Good morning, John. Now, I would not normally release a video on Christmas Eve, but a bunch of people who have been working for decades on one of the most exciting scientific instruments ever built are going to be released that into space on Christmas Day, so I could not help myself.

I made a video about the James Webb Space Telescope and how it is going to be on this channel 10 years ago, and now it is headed to space. This is an endeavor to help answer real, deep, human questions, some of the biggest ones, like how do planets form? Is there life elsewhere in the universe? And how does the universe work?

But you can't do what the JWST wants to do from the ground, and to understand why, you have to remember that light is made up of lots of different frequencies. We can only see with our eyes a really narrow band of those frequencies, but the Webb wants to see specifically in infrared for several different reasons, the big one being that the universe is expanding, and so things that happened a long time ago and are very far away, their light has actually been stretched by the expansion of the universe, and it's been stretched into the infrared.

But there's a problem with this, which is that infrared radiation comes off of anything that has heat, and basically everything has heat, but the exceptional reality of the Webb is that, at the tiny, dim levels of light that they want to measure from exoplanets or the beginning of the universe, if the telescope itself is warm at all, the mirrors will radiate infrared light that would overwhelm the observations, so the telescope has to be extremely cold. So you need to block out all sources of heat, particularly the Sun, but also the Earth and the Moon, which shoot off enough infrared radiation to heat up the telescope too much.

So the telescope has to have a heat shield that can block all of that heat, but it needs all of those sources of heat to be in the same direction so the heat shield can block all of them at the same time. Luckily, there is a gravitationally stable point on the opposite side of the Sun-Earth system, and that is where the Webb will orbit, keeping its solar panels and sun shield pointed toward the Earth and the Sun, while on the other side, the telescope, thanks to its five giant heat shields, will be cold enough to liquefy air.

The launch and deployment of the JWST is going to be extremely tense. It's scheduled right now for Christmas morning, 7:20 Eastern Time, and that launch is gonna be tense, but it will not be the end of the tension. So just so you know what we're in for in the path to making these tremendously valuable observations, here are the biggest sighs of relief that we are going to experience over the next month.

The first one will come about 33 minutes after launch, when the solar panels will automatically deploy, because that means we are in space and the craft can power itself. 12 hours after launch, we have the first burn. Now, remember, the Webb cannot be refueled. It has all the propellant it will ever have, so depending on how accurate the initial launch was, this course correction could use more or less fuel, and using less could potentially add years to the mission, so another big reason to worry right here.

Three days after launch, you start the five-day-long process that is, to me, the scariest - the deployment of the Sun shield. Each of these tennis court-sized sheets are thinner than a human hair. Everything has to go right. It has been tested, and it all should. The temperature difference between one side of these sheets and the other side is 600 degrees Fahrenheit.

And finally, the biggest weight comes off of everyone's chests 13 days after launch when the mirrors and some other important bits of the telescope have been fully deployed, and it will be ready to be a telescope. And the final sigh of relief happens 29 days after launch when the telescope will be at a stable orbit at L2, at which point the Webb will have been successfully deployed, and the team will spend a further four to five months calibrating and testing the telescope before, five to size months after launch, we receive the first ever images from the James Webb Space Telescope.

John, I don't know what the point of being a human is, but I know that somewhere close to the root is curiosity. We wanna make the world better for ourselves and for other people, but even without that concern, I think we want to know. We wanna learn. We wanna look really deep into ourselves, into our world, and into our universe. And, in a very literal way, we are about to see deeper than we ever have before.

The JWST's launch is scheduled for Christmas morning, 7:20 AM Eastern Time. John, I'll see you on Tuesday.