This is currently the worldâs largest optical
lens ever built. Measuring 1.55 meters in diameter, this piece of glass is one of three
lenses that will be the eyes for a new astronomical camera. It weighs over 3 tons and has an
enormous field of view, where light from billions of galaxies will come into focus. With decades
in the making, this camera will be mounted on a telescope in Chile to construct a time-lapse
of the universe. Every 30 seconds we're going to take a new picture of a different piece
of the sky, and we're going to keep doing that every night for 10 years. A single picture
is 3.2 billion pixels. We're taking a movie and making that available to anyone who wants
to do science with it. It's a fantastic opportunity to be living in a time where not only we have
these profound questions of the universe, but also we are building experiments that
are capable of answering them. One thing that is particularly fascinating about the universe is, in a way, how little of it we understand at this point. Right now, we live in a really
strange situation where we have a model of our universe that's simple but weird. We just
made up these components of the universe to fit our data, and they kind of work but we
don't really understand them. Itâs those two elusive puzzles in cosmology: dark matter
and dark energy. They greatly affect how the universe evolves over time, how the universe
expands over time, and how structures like galaxies or clusters of galaxies form inside
the universe. Astronomy used to be a science where a single scientist with a telescope
could make a difference. But, we're probably now at a point where that's no longer feasible,
where the resources you need to really find out something new are so large that you can
only afford them as a whole humanity. Unsolved Unsolved mysteries and international collaboration
are driving this current era of super scopes. Theyâre massive projects that take decades
of planning and technical innovation to bring online. Each has a unique design pointed towards
ambitious science goals, like imaging the galactic center and peering back to cosmic
dawn. This camera-telescope project will conduct the Legacy Survey of Space and Time , with
the Vera C. Rubin Observatory, named after an astronomer who found more evidence of the
universeâs fundamental weirdness. She discovered, using observation of the rotation of galaxies,
that there was much more material in them than we could see. That, together with lots
of other observations, led us to now be very certain that there's this other type of material
in the universe that we call dark matter. What you need to do is you need to collect
the light of many, many galaxies so you can tell the small effects that dark energy
and dark matter have on the light of those galaxies. There was a desire to have a telescope
that could observe the whole sky every few days. That means it's operating just as a
sort of a machine, just going click, click, click across the whole sky. It looks like
a searchlight It's very short and squat but that actually helps keep the moment of inertia
down and make it so you can actually move fast. There are three mirrors in the telescope
that collect the light from ancient photons that then get focused to three lenses in the camera. At the heart of the camera is the focal plane,
where light gets recorded into an image. The biggest feature of this camera is just how
large of an area of the sky it can take a picture of in a single shot. The area that
we can take a sharp image of with this camera in a single exposure is about 40 times the
size of the full moon. If you want to have that big of a field of view, that means that
the size of the focal plane is 0.6 meters in diameter. There's no detector that's that
big. You're going to have to make a mosaic. And you're going to have to tile that focal
plane with those detectors just like you would tile a bathroom floor. CCDs were chosen for
this. CCD stands for charge-coupled device; itâs a type of imaging sensor. CCDs were
first developed in the 1970s. And the idea is pretty simple. You want to take advantage
of the fact with silicon as a semiconductor, that if you shine light on it you can generate
a signal. The CCD is a set of pixels. In this particular system there's 189 science
CCDs and we want to tile this whole focal plane. Well we can't just slap them on there.
We need to come up with some modularity So it was chosen to package them in sets of nine.
So each set of nine CCDs was dubbed with the name raft. Each raft is a self-contained,
144 million pixel camera. Each of these raft tower modules gets mounted into a thing that's
called the grid. When you have a complex optical system and you go to focus the light
on this focal plane. Different wavelengths of light could focus at different places. The
universe is expanding. And so the further away you go, the spectrum of the object is
shifted towards the red. As the light comes through the atmosphere, it's going to bend
a little bit, and the red light bends differently than the blue light. If you had no filter
and you tried to just image with the whole visible spectrum it would blur the image because
the blue light and the red light would focus at slightly different positions. We've taken
the visible spectrum and we split it up into five parts. So the camera holds five filters. That color information is very important to be able to tell how far away the galaxy is
from us how old the universe is at the point we observe the galaxy. With a project this
jam packed with electronics, another component they have to build is a cooling or cryostat
system. Because heat can turn into unwanted noise. Systematic distortions caused by the
optics or the atmosphere trick you and make you think that the universe is doing something. Some
of the most interesting things we're taking pictures of are the faintest ones, and they
look like little smudges. The lower you can make your noise, the dimmer
you can properly measure. So we're integrating all these pieces.
The camera body's coming together, the cryostat's coming together And if we didn't have a pandemic,
I think we would have been scheduled to bolt them together by now. It'll get shipped to
Chile, and then it'll get transported up the mountain, and then we will assemble it on
the floor of the observatory, and we'll operate it there before it gets put in the telescope. There's
been an enormous number of people that have just poured their hearts into this thing,
and it's been a long time. And so I hope that we can make it work. The targeted operational
date is 2022 for this world class sky survey. And when the shutter opens, itâll take..
a deep, sharp, picture over a large, large area, and keep repeating that process, keep
taking new pictures of the same part of the sky. If you just imagine itâs 3 billion
pixels every 30 seconds, thatâs a thousand giant photos every night, for 10 years. You
end up with hundreds of petabytes of data. On the mountain, we're going to have a facility
so that we can look at the images right away and we'll do some really basic diagnostics.
It should be 30 seconds or so after an image comes out. Then the data goes down the mountain.
The processing and the storage and the analysis of that data is going to happen throughout the
world, in Chile, in the U.S., in Europe, and in Asia. We often have to develop completely
new ways of analyzing that data, just because it is this huge amount and we need to analyze
it very quickly. We also need to analyze it very accurately. Often times, artificial
intelligence is a key to doing that. We cannot afford to make even tiny mistakes just because
it is so powerful a data set that we would be overwhelmed by our little uncertainties. There's
a number of different things that you can do with this sort of data that are unprecedented.
We will see galaxy clusters forming, we will see supernovae going off in unprecedented
numbers, and we can use that information to find out what dark energy is doing to drive
the expansion of the universe. We will find a million things that go bump in the night
and they will be transmitted to astronomers throughout the world. All those alerts then
will be immediately available on the internet you can subscribe to them.Then maybe it wakes
you up and you run outside and open up and turn on your telescope. We're really building
this experiment, as scientists always are, to prove ourselves wrong, to find something
we didn't expect. But how do you find something you didn't expect? You have to be really careful. The
smoking gun in physics can be really small. It can be just that your data looks a little
bit different than you thought and there's no way of explaining that other than to change
your full understanding of the physics of the cosmos. We could find that there is a
little, just a little, less structure, there's just fewer clusters of galaxies in the universe
today than we would have thought. And that would already mean that we got the whole picture
wrong, there's really something fundamental missing. And so that's what I think could
happen, but who am I to predict that? So what I'm really hoping we will find here is that
that model is wrong, that it doesn't explain some of the observations that we're making,
and that that will give us a hint to what really is happening in the universe.
sda