Translator: Carina Crispim
Reviewer: Cihan Ekmekçi My love for the night sky
began a long time ago. I grew up in the tiny rural farming
town of Bee Branch, Arkansas. Official population: 63. I'm not kidding. But while my small hometown
might not have had much of a social scene, the night sky was breathtaking. I spent much of my childhood lying on blankets out in the field
behind my mom and dad's house and asking my parents
questions about the stars, about how the universe worked,
about what lies beyond what we can see. And my parents weren't scientists, and these were the days
before the Internet, but I remember one day, I asked my mom some outlandish
question about the universe, and she looked at me and she said: "I don't know the answer
to that question, but one day, you can figure it out." And that's really what set me on my path
to becoming an astronomer. And of course, I'm not alone
in my love for the night sky. For centuries, human beings
have been captivated by the night sky. A dark sky full of stars has always been a standing
invitation to ask big questions. And these questions go
beyond just being scientific questions. They're questions that get to the heart
of what it means to be a human being. Where do we come from? How did we get here? Are we alone? And there's so much
we can learn about astronomy, just from simply
looking up at the night sky. Our ancestors learned
about the way the world works from watching how the constellations
would appear and reappear over the course of the year. The very first astronomers noticed that some of the brightest
stars in the sky moved in a different way
than most of the stars, and of course, those turned out to be
planets in our solar system. At that time, it was assumed
that Earth, our fragile blue planet, was the center of it all; that all the other celestial bodies
revolved around the Earth. And then one day, a little over 400 years ago, Galileo took his telescope, which was originally intended
to watch ships coming over the horizon and pointed it to the sky, and everything changed. That simple act shifted the paradigm
of how we view the universe, and ultimately how we view ourselves. Of course, what Galileo discovered was that Jupiter had moons
that were orbiting around it. That means they weren't
orbiting around the Earth; that means the Earth wasn't
the center of the universe. Game changer. And since that time, of course, our telescopes have gotten
bigger and better. As an astronomer, I've been really lucky to have observed at some of the world's
biggest telescopes in Chile and Hawaii. We put our biggest
telescopes on the ground, on tall mountains, so that we can try to get
above the Earth's atmosphere, which serves to blur and obscure the celestial objects
that we're trying to look at. But even on the tallest mountains, we still have to deal with the atmosphere. Now, we've found really cool ways to counteract some of the blurring
effects of the Earth's atmosphere. But we still have to deal with the fact
that the atmosphere is there, and our Earth's atmosphere completely obstructs
some wavelengths of light completely. Now, that's good for life on Earth,
not so good for astronomers, who want to view their objects
in all the wavelengths of light. So what do we do? We put telescopes in space. And of course, of all the telescopes, the space telescopes, the Hubble Space Telescope
is the world's most famous. Hubble has now been in space
for a little over 26 years; it celebrates its 27-year
birthday this year. Hubble has become
so much more than a scientific tool; it's become an inspiration for the world. It's become a pop culture icon. You can find Hubble images
everywhere in TV and films, as music album art,
on the sides of U-Haul trucks. Ask anyone in the world
to name a telescope, and they're probably going to say Hubble. The beauty of Hubble's images
have captivated the world. But it's not really straightforward why that is. Why do we find beauty in Hubble's images? It's natural that we find beauty in images
like sunsets or oceans or mountains; those things are all part of our
everyday experience as human beings. But nebulae aren't. Why do we find these images beautiful? I'm not sure that I know
the answer to that question, but I think part of the reason might be that we know that on a deep level, that we're connected to the cosmos. We know that when
we look up at the heavens, that in a sense, we're looking
back at ourselves, back at our origins. The iron in our blood
and the calcium in your bones was literally forged inside of a star that ended its life
in grand fashion as a supernova. We're connected
viscerally to the universe. Hubble's images also transcend
languages and national borders; their beauty is universal. Hubble's images have also told us
that we're connected to each other. Of all these beautiful Hubble images that we've gotten over the past 27 years, if I had to pick a personal favorite, this would be it. This is the Hubble Ultra Deep Field. This image came out
when I was in graduate school, so that's another reason
it's special to me. I did a lot of my dissertation
research on this image. But for a bigger reason than just that, this image has changed the way
we understand the universe. So, you go outside tonight,
look up at the stars, every star that you see in the sky
is part of our home galaxy, the Milky Way. But for this image,
Hubble stared past the Milky Way into this tiny little dark piece of sky. So that's like looking
at the universe through a straw. If you held out your pinky finger,
you could cover up this image. And in this image,
Hubble sees 10,000 galaxies. Every single point of light in this image
except for just a few foreground stars is an individual galaxy
containing billions of stars. And so, just imagine,
take this little tiny patch of sky, multiply it by the huge number of times
you would need to fill up the entire sky. What Hubble has shown us is that there are hundreds
of billions of other galaxies outside of our Milky Way. Hubble has given us
the size of the universe. But as amazing as Hubble is, as wonderful as it's been, as much as it's taught us
over the past 27 years, there are some ways
that we've pushed Hubble to its limits. And in deep images like this,
like the Hubble Ultra Deep Field, at some point, we come to the edge
of what we can see. And so we need a new, different,
more powerful telescope that will help us see beyond that edge and learn amazing new things
about the universe. And so, at NASA, we are working
on the scientific successor to Hubble, the James Webb Space Telescope. This telescope is designed to answer
the biggest questions in astronomy today, those questions that Hubble
just can't quite get to. And I truly believe that the Webb telescope will be
a worthy successor to the Hubble. So, Webb is different
from Hubble in a few key ways, and the first is the size. So Webb is big, really big. Webb will be by far the biggest
telescope we've ever sent to space. Hubble's about the size of a school bus. Top to bottom, Webb stands
over three stories tall and is as wide as a tennis court. The second big difference
between Webb and Hubble is the place in space that Webb will be. Hubble orbits the Earth
about 350 miles up, relatively close. We're going to put Webb
out a million miles from Earth, that's about four times
further away than the moon. We put Webb in this part of space
so it can get really cold. And that leads to the third key
difference between Hubble and Webb, which is the type of light
that Webb will see. Hubble is primarily
a visible light telescope; it sees the universe primarily
in optical light that your eyes can see. Webb will see the universe
in a whole new light, an infrared light. Infrared light is just a little bit
more red than what your eyes can see, and Hubble has a little tiny bit
of capability in the near-infrared. And this image shows a tantalizing hint of what we might be able to see with Webb. So with all of these new technologies, we hope to learn a few
key things about the universe. The first thing we want to find is the very first galaxies
that were born after the big bang. Telescopes are time machines that literally allow us to see
objects as they were in the past. As we use our telescopes
to look at objects that are further away in space, the light from those objects takes time to travel through space
to reach our telescopes. And the further back we look in distance,
the further back we're looking in time. And so with Hubble, we've been able
to push back and see distant galaxies, but we have yet to see
the very first galaxies that were born after the big bang. So we're talking
about looking back in time, over 13 and a half billion years. We have computer simulations that show us what we think
that part of the universe might look like. But there are no telescopes
right now in space or on the ground that are powerful enough
to observe this part of the universe. And with Webb, we hope to see
these infant galaxies. Another big key goal of Webb
is to learn how galaxies grow over time. So we want to see
how those infant galaxies grow up to be the grown-up galaxies
that we see in the nearby universe today. So the distant galaxies are much different
than galaxies in the nearby universe, and how that whole process happens
is still a big mystery to astronomers. And so with Webb, we hope
to be able to learn a lot more about that process in a new way. The third key thing we want to learn
with Webb is about how stars are born. So stars are the building
blocks of galaxies, but there's a lot about their formation
that we just don't know. And that's because stars
are born inside dusty cocoons, and we can't see the sites
of the star formation, at least in visible light. Infrared light has
the really great property that it's able to peer through dust
to see the stars inside being born. And in addition to stars,
we plan to study planets; both planets within our solar system and planets outside our solar system - exoplanets. When I was a kid, we only knew of the planets
inside our own solar system. Now, today, thanks to telescopes
like NASA's Kepler telescope, we know that the universe
is literally teeming with planets. Go outside at night, point up at a star, and chances are there's at least
one planet orbiting that star. That's a complete paradigm shift. Kepler has shown us that these star and planet systems
come in an incredible variety, in combinations that
we had never imagined before. The Kepler telescope finds
these planets by staring at a star, watching for the light
in the star to dip down, which means a planet
has passed in front - a transit. So that's how Kepler
has found all these planets, but with Webb, we want
to go one step further. We want to watch the starlight
as it filters through the atmosphere and learn about the chemical
components of those atmospheres. We want to be able to find chemicals like water vapor, carbon dioxide, methane; the chemicals that would
signal habitability. Now, this is really, really hard,
and this image demonstrates why. This is an actual image,
from one of NASA's solar observatories, of the transit of Venus,
that happened a few years ago. Now, if you squint, you can almost see
the tiny little atmosphere that Venus has. Stars are bright, planets are tiny, and their atmospheres are minuscule. We need incredibly advanced technology to be able to look in detail
at these atmospheres, but with Webb, we have it. So even with all of that technology, we would really need a planet system
that was relatively nearby, had the planets that were
the right distance from the star, all the right things to line up to find
a potentially habitable planetary system. We require a lot of luck. But sometimes nature delivers. Just a few weeks ago, we got new observations
of the Trappist-1 planet system, which is a mere 40 light years away -
our cosmic backyard. These new observations tell us
that three of these seven planets likely lie in the habitable zone. We don't know anything
about these planets, we don't know if they have atmospheres
or if they would be hospitable to life, but with Webb, we intend to look. And the great news is
that after two decades of hard work, we are almost finished
building this incredible machine. The iconic gold mirrors
of the Webb telescope were on of the first technologies
that we started working on. The whole mirror put together
is about 21 feet wide, and it's coated in an incredibly
thin layer of gold, because gold is highly
reflective in infrared light. The mirrors are also incredibly precise. If you were to stretch out
that 21-foot mirror to be the size of the continental US, the biggest bumps and valleys
would only be a few inches. This is incredibly difficult engineering, and this is the first time a mirror
like this has ever been sent to space. Just last year, we finished
assembling this giant mirror. So much work has gone on
to get us to this place. The other iconic part of the telescope and the biggest structure
on the telescope is the giant sunshield. So this is a five layer sunshield that protects the mirrors
and the instruments from the light and the heat of the Sun. Of course, all these elements
require extensive testing, and testing has been going on for pretty much since the start
of the whole program. All elements are tested
at their individual levels and then as bigger systems. In fact, if you go to our website, on our homepage, you can watch
a live webcam of some of this testing going on right now at NASA's
Goddard Space Flight Center. In just a couple of months, we'll shift
the mirrors and the instruments down to Johnson Space Center, in Houston, where it will undergo
extreme cryogenic testing in the giant Chamber A, which is the chamber that was used
to test the Apollo era spacecraft. Old meets new, history meets the future. And oh, by the way, we have a really intricate
deployment sequence that we have to do with this telescope. So launch is only the beginning. Once it gets into space, it has to unfold, and this whole process
takes about two weeks. Now, today, we can take
Plato's words more literally. Today, right now, NASA is building
the rockets and the capsules that will take human beings to Mars. Today, we're dreaming
and building the telescopes, Webb and it's successors, that will ultimately find life
elsewhere than our pale blue dot. Astronomy and this deep drive to explore
is what drives us towards these missions. The reason we build these missions
is because of the promise of discovery. It's the promise of hundreds
of billions of planets in hundreds of billions of galaxies and countless untold surprises
waiting to be discovered. Thank you. (Applause)
