This is currently the world’s 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. It’s 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.
They’re 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 universe’s 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;
it’s 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, it’ll 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 it’s 3 billion pixels every 30 seconds, that’s 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.