can you give us a little refresher on
the big bang
sure the big bang a short refresher
let's see
just the beginning of everything yeah
beginning of everything no big deal
put these little glue dots on the back
of these
so now we're going to build the mirror
golden hexagons silver sunshield
keep putting it on backwards
i'm amber strawn an astrophysicist at
nasa and today we're going to be
building a model of the james webb space
telescope the largest most complex most
powerful telescope nasa has ever sent a
space
[Music]
this telescope has been in development
since 1996. bill clinton was president i
looked it up the top song on the radio
was the macarena
and that wasn't too far after the hubble
went up into orbit right so what was
inspiring the folks at nasa at the time
to start planning for another one so
soon we've been able to see very distant
galaxies with hubble but if you look in
these deep fields you see where you come
up to the edge where there are no more
galaxies but we know there are more
galaxies
we knew that in order to find extremely
distant galaxies we would need an
infrared telescope and jwst was
specifically designed to be able to see
that first epic of galaxies that were
born after the big bang
how does that work
yeah so we're basically able to do that
because
light takes time to travel across the
universe so you can sort of think of
you know the light from the sun takes
about eight minutes to get to the earth
so we're seeing the sun as it was eight
minutes ago like if the sun went out
right now would know for eight minutes
and then galaxies that are further away
the light from them takes
longer to get here so we're seeing them
as they were further in the past but
they very likely now have you know stars
and planets and evolved possibly you
know evolved life forms which is super
exciting maybe even life forms that
build telescopes who knows right they
could be they could be looking back at
us but of course they would be seeing us
as we were what would they see if they
were doing exactly the same thing that
we're doing they would basically see the
same thing that we're gonna see when we
look at them
which is like primitive galaxy exactly
so
basically not long after the big bang
the only thing in the universe was
hydrogen and helium but there were some
parts of the universe that were more
dense than other parts and that collapse
of that hydrogen and helium were
the first stars in the first galaxies
and so by looking at the different
galaxies at different distances we're
sort of able to put together a picture
of how galaxies change over time
okay so i'm gonna pop this on
slide this on this one
so this is where all the electronics
will be
and then here we have our solar array
which is where we get power and this is
a communications antenna so we can talk
to the spacecraft once it's in space
what are these
the telescope the mirror and the
instruments have to be shielded from the
light and the heat of the sun you know
you think of a normal telescope like
hubble or your backyard telescope and
those telescopes have tubes right that's
what shields those mirrors
this telescope since it's so big and
also since it's going to be very far
away in space we don't really need a
tube we only need a shield and the
mirrors and instruments will be able to
stay very very cold that is important
because this is an infrared telescope
and we have to use infrared light to see
those first stars and galaxies but
everything
above absolute zero glows in infrared so
you and i glow in infrared the planet
the sun you know everything is infrared
it's like thermal camera night vision
exactly yeah you can sort of think of
night vision goggles if it was warm it
would sort of glow and sort of see
itself so that's why we're putting it
out in deep space and that's why we need
these amazing sun shields
so where exactly in space will this
telescope live so we are sending this
telescope about four times further away
than the moon to give you a sense of
skill okay so hubble is like really
really close compared to that yeah and
hubble's going around us so it's getting
closer to the sun far away from the sun
right this thing is going to stay on our
night side
on the mars side of earth and just kind
of
head around the sun with us yes always
on the outside exactly yeah it will sort
of you can think of it it'll always be
sort of in the midnight sky
sort of straight above
so the sun shields are keeping the heat
away from the mirror and the instruments
how hot would it get if they weren't
there
so the sun is always you know shining on
this bottom side of the telescope and
this is about
200 degrees fahrenheit and the cold side
uh will end up being about 400 degrees
below zero fahrenheit so it's a it ends
up being about a 600 degree difference
between the hot side and the cold side
just because of these five little super
thin yeah how does that work so the
reason that there are these five layers
is because in between each layer the
heat basically is radiated outward okay
and so by the time you get to each
successive layer it's a little bit
cooler
and so that's the reason one sunshield
wouldn't work okay this design gives us
a more uh more efficient way to get it
very very cold on the top
okay so now we're going to build the
mirror
so if you want to put glue dots on the
back and then hand me the piece sure so
just to get back to the basics why do
telescopes have mirrors so mirrors are
essentially light buckets so the size of
a mirror is really important
because if you think about sitting a
bucket outside when it's raining the
bigger your bucket the more water you're
going to collect this mirror is about 21
and a half feet across it's about six
times the light collecting area of
hubble and in comparison to hubble of
course hubble is our gold standard of
telescopes and we love hubble we do
but when we take into account the size
of the mirror the wavelength range that
this telescope will see in the infrared
light and the sort of efficiency of the
detectors
we expect
this telescope to be about 100 times
more powerful than hubble that's crazy
it's gonna be awesome
and so why gold and why hexagons so gold
it turns out is a great reflector of
infrared light the reason it's in
hexagons is we can't launch it fully
deployed as a full mirror so we have to
fold it and hexagons pack together very
nicely and are very foldable
so
basically
these three mirrors and then these three
mirrors will fold backwards
and then once it gets to space it has to
do the opposite it has to unfold and
then we have a telescope
and how long does that process take that
whole process takes about two weeks from
start to finish so it's gonna be intense
two weeks after lunch and if something
doesn't happen exactly as it's supposed
to or exactly as we've planned we can
pause
figure out what's going on and then work
to fix it but fixing it does not include
sending an astronaut there to fix it
definitely not so it's going to be too
far away to send astronauts to you know
there is some risk involved in in
building a telescope like this we can't
go fix it and that's one of the reasons
it's taken so long to test it to make
sure
it's going to work like it's supposed to
[Music]
light travels across the universe hits
here then there's a secondary mirror
and it bounces off of that and then it
goes into here and then what happens and
then it collects on the instruments so
that's behind that's there this is an
international collaboration and yeah
europe is providing a couple of our
instruments and canada is providing an
instrument
so the
telescope has fuel
and i read that the fuel
can only last maybe up to 10 years
so
25 years of development
10 years of operation
can you explain why this is worth it so
if you consider the cost of this
telescope over development and
operations it actually comes out to be
less than the price of a cheap cup of
coffee
per year
per us citizen okay
so
one cup of coffee per person per year
yeah that's easy in a cheap cup like
less than a buck okay like a bodega
coffee yeah exactly i also think it's
sort of
like it's in the dna of our country that
we spend money on things that make the
world
more good things like
public parks and public libraries you
know those things that we sort of all
enjoy and that make the world a better
place and
i really think astronomy
falls into that category you know we
have this 13.8 billion year story of the
universe
and it's like we're missing
key paragraphs from that very first
chapter we don't know how it got started
and so that's one of the key things that
we're going to be able to do with this
telescope
and it's so cool to think that the light
that this is collecting
will have left the source
has been traveling for billions of years
yeah our solar system forms in the
meantime yeah an intelligent species
evolves
and creates this machine yes throws it
into space
and there is the light to meet it so
that we can figure out where we came
from
we have all these specific plans these
specific things we want to learn but i
think that
the most awesome thing we'll end up
learning with this telescope we haven't
even thought of yet
because when we increase our technology
by an extreme amount like this
i think it's inevitable that we'll find
something that completely surprises us
and causes us to rethink how we
understand the universe
[Music]
our model was based on a paper cutout
model that was designed by john joe
gerst it's available on nasa's website
and we'll put the link in the
description and if you want to learn
more about the web telescope the podcast
unexplainable did two incredible
episodes about it a few months back go
to your podcast app look for
unexplainable and check them out