(upbeat piano music)
- [Buell] The Giant Magellan Telescope or GMT
is a telescope with seven
8.4 meter primary mirrors
that will be connected
and supported together to work
as one giant 24.5 meter in diameter mirror.
That is 10 times larger than the Hubble Space Telescope.
And we'll see details 10 times sharper.
We've completed the fabrication of two
of the seven mirrors that we need
for the primary mirror of GMT.
We're working on the third, fourth,
and fifth at various stages of manufacture.
And we just cast, just started making the sixth mirror.
The seventh mirror will be cast in two years.
We're hoping to see for light in 2029.
(electric door buzzing)
(electric door buzzing) (metal screeching)
- [Buddy] Well, the Richard F Caris Mirror Lab
is unique in several ways.
Most obvious is that we do make
the biggest mirrors in the world.
More important than that,
they're the only big lightweight mirrors.
So they're the only mirrors
that have the ideal mechanical
and thermal properties to hold their shape accurately
in the telescope.
I came into this job in an uncommon way.
I started out as an astronomer when I was young
a professional astronomer,
but I was finding that I was more interested
in building equipment than studying stars and galaxies.
Fortunately, I had the opportunity to meet Roger Angel.
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Roger work in mostly with John Hill,
developed the methods of melting the glass
to form this lightweight structures.
They started working on this around 1980,
but by 1983, they had settled on the method
that's almost identical to what we're still using today.
(emotional guitar music)
- So, I got my PhD here at the university of Arizona
and I arrived in the fall of 1984,
shortly after Roger and John
had started developing the techniques
that would lead to the spin-cast mirrors.
I still remember going and roasting marshmallows
off of one of those early furnaces.
And while that was going on,
the plants were being made to build the Mirror Lab
under the stands of Arizona stadium.
And then that was completed just a few years later.
- [Stuart] Yeah, Roger Angel's vision was at bigger
and bigger mirrors.
So we needed more space.
And that's where this started way back in the late 80s.
The real estate here was available
and it started as one hall
and it is now three halls.
Is a, we now have a casting hall, polishing hall,
and integration hall.
And that's what it takes to fabricate multiple
8.4 meter mirrors.
(engine humming)
- So, it takes us roughly four years to make a mirror.
And about the first year of that is
the whole casting process
including building the mold
and the long cooling that has to go on.
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We actually do spend four months
building this mold that is filled with
1700 hexagonal boxes.
And when the glass melts and flows around those boxes,
that'll form the cavities in the honeycomb.
The glass is piled on top of it.
We receive it in chunks.
We buy it from the Japanese company, Ohara
and they have a process that is perfect for our needs.
They melt the glass in one ton clay pots
and then break it carefully into chunks.
We'll pile those carefully on top of the mold
then enclose it in the furnace,
heated over about five days.
And at that point, the glass, it doesn't get very runny.
It has a consistency like molasses.
The atoms will finally get locked in place
at about 500 degrees C.
That gives you the structure that you need for a mirror.
It's got the ideal
mechanical and thermal properties
but it doesn't have an accurate optical surface yet.
The final three years are grinding and polishing
and that's almost all about achieving the accurate surface.
And it's the polishing process
that will eventually produce this surface.
It's accurate to a millionth of an inch.
As we're analyzing the structural processes,
we always have to be very aware
of the stresses that are put into the glass.
There's always a concern about stress
because glass is a fragile material.
We all know that.
- [Buell] There's a reason why everyone
at the Mirror Lab is fairly conservative
in how you handle the mirrors
and how you get the final figure that you want.
The current manager of operations, Stuart Weinberger
has done a particularly impressive job
over the last year during the pandemic.
- The first challenge was just getting back into the lab.
So we sent everybody home back in mid-March
and then we had to come up with a plan
to describe how was it we could perform operations
in a safe manner.
Now, fortunately, these halls are very large
so it's fairly easy to keep people separated.
So we only brought in those people that had to work.
Most of our scientists and engineers,
they operate from home
and that's still occurs to this day.
Keep the personnel density down
and we keep people safe.
- Now the Mirror Lab is at its heart,
the people, the talented women and men
that use their science, their engineering,
and their artistry to make truly remarkable
and unique optics for telescopes.
- The real motivation
for everything we're doing
and I feel this
is to enable the amazing science
the stunning discoveries that are someday gonna be made.
I mean, it's happened every time.
There's a big increase in the size of a telescope.
(calming music)
One of these days, these mirrors are gonna be
in the world's largest telescope,
and they're gonna be discovering things
that could not be seen with any previous telescope.
- Roger and John started 40 years ago.
It's going to take us another 10 years to finish it.
And the young women and men that will actually use it
to look for life on planets around other stars
are probably in their twenties right now.
So it really is our equivalent of modern cathedral building.
We're all looking to the future
and dreaming about what
subsequent generations are going to learn with our efforts
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