Loren Grush:Say hello to NASA’s James Webb Space Telescope.
Well, part of it anyway.
But this is perhaps the most important part: a huge gold-coated mirror that spans over
21 feet.
It’s the actual telescope portion of this space telescope.
The optics -- or eyes -- if you will.
It’s what the telescope will use to gather light from the early Universe, allowing us
to see deeper into space and further back in time than we’ve ever seen before.
So far back, in fact, we’ll be able to see the stars and galaxies that formed just after
the Big Bang.
That’s because when it launches, the James Webb will be the most powerful space telescope
ever created.
Compare it to the Hubble Space Telescope, which has been taking spectacular images from
orbit for the past 20 plus years.
Well this new telescope is a whole lot bigger.
Its mirror has 7 times the collecting area of Hubble’s mirror.
And, James Webb is going to live much farther out in space.
One million miles from Earth, in fact.
It’s from this deep outpost that James Webb will see the Universe when it was just a newborn.
Light from the oldest, most distant objects takes…. a while… to reach us.
And the Universe is thought to be 13.7 billion years old, so the light from the first forming
galaxies and stars has crossed over 13 billion light years of space to get here.
So the farther out we look, the further back in time we can see.
But James Webb won’t be looking for visible light from these objects.
Instead, it’ll be looking in the infrared.
It’s a type of light we can’t see but can feel as heat.
It all has to do with our ever expanding Universe.
The earliest objects are moving away from us relatively quickly, and this movement extends
the wavelengths of their light toward the red end of the spectrum.
It’s a concept known as red shift, and the farthest galaxies have been “red shifted”
into the infrared.
And this light is super hard to pick up.
You see, everything that’s warm emits infrared light, so you can’t have a telescope like
this one on Earth.
It’ll just pick up the infrared light in our atmosphere and from our planet.
Even the telescope itself emits too much heat.
That’s why James Webb is going super far out into space, where it can be kept at a
frigid temperature of less than fifty degrees above absolute zero.
That’s minus three hundred and seventy degrees Fahrenheit.
In order to pick up this infrared light, that’s where James Webb’s mirror comes in.
It’s made up of eighteen hexagons of beryllium, all of which are coated in a thin layer of
gold that’s just one-thousandth the thickness of a human hair.
The gold is what makes it easier to see in the infrared.
Those mirrors will then reflect light onto a secondary mirror, extended out in front
of the telescope.
That mirror will funnel light into the telescope’s instruments on the backside of the mirror.
And it’s these instruments that will give us the juicy details about the early days
of the Universe, as well as see things sharper than any telescope has before.
John Mather: If you were a bumble bee, hovering out at the distance of the moon, we would
be able to see you.
Both by your reflected sunlight and by the thermal radiation, the heat that you emit.
Loren: But there’s still a long journey ahead before that can happen, and NASA has
already been working on the James Webb for two decades now.
Its development has been hampered by delays and budget problems.
The telescope was expected to cost somewhere between one and three point five billion dollars
with a launch somewhere between 2007 and 2011.
But its budget continued to grow by billions, and its launch date kept getting delayed.
That caused NASA to do a “replan” of the entire project in 2011.
Now the James Webb project is expected to cost eight point eight billion dollars, with
a projected launch in October 2018.
NASA says the telescope is finally on budget and on schedule for that launch.
But there’s still a lot of testing that needs to be done.
The telescope portion of James Webb has to go through vibrational and acoustic testing
at NASA’s Goddard Space Flight Center, to see if it can handle its launch into space.
It’ll then head to Johnson Space Center in Houston to go through cryogenic testing,
to see if it can handle those super freezing cold temperatures.
And after that it’s off to California where the telescope will meet up with its sunshield
— five layers of a material called Kapton that are roughly the size of a tennis court.
This shield will help protect James Webb from too much heating by the Sun.
After some more testing there, the telescope will be ready to fly.
It’ll be loaded on a ship bound for French Guiana in South America — where the telescope
is set to launch on top of an Ariane 5 rocket.
But once James Webb launches, the anxiety is FAR from over.
The telescope is so big that it has to be folded up during launch.
And when it gets to space, it has perhaps the most complicated deployment process a
satellite has ever had to pull off.
Here’s what that process looks like.
We’ll...uh speed it up for you.
If one of these steps goes wrong, it could spell bad news for the rest of the mission.
And once James Webb is out there, that’s it.
We can’t really visit the spacecraft.
When Hubble needed upgrading, astronauts could just go into lower Earth orbit to fix it,
but James Webb will be so far out into space that taking a trip to the telescope is basically
out of the question.
There used to be talk of attaching a grapple fixture to the telescope.
It’s a bar that future crewed or robotic spacecraft could latch onto, in case we ever
wanted to visit James Webb.
But that grapple was never added, which means the telescope will be all alone out there.
But if this actually works, we’re going to see a part of our Universe we’ve never
seen before.
And it’s not just the earliest stars we can see.
We’ll also be able to see planets that orbit around distant stars.
So not only will we find out more about our Universe evolved, but maybe even get closer
to answering if we’re alone here too.
Loren making weird noises