gravity of the nearby Earth pulls objects around faster, so L-2 is a good station-keeping spot relative to the Earth and the Sun. A great spot for space telescopes. Relative to the telescope, both the Earth and the Sun will occupy the same unchanging place in the sky which can be blocked out with a big sunshade attached to the telescope, allowing it to cool down to near absolute zero so as to optimize its infrared optics. (Can't have the telescope glowing more brightly in infrared than what it is looking at.)

The JWST is a joint project of NASA, the European Space Agency and the Canadian Space Agency. The US designed and built JWST at NASA Goddard Space Flight Center, Northrop Grumman was prime contractor, the ESA will launch it and are providing several of its IR instruments. Canada is providing its fine guidance sensor and a spectrograph. It will be operated by the Space Telescope Science Institute, the same people who operate Hubble.

Launch will be at the European Space Agency's Guiana Space Center in Kourou French Guiana (in the South American jungle) atop an Ariane 5 rocket, the Europeans' current heavy lift rocket. (They are working on an Ariane 6.)

Launch window is Christmas day 4:20 to 4:52 AM PST, 7:20 to 7:52 AM EST, 9:20 to 9:52 Kourou time, 12:20-12:52 PM UTC, 1:20-1:52 PM Paris time, and 11:20 to 11:52 PM Christmas evening Australian Eastern Daylight Time for our Antipodean friends. It isn't entirely certain that the launch will get off then, since thunderstorms have been happening every day and are predicted for Christmas too. (It's the tropics.)

https://twitter.com/Arianespace/status/1...5185154053

It should be livestreamed by nasa tv

https://www.nasa.gov/nasalive

For you Francophones, Arianespace will be livestreaming it

https://www.spacetv.net/arianespace/

It will be livestreamed by nasaspaceflight.com as well (their own Chris Gebhardt flew down to remote French Guiana to set it up) but I don't have the URL yet. It should be on the nasaspaceflight youtube channel.

Chris Gebhardt of nasaspaceflight.com in Kourou, French Guiana in front of the huge French Ariane 5 rocket that will (hopefully) hurl the JWST out beyond the Moon's orbit to L2 Christmas morning.

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The elaborate unfolding process

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[Yazata]

The rocket has been rolled out to the pad at Kourou in preparation for tomorrow morning's launch. It travels from its assembly building to the pad on a huge Cape Canaveral style transporter. Except that this one travels on rails while the Cape Canaveral transporters (used with Saturn V, the Shuttles and now SLS) roll on giant tank treads.

Weather is not good. They will have a weather decision point 6 1/2 hours before launch when they have to decide whether to chill down the propellant lines prior to fueling. (If the lines aren't really cold, cryo propellant will boil when it flows through them. Much of the white vapor you see venting from rockets prior to launch has to do with this process.)

(Photos by Chris Gebhardt on the scene)

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View of the European Space Agency's Guiana Space Center from building where Chris attended a pre-launch press briefing. (In French?? Chris doesn't speak French as far as I know.) Chris Bergin fears that if the launch is delayed and Chris spends too much time in French Guiana, he may come back speaking French and cheering for French soccer clubs.

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From The Daily Hopper

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[Yazata]

Here's a great webpage that will help you track where JWST is on its long trip to L2 and how its unfolding and deployment is going, plus no end of great photographs and some videos.

https://jwst.nasa.gov/content/webbLaunch...sWebb.html

Jonathan McDowell has this chart showing all the steps before JWST is up and running. That will take six months!

https://planet4589.org/space/misc/webb/time.html

Livestream here

https://www.youtube-nocookie.com/embed/5rARTOhbLDg

[Yazata]

T - 30 minutes - "the board is green" - no problems so far

Edit - T - 10 minutes - everything 'go' - weather is green, board is green

Edit - It's off - successful launch so far

Edit - Successful staging - nominal trajectory - successful fairing separation

Edit - Second stage cutoff (SECO) - spacecraft separation. JWST is on its way to L-2 (which will take a month to reach). The Ariane did everything as planned. European Space Agency is happy.

JWST now has 300 plus unfolding steps which will also take a month.