>> From the Library of
Congress in Washington DC. >> Stephanie Marcus:
Welcome to our first program of the NASA Series in 2018. We are in our 12th season. So were pretty excited about
that, and we're just going to keep on going as long as
NASA has things to tell us, and they never run out. So we have seven lectures
planned this year, and you can always check our
website for the upcoming ones. We'll have one in
April, late April. I have no idea what it is, but
anyway, I'm Stephanie Marcus from the Science, Technology,
and Business Division, and with Shawn, who
is out at the table, we coordinate this series. Our first speaker,
Jonathan Gardner, from NASA Goddard is the
perfect person to talk to us about space telescopes. He's been involved with them
since his undergraduate days. When he was at Harvard, he spent
a couple of summers working on a camera for the
Spitzer space telescope, and then he went on
to do graduate studies at the University of Hawaii,
which ain't all that bad. We wish we were there today, and then he had a
fellowship in England. So after that, he came back
to NASA and did some work on the camera for the Hubble,
which was placed on the Hubble, and he has been involved
with the James Webb telescope since its early days, and now, he is the Deputy Senior Project
Scientist for the James Webb. So without further ado, let's
welcome him, and we'll go through a lot of history and the
future of the space telescopes. Thank you. [ Applause ] >> Jonathan Gardner: Thank you. I'm going to tell you a story. It's one of the biggest
stories there is. It started 13.8 billion
years ago with the Big Bang. The initial formation of
all of the matter, energy, and structure that
makes up the universe. The Big Bang started out
very hot and very dense, but it was not perfectly
uniform. There were some places
in the universe that were slightly hotter and
slightly denser than others, and those places started to
build up over time, get larger and larger through the forces of
gravity, to form the first stars and galaxies in the
early universe. Those galaxies merged together
to become the largest spiral and elliptical galaxies
that we see today, and one of those galaxies
is our own Milky Way. Within the galaxies and within
our Milky Way, stars continue to form with their planets,
their planetary systems, and in some of those
planetary systems, there are small,
the rocky planets. At least one that we know of
has liquid water on the surface. That planet has life
and intelligence. So how do we know all this? Well, starting just
over 400 years ago, Galileo first took a telescope
and pointed it at the sky, and he discovered that the
moon has mountains on it. He found that Venus has phases
like our moon, and he found that Jupiter has
moons of its own. All of this lent support
to the theory of Copernicus that we are not actually at
the center of our universe but are in a typical place. His -- Galileo's telescope
gave him a factor of about 60 in ability to observe the
sky over the human eye. William Herschel,
about 150 years later, used a 49-inch-diameter
telescope, much more sophisticated than
Galileo's hand-held telescope, and he discovered
the planet Uranus. He discovered moons in the outer
solar system, and he mapped the, what he called, the
spiral nebulae. His telescope, 49 inches in
diameter, gave him a factor of 500 in observing power
over Galileo's telescope. Edwin Hubble, the
astronomer, not the telescope, was working in the early
part of the 20th century, and he had a 100-inch telescope
on Mount Wilson in California, and Hubble's telescope had
an additional advantage over Herschel and Galileo. The new science of photography
allowed him to store up light over time and take longer
exposures than simply looking through the eyepiece
of the telescope. That also allowed him to show
the results that he was getting to other scientists, who
were not at the telescope, and using this telescope, Hubble further studied the
spiral nebulae and was able to measure distances to
these nebulae and determined that they were galaxies
like our Milky Way but outside of our Milky Way. In this way, Hubble essentially
discovered the universe as we know it today. He also was able to measure both
the distances and the velocities of these galaxies and
found that everything in the universe is moving
away from everything else. In this way, he found that the
universe is expanding over time, and if you kind of roll the
camera backwards in time, you see that that leads you to
a beginning to the universe, which we now call the Big Bang. Hubble's telescope and photography gave him
an additional factor of 30 over Herschel's telescope. In 1990, we launched the Hubble
space telescope into space, and over the last 25 years,
we have sent astronauts up five times to
upgrade the cameras and to fix anything
that went wrong. By putting the telescope into
space above the atmosphere, we were able to get
a factor of 10,000, and that factor also includes
advanced electronic detectors, just like you have in
your phone right now. These advanced detectors
give much more sensitivity over the techniques
of photography. So if you asked the question
how you win at astronomy, well, this is a logarithmic plot
of these factors over time, starting with Galileo's factor
of 60 over the human eye, going up to William
Herschel's 49-inch telescope, and here we start to
bring in photography and then charge-coupled
devices, electronic detectors, and then the launch of
the Hubble space telescope into orbit at the end
of the 20th century. So the Hubble space telescope
with its factor of 10,000 over Hubble's telescope,
combined with 8 to 10 meter diameter telescopes
on the ground and the power of supercomputers to do theoretical modeling
have all led to a revolution in astronomy over the
last 25 years or so. So when you talk to astronomers,
they use three words. We now know. And the reason that astronomers
now will say we now know, instead of just we know, it's
because most of us working in the field can remember when
we didn't know these things. When I was in graduate school, we didn't have proof
of the Big Bang. We didn't know the
age of the universe. We didn't know about dark
matter and dark energy. We had not detected
gravitational waves, although they were predicted. We didn't know of any planets
around other stars, even though, again, we were expecting them. The outer solar system
had not been mapped, and there was no evidence
for water on Mars, or at least not liquid
water on Mars. So these are all things that
have been discovered since I was in graduate school in the
1980s, and I'm going to take you through a few of
these discoveries, sort of a greatest hits
of space telescopes over the last 20-25 years. So one of the important
discoveries about the universe is that
95% of the mass and energy in the universe is not
on the periodic table, and this was discovered 20 years
ago in 1998 using supernovae, a kind of exploding star, as a way of getting
distances to faraway galaxies. There are several
kinds of supernovae, but one in particular happens
when a white dwarf star, a star about the size of
the earth, a collapsed star, is accreting material
from a companion star. So gas from a companion star
in a binary system is falling onto the white dwarf, and it
keeps accreting more material until it reaches
a critical mass. That is the mass at which
it can no longer hold itself up against gravity. White dwarf stars are held
up by electrons and protons, and if you squish the electrons
and protons together enough, they turn into neutrons. A neutron star is the size
of the District of Columbia, about 10 miles in diameter. So this star goes from the size
of the earth down to the size of DC and releases a
huge amount of energy as a big explosion,
a big flash of light. But the interesting thing
about this type of supernova is that it always happens
at the same mass. It keeps accreting material until it reaches this
critical mass at which, and then it explodes, and then because it's always the
same size when it explodes, it always ends up to be
about the same brightness with the explosion,
and by looking at how bright the
explosion appears to us, and we know how bright
it actually is, that gives us the distance
to these supernovae. And they're bright enough, they
outshine, for a few days anyway, they outshine every other
star in their galaxy, and we can see these
to great distances. So 20 years ago, in 1998, astronomers mapping
the expansion history of the universe found that
the expansion was accelerating and not as expected
decelerating, slowing down, due to gravity. That led astronomers to propose
that there was a dark energy that filled the spaces
between galaxies that's pushing on the expansion and
causing the expansion of the universe to accelerate. Along with dark matter, which is
material that is not electrons, protons, and neutrons, but is
some sort of exotic material, that means that 95% of
the mass and the energy in the universe is not actually
normal matter that makes up gas, stars, galaxies,
planets, people, etc. Gravitational waves,
ripples in the space-time that make up the universe, were
predicted by Einstein's theory, but they are, although they
carry a large amount of energy, they are so tenuous that they're
very, very difficult to detect, but just about almost
2 years ago, the LIGO experiment first
detected the gravitational waves from a pair of merging
black holes. So into black holes
collide, they merge together, and there's so much energy that
it puts out gravitational waves. A bit less than a year ago,
the LIGO experiment combined with a similar gravitational
wave telescope in Europe, detected the merging
of two neutron stars, and these two neutron stars,
when they merge together, they put out a lot of light,
which was then detected by our space telescopes, by
the Hubble space telescope, the Fermi gamma ray
telescope, and so forth. This was the dawn of what we
call multi-messenger astronomy. Previously, astronomers
only used light, the electromagnetic spectrum. Light waves are waves seen in
electric and magnetic fields. We now have an additional
technique that we can use, gravitational waves in the
very structure of space time. Extrasolar planets were
first discovered -- normal extrasolar planets
were first discovered in 1995, and over the past 20 years, we
have found several thousand, including with space telescopes, and one of the very powerful
techniques that we could use to study these planets is
with the planet transits across the face of its
host star, and basically, that just means when
they line up. So the planet goes between
the star and our telescope. And so, light from the star
will go through the atmosphere of the planet, be
changed a little bit, and our telescopes can
detect those changes and measure the constituents
of the atmospheres of these extrasolar planets. A very exciting technique
that will get to be more exciting
in the time to come. So about two years ago, there
was a discovery of a system of seven rocky planets, all
transiting their host star, and this system is
one of the best cases that we have right now for
studying the atmospheres of these planets and looking
for things like do any of them actually have liquid
water on their surface? Do they have things like
oxygen in the atmosphere? Our outer solar system, when
I was in graduate school, consisted of Pluto, which we
called planet at that time. Since then, we discovered
what's called the Kuiper Belt, which is a large number
of small, rocky bodies, rocky or ice planets, that
we now call dwarf planets, of which Pluto is
just one example. That decision to call these
dwarf planets was made with the discovery of Eris,
which is actually larger than Pluto, and that triggered
the political discussion of what we call them. Didn't change what Pluto is. It's just what we call it. And the outer solar
system is the repository of the pristine material
that formed our solar system. So by studying these bodies
out there, these dwarf planets out there, we can
determine how our -- how the planets in our
solar system formed. And the ongoing exploration
of Mars has shown that while it's been
known for a long time that Mars has frozen
water on its surface, we now have evidence that there
was liquid water is recently as 50,000 years ago, which isn't that long ago in
geological time. So the surface of Mars,
at times in the past, could well have had oceans and
lakes, and we have some tenuous, ambiguous evidence that
possibly there are things like mudslides currently
happening on Mars. So one of the very interesting
questions that we would like to study is how
did galaxies form in the early universe,
the first stars and galaxies formed
after the Big Bang? And the technique that
we've used with Hubble to study early galaxies and the
early history of the universe is to take a picture, and this
is the faintest picture that humankind has ever made. We took Hubble, and
we pointed it at what is essentially a blank
part of the sky and just stored up the light over hundreds of
hours, a bit more than a month, and then, follow up have brought
the total investment of time into this image is
now approaching a year of Hubble time. In this image, almost everything
you see is a galaxy outside of our own. There are only about
a little bit less than half a dozen stars. So everything else you see in
the image is a distant galaxy. And some of those galaxies
are relatively nearby, with light that are -- the light from those galaxies have been
traveling through over time to get to us, and so, as we look
at galaxies that are further and further away, we're seeing
light that was emitted a longer and longer a time ago, and some
of them, the fairly bigger ones, are about a billion light-years
away, but some of the galaxies in the picture, the very
faintest ones, can be as much as -- will have emitted
their light at less than a billion years
after the Big Bang. So we're looking back almost
13 billion years in time over the history of the
universe when we look at these very faint,
distant galaxies. And this is -- the
biggest investment of time with the Hubble space telescope
was in this experiment, looking for the very early
history of the universe. And one of the interesting
things that we found was that when we study these very
distant galaxies in detail, some of them are actually
several hundred million years old. So this is several
hundred million years old at just 1 billion years
after the Big Bang. And this is the faintest
that Hubble can go. So if we want to go
further back in time, we need to find galaxies
that are even more distant, and catch them at the point
where they are first starting to form, first starting
to form their stars. This has led us to decide that we need a --
oops, just a minute. That we need a telescope
that is bigger than Hubble that can collect more light
and see more fainter galaxies, more distant galaxies. But there's another aspect of
these very distant galaxies, and that is, as the light is
traveling from the galaxy to us, through the expanding
universe, the light is stretched out by the expansion of
the universe over time, so that light that is
emitted as visible light or ultraviolet light has been
stretched out so that it appears to us in the infrared. Infrared light was discovered
by William Herschel, as well, when he took sunlight,
broke it up with a prism, and showed that a thermometer
here beyond the red would start to heat up. Infrared light is just
like visible light, but with longer wavelengths,
but it's also what happens when you've got -- when
something is at a temperature, it's got a temperature
associated with it. Now most of the sun's energy
that reaches the surface of the earth as visible light. That's not a coincidence. We evolved to be able to see
the light from our primary star. But infrared is heat, and here
are a few infrared pictures. First of all, there's a picture
of a man holding a lit match. So the brightest part of this
infrared picture is the flame of the match. The coolest part is the tie,
which is away from his body he, and his glasses, which again,
are cooler than his face. This is an infrared picture of a
cat, and again, the coolest part of the picture is the cats fur. It's a good insulator, but the
eyes and the mouth are close to the inside of the cat's body. So they're the warmest parts,
brightest in the infrared. You might be wondering what
the third picture is down here. Well, this is actually visible
light picture of a floor where somebody used to be
standing, but they walked away, but when we look
in infrared light, we see that the person's
feet has heated up the floor, left infrared picture behind. So, in order to see these
very distant galaxies that the first galaxies to
form in the early universe, we not only need a telescope
that is bigger than Hubble, but we also need a telescope
that can work in the infrared. So going back to how we
win at astronomy, well, the answer is big telescopes
with sensitive detectors in space, and that has led us to build the James
Webb space telescope, providing an additional factor
of 100 over the capabilities of the Hubble space telescope. Webb is the successor to Hubble. Successor is not
the replacement. We'd love to have them
both working together, and it looks like
we can do that. But the James Webb space
telescope will be a large, cold telescope in space, and
I'll be telling you about that in the rest of this talk. So the first science
idea we had for this, for what should be the
successor to Hubble, was to find the first
galaxies that formed in the early universe. That's what we call
the study of origins, because beginnings
are very important when you have the
way something starts out can tell you the initial
conditions for changes over time, but in things
that are complex, like babies and galaxies, studying
those actual changes over time are also
very important, and that's what we
call evolution. So the science of web is the
beginnings, or the origins, in evolution of galaxies. So pictures like the
Hubble ultradeep field, we will do with the James Webb
space telescope going fainter and into the infrared, to find
the first galaxies that formed in the early universe. We will then trace
those galaxies over time to see the formation of the
spiral and elliptical galaxies that we see today, spiral
galaxies like our own Milky Way. It turns out that a large
infrared telescope is also very good at studying the formation
of stars within our own galaxy. So that's what we have here. Stars form in clouds of gas
and dust, and when stars form, they also form planets,
and the study of planets, both around other stars and
planets in our own solar system, can tell us about the conditions
that might make it possible for life to develop
on those planets. So going through
these one by one, looking at supercomputer
simulations, this is a simulation of the
formation of the first galaxies. The universe started
very dense and very hot, but in some places, it
was slightly more dense, and in those over-dense places,
the material started to fall in, both dark matter and then,
eventually, the ordinary gas of the hydrogen and
helium that was formed in the Big Bang started
to fall in. Eventually, those clouds of
gas formed the first stars, and that's what we call
the first galaxies. They started out, actually,
fairly small, and then built up over time as galaxies
merged together. Many galaxies today
live in groups. This group of four galaxies,
and you can see the difference between the spiral galaxies and
elliptical galaxy down here. In these groups of galaxies, or
in bigger clusters of galaxies, galaxies do collide
with each other, and when two large galaxies
collide, they don't collide in the way that cars collide. They don't go bang. They kind of go slosh,
because most of the space in a galaxy is empty space. The stars that make up
the galaxy are very small in comparison to the distances
between the stars, and so, two colliding spiral galaxies, as you see in this
supercomputer simulations, will slosh together,
interacting through gravity. The gas will interact a
little bit through pressure, but mostly, it's all gravity, and as the spiral galaxies
collide, they get mixed up. They lose their spiral
structure, and the end result is
something that looks a lot like an elliptical galaxy. Again, within galaxies,
the stars will form, and, particularly after the
first generation of stars, the primordial gas
of mostly hydrogen and helium has been
processed through starts and through supernova exploding
stars, return to the gases between the stars, and
the heavier elements have been formed. And those elements become dust. When a star forms in the
center of a rotating cloud, the material out in the outside of the clouds will
gather together and, through gravity, and
form the planets. The small, rocky planets
we think are formed closer to the stars, and the gas
giants are formed further out, along with the ices. After the planets first form,
sometimes there are planets that are in very similar
orbits near to each other, and we see evidence
for giant collisions in some solar systems. This is also the leading theory for the formation
of our own moon. The early Earth, shortly
after it formed, was impacted by another planet about the
size of Mars that kicked up a huge cloud of dust that
filled the whole solar system, and we see other solar systems that have these giant
dust clouds. The material was knocked away
from the earth, and reformed to be the moon, and
the Earth formed again from what was left over. So all of these are --
so that's another one of these we now know,
and some of the evidence for that actually came from
the Apollo moon landings and the rocks they brought back. Okay, so in comparison,
a comparison between the Hubble
space telescope and the James Webb space
telescope, it's successor, Hubble is a telescope that
kept at room temperature. We have sent astronauts up
there five times, and so, we maintain the telescope
at room temperature, so that the astronauts
can interact with it. The James Webb space
telescope is designed to detect infrared
light, and the problem with a telescope designed
to detect infrared light is that the telescope itself
will be glowing if it's at room temperature,
and that applies both to the Hubble space
telescope and also to the all the telescopes
on the ground. They are all glowing
in infrared light. So in order to make the James
Webb space telescope cold enough to detect infrared light,
we are going to cool it down to 225 degrees
below zero Celsius. That's minus 370 Fahrenheit,
or about 50 degrees above absolute zero temperature. And we do this by putting the
telescope behind a tennis court -sized five layers sun shield. This is one of the layers of
the sun shield being built up. Hubble is in what we
call low Earth orbit. It's 375 miles above the
surface of the earth. It goes around the earth
once every 90 minutes, but the James Webb space
telescope is going a million miles away. It will be launched
on an Ariane-5 rocket. This is a European-launched
vehicle and is provided as part of the European contribution to the James Webb
telescope mission. Webb is a joint project of
NASA, the European Space Agency, and the Canadian Space Agency. So Europe is providing
the launch, and it will be going
a million miles away to a special orbit called
the second Lagrange point. The second Lagrange
point, as the Earth goes around the sun once per year,
the second Lagrange point goes around the earth once per year,
keeping the sun and the Earth and the telescope all in a line. So that we can have both the sun
and the earth on the warm side of the sun shield, while the
telescope is on the cold side, cooling down to 225
degrees below zero. As I said, we want to have
a telescope that's bigger than Hubble, so that it
can collect more light, see more distant galaxies, and looked further
backwards in time. So Hubble's primary
mirror is 2.4 meters. That's just about like that big. Webb is 6.5 meters, which is
about the size of this room. Now as I said, Webb will be
launched on an Ariane-5 rocket, and the diameter of the Ariane-5
is 5 meters, which brings up the question, how do
you fit a 6.5-meter mere into a 5-meter rocket. Well, the answer
is a fold it up. So here's a picture, animation,
of what Webb will look like after it launches. It's launched all folded
up, and we will unfold it in about the first two
weeks after launch. So the first thing that
comes out is the solar panels to provide power and the
communication antenna, and then we'll start to unfold
this tennis-court-sized, five-layer plastic sun shield. The sun shield is launched
within these covers. We fold those back, and we start
to pull out the sun shield. The sun shield is made of
plastic material called Kapton, and each side of it
is actually different, but the side facing the sun
is very highly reflective to reflect the sunlight away. The five layers are each about
a foot, a little bit more than a foot apart, and of
course, this is in vacuum. So this works like a
giant vacuum flask, where the heat can escape between the layers
of the sun shield. Each layer is colder as
you get to the telescope. The last two deployments
are the secondary mirror on its support structure,
and then the two side wings of the primary mirror
are folded out. The mirror itself,
the primary mirror, is made up of 18
mirror segments. They're each made of beryllium,
which is a very light weight, stiff material, metal,
and you're coated in gold, which is highly reflective
of infrared light. You can see each of these
mirror segments is a hexagon, so that we can tile
them together, and it's 1.3 meters
across each segment. We installed 18 mirror segments onto this backplane
support structure, and I'll show you
how we did that. This was done at the
Goddard Space Flight Center, a little bit less
than two years ago. We used a robotic arm to place
each of the mirror segments onto the backplane, and then
the technicians attached it. While we were doing
this, for protection, we had these black protective
covers on the mirror segments. And... This process has been completed,
and then when it was all done, we took the protective
covers off, revealing the gold
mirror surfaces. Here's a picture of the
telescope itself, again. In the Goddard Clean Room,
we have a viewing window, and that need a good
opportunity for selfies. Here is the Senior
Project Scientist for Webb, Dr. John Mather, Nobel Laureate. He won the Nobel
Prize, essentially, for proving the Big Bang. I'm his deputy on this project. I wasn't actually there
when they did this, when they scanned the mirror
across, but I was able to have a picture of myself
taken with the mirror, and this is probably the
coolest selfie I will ever take, of myself reflected in a multibillion-dollar
gold-coated space telescope mirror. This is a very cool
picture, as well. This is done within the clean
room, the technicians who worked on the mirror, and reflected
in the mirror is the NASA logo from the back wall, and one
of the interesting things that you can see is that
this is not a flat mirror like you have in your bathroom. It is actually a lens
to focus the light. And so, they were able
to line up the NASA logo to fill the whole mirror. On back of the telescope,
we have four cameras. Each has a different capability,
including taking pictures in visible light
and infrared light. Webb is capable of detecting the
redder colors of visible light. It stops at gold color,
because the gold itself absorbs everything bluer than that. And it works out into
the mid-infrared. These cameras were
installed together into a structure
seen right here, and this shows the installation
of the camera package into the back of the
mirror, which is upside down. So the mirror is pointed
down in that structure. Again, this was done
in the clean room at the Goddard Space Flight
Center up in Greenbelt. And you can see, again, the viewing window had
lots of people in it. I actually arrived to watch
this just right at the very end. You can't see me in the video,
because the camera moves right at about the time
that I arrived. You can see that there's
a lot of people involved. There's both the people who are
doing the work and the people who are watching to make
sure everything is done, the quality assurance
and safety people. So right at about this
point is when I arrived, and I was able to
watch it go in. Okay, and the sun
shield is fully assembled and installed onto
the spacecraft. We now have the Webb
telescope is, or the observatory,
is now in two pieces. We have the spacecraft and
the sun shield fully done and current undergoing testing. We have the telescope and the
instrument package were tested at the Johnson Space
Flight Center last fall. They were there during
the hurricane. Both the equipment and
the people were okay. It was kind of exciting
time for them. So this is the vacuum chamber where we tested the
telescope and instruments. It was actually built
for the Apollo program and is human rated. So the astronauts
practiced walking on the moon in their spacesuits inside
this chamber back in the 60s. The Webb project took out the
simulated lunar surface and put in a inner what's called
a shroud that is cooled with liquid helium to get
down to the cold temperatures to test Webb, and here's
a picture of the telescope after that test, which
lasted three months when it was complete. Moving this large
telescope around, we have a special
shipping container. We actually, to go from Goddard
to the Johnson Space Center, we actually took the
telescope on the Beltway. It goes at a maximum speed of
about seven miles per hour, which made it very popular
with the people who were on the Beltway at that
time, but we do this in the middle of the night. So it went from Goddard
to Andrews Air Force Base, then flew on this
C5 cargo plane. We put the whole truck,
including the cab, inside the plane and
flew down to Houston. This shows how we drive it
around, going very slowly, to make sure that it doesn't
bump too much, and you can see, again, 4 a.m. Then taking it on the roads is an interesting
thing, because it's so big. You can see that we have
a crane here that pulled up the street lights to
get them out of the way as we drove it around. So the telescope now has been -- was completed the test
in Houston and was flown to the Northrop Grumman
facility in Los Angeles, where we're building the
spacecraft and sun shield. Oops. And so, now we have all
of the parts of the observatory in the same clean room. Here it is arriving
in Los Angeles. Again, the telescope with
the side wings folded up. The instrument package is in the
inside, and you can see the rest of the primary mirror here
on the bottom, and then, this is the sun shield in
its launch configuration. So it's all folded up with the
protective coating around it. The spacecraft, which
maintains position in its orbit, is down here, and this structure
is a simulation, or a mass model of this, and we're still going
to be doing some more testing of the space craft and
sun shield, and then, towards the end of
this calendar year, we'll put the two together,
do some final testing, and then we're ready for launch. Launch, as I said, is from South
America, Carew, French Guiana, and after this is
all put together, it becomes too big
to fly in that C5. So we're going to go by boat
through the Panama Canal. So, if you would
like to learn more about the James Webb space
telescope, we have a website, of course, JWST.NASA.gov. A constant stream of news. You can see down here the latest
news is this talk, but we also, whenever we make any progress,
we put it out on the website. We have Facebook
accounts, Twitter feeds, and other social media. So stop in and keep
tabs on how we're doing. Here's a picture of
a couple of our fans. You can see, on the set of the
Big Bang theory, we got a model of JWST back here and
some of our pictures. Webb was designed to study some
age-old questions that date back to the beginning of humanity. Where did it all come from? What are the origins? What are the changes over time? What is the process that went from the Big Bang 13.8 billion
years ago to the formation of galaxies, stars, planets,
and life and intelligence, where did it all come from? So I'd like to thank
you for your attention. I'm going to leave you with
one quote from somebody who inspired me when I was
the age of the children in high school, Carl Sagan. He said, "Somewhere something
incredible is waiting to be known." So thank you for your attention. I'd be happy to take questions. [ Applause ] >> Stephanie Marcus:
Thank you so much. We now know a little bit
more, and it's kind of fun to go behind the scenes to
see this all put together. So please ask your questions, and he will repeat them
so everyone can hear. >> Jonathan Gardner: Okay. >> So why is it being
launched in the South America? >> Jonathan Gardner: The question is why is it being
launched in South America? So the decision to use the
European launch was part of the early negotiations
for what -- in putting together
the partnership. It's not that the US
doesn't have launch vehicles, but that was what was worked
out that they would contribute. So where do you want to
put your launch site? It's good to be on a coast, so that you can launch
it over the ocean. It's good to be on the East
Coast, so that as you launch it over the ocean, you
get an additional boost from the spinning of the earth. You launch it over
the ocean just in case something goes wrong. You know, if pieces fall down. They go in the ocean. But you want to launch East,
heading east, so launch is on the East Coast, and
additionally, particularly if you're going into deep space,
you want to launch as close to the equator as you can. So the US primary launch
site is in Florida. Again, it's south, so
it's close to the equator. It's on the East Coast,
and the launches go out over the Atlantic Ocean. The European launch site
is in French Guiana. French Guiana is
a part of France. It is as much a part of France as Hawaii is a part
of the United States. So they have the infrastructure
of being part of France in a place that is
on the East Coast of the continent and
near the equator. Question? >> How many extra panel segments
to have to make as backup? >> Jonathan Gardner: How many
extra panel segments did we make as a backup? So there are 18 and
the telescope, and because a hexagon
has six-fold symmetry, that means there are
three different kinds of those -- in those
18 segments. Essentially, we call
it prescriptions. So three different
optical prescriptions, and those are then
repeated six times to make up the primary mirror. So we have three spares, one
of each optical prescription. >> What is the anticipated
life of the Webb telescope? >> Jonathan Gardner: What is
the life of the Webb telescope? So the lifetime is
limited by one thing that we use up, and
that is fuel. We need to use fuel to
maintain its position in -- it's actually in orbit
around the L2 point, not right at the L2 point. So to maintain that
position in orbit, we need to fire the rockets
about every two weeks or so. In addition, the sun
shield acts as a solar sail, and the telescope can build up
angular momentum, which we store in reaction wheels, and we also
need to use the fuel to get rid of that angular momentum. A telescope like Hubble
is in low-Earth orbit. It uses the Earth's
magnetic field to get rid of angular momentum, but with
Webb, we don't have that. So we need fuel. So we to have fuel. Fuel is the ultimate
limiter of the lifetime, and we have 10 years
of fuel on board. There's some margin in that. So we have a bit extra, and we
actually use a lot of our fuel, of our on-board fuel, to do
the final orbit insertion after launch. So if launch goes well,
we have extra fuel that we could use for lifetime. But there's a 10-year
requirement for lifetime. We also, the other thing that limits lifetime
can limit lifetime is if something goes
wrong, and we mitigate that by doing lifetime testing. So we will take an exact copy
of our mechanisms and run them through however long,
however many times we expect to use during the mission. And we're actually doing
lifetime testing for five years, because that's a very
expensive thing to do, to ensure that parts will last
and keep working for 10 years. We tend to only do that if we're
sending something out to Saturn, where it's going to take
10 years to get there. So lifetime testing
is five years, but that's always done it
a factor of two anyway. So we expect 10 years >> If it were to live beyond
its plan, is there a plan for [inaudible] fuel, if you found it's doing
really well after 10 years? >> Jonathan Gardner: So the
question is if it's doing well after 10 years and we're running
out of fuel, can we refuel it? There's always a plan. What there isn't is funding. So there are people that are
looking at this, in general, the servicing of space -- of
satellites, including refueling. Webb is not designed to be
serviced or refueled in the way that Hubble was designed
to be serviced, and we don't have the
capability to do that, but 10 years is a long time. Yeah? [ Inaudible Speech ] >> Jonathan Gardner: So the
question is what is the fuel? It's something called hydrazine, and I'm not a propulsion
engineer. So I'm not really
sure what that is, but it's certainly
not nuclear, no. It's not a very powerful rocket. The fuel that we have is,
I think, 300 kilograms, and that will last 10 years. So it's mostly just
doing small nudges, especially once it's all
deployed, we don't want to do very much acceleration. So it's very gentle. >> Is it solid? >> Jonathan Gardner: It's
not a solid fuel, no. No, it's either liquid or gas,
and I don't know which one. Probably liquid, yeah. Yes? >> Is the Hubble the
biggest and the best in the world, the telescope? >> Jonathan Gardner:
Is Hubble the biggest and best telescope in the world? Well, first of all,
it's not in the world. It's above the world. It's in space. So Hubble, it's not the
biggest telescope we have. The biggest telescope we have is
a ground-based telescope called the Keck telescope that's
10 meters in diameter, and therefore, even bigger
than Webb, but by being above the atmosphere, that
makes Hubble much more powerful than telescopes that
are on the ground. There's always a
bit of a trade-off. To build a telescope that's in
space, going to go to space, you have to make sure
that it can work remotely, in most cases, without ever
having the chance to fix it, and even with Hubble, it's very,
very expensive to go and fix it. Whereas telescopes on the
ground, you put it together, and you start it working,
and if something is wrong, you just fix it, and if you have
new technology for your cameras, you can just build a new camera
and put it on, and so forth. So essentially, what we do is
that we don't ever do anything in space that can be
done from the ground. If we can do something with
a ground-based telescope, then that's going to be cheaper than doing the same
thing in space. So space telescopes are
designed, all of them designed to do things that we cannot
do from the ground at all. So yes, in a sense,
Hubble is the -- by a lot of ways
of measuring it, Hubble is the most productive
telescope in history. It's the most powerful telescope
in history and has contributed to the most discoveries,
but that's partly because it's unique,
and likewise, Webb will also be unique. It will do things that we just
cannot do from the ground. There are also even bigger
telescopes being built on the ground, going up to 25
to 30-meter-diameter telescopes. Those will also be
incredibly powerful, particularly working
together with each of them using their
unique capabilities. >> What are the plans
for a space telescope or other telescopes
after the Webb telescope, beyond the Webb telescope? >> Jonathan Gardner:
So one of the plans for space telescopes after Webb? Well, so getting a little
bit into scientific politics for a minute, the
National Academy of Sciences holds what they call
a decadal survey every 10 years to recommend to NASA. They make recommendations
to NASA, the National Science Foundation,
for what to do in astronomy and astrophysics
over the next decade, and Webb was the number
one recommendation for NASA in astronomy in the year 2000, and that started the
project building Webb that's now culminating. In 2010, there was
another decadal survey, and the academy panel
recommended a project called the wide-field infrared space
telescope, or W First. This is a telescope that is the
size of Hubble but has a much, much larger field of view, a
factor of 100 times bigger part of the sky, and it will do big
surveys across the sky, aiming, in particular, at three
scientific questions. One is what is the dark energy? How can we characterize the
effects of the dark energy on the history of the universe? So in comparison to
the original discovery of dark energy was made with
study of about 40 supernovae, these particular
type of supernova. Further study with W First
will have hundreds to thousands of those type of supernovae,
get a much better measurement and learn more about the
properties of the dark energy. That telescope also will
be looking at exoplanets, both through a statistical
study, looking at all of the exoplanets in a region,
looking towards the center of our galaxy, and then, also, using a technique
called choronography, where it puts the spot in
front of the star and tries to detect the light
from the planet itself. And then, finally, because
it's a big survey telescope, it's going to discover
lots of new types of things that can be used for lots of
other astronomy questions. So that was a recommendation
from the 2010 decadal survey, and we're in the design
phase of that telescope. And then, what comes
after that will be up to what we call the
2020 decadal survey, which is just being formed. The national Academy
is just starting to choose the members
of that committee. These decade-old surveys
are a big process. They asked for submissions
of white papers from astronomers
across the country. They usually get about 200
suggestions of what to build. In the running for the next
big space telescope include a telescope that would be
even bigger than Webb and would be optimized to
study extrasolar planets, in particular, looking at
rocky planets and trying to find what we call biomarkers. So things like, for example, in
the earth's atmosphere, oh zone and methane are in
dispute equilibrium because of the presence
of life on earth. We're affecting life in general,
going from bacteria to people, affects the atmosphere of
the earth in a way that, if there were no life
would not be sustainable. So looking for that
kinds of things is one of the big questions that we
need an even bigger telescope than Webb and something
that's optimized to do that. So that's one possibility. Other possibilities in the running include
a big x-ray telescope to study black holes and a
gravitational wave observatory. And anyway, there's a number
of different possibilities for what comes after W First. So we have Webb, then W First,
and then the next big thing. Yeah? >> Hubble was afflicted with
some initial aberrations that were fixed by astronauts,
I think, in the spacewalk. Can you characterize that
force and what you do to make sure there's
nothing wrong with it? >> Jonathan Gardner: Right, so the question is Hubble was
launched with some aberrations on its mirror that were
fixed by the astronauts, and what are we doing with Webb? So first of all, the
problem with Hubble was that the mirror was ground,
it was shaped precisely to the wrong prescription. There was a problem with the
test equipment that was -- making a highly precise
mirror is somewhat of an iterative process. You polish it into a shape. You measure the shape. You polish again and go back
and forth, and with Hubble, there was a problem
with the test equipment, and so they ground it
perfectly to the wrong shape, which meant that when the
astronauts could go up there, they can install
a corrector lens that exactly fixed the problem,
because it wasn't a, you know, an error or a roughness problem. It was just the wrong shape. So one of the things
that was done with Hubble to save money during
its construction was that they did not do a full
end-to-end optical test where they shine light
on the primary mirror, all the way through
to the instruments to measure that light. That's a very expensive test. With Webb, since we
don't have a plan for servicing, we did that test. That's what we did in Houston. Took three months, almost,
yeah, just a 100-day-long test. We did shine light onto
the primary mirror. It bounced into the
secondary, into the instruments, and measured that
everything was okay. During that test, the vacuum
chamber took seven tanker trucks of liquid nitrogen per day. That just kind of shows
the scale of that test. There were about
50 people working. Fifty people on each shift,
and it went round-the-clock. During the hurricane, we almost
ran out of liquid nitrogen, and so, the president of
the company was called, and he ordered that
extra trucks would come in during the hurricane. So this was kind of an all
hands on deck type of thing, and that testing is what will
ensure that Webb will work. Know the specific problem with
the mirror that Hubble had, Hubble has a solid-glass mirror. Whereas Webb has the
18-mirror segments. Each mirror segment is
adjustable on orbit, and we plan to adjust
them about every 2 to 3 weeks during the
lifetime of the mission. We'll tweak up the positions
of those 18 mirror segments. Each one of them can be
moved six different ways. So that's back and forth, up
and down, tipping, tilting, and rotation that six
different degrees of freedom. We also have a thing
that can poke the back and change the radius
of curvature of each of the mirror segments. All of that together means
we can take out a lot of the exact type of problems
that the Hubble mirror had. So, but basically, Hubble
is actually an exception. It was the only major NASA
space telescope, or mission, that was designed to be serviced
in the way by the astronauts, and it was designed
from the very beginning with servicing as
part of the plan. Webb, because it's going
a million miles away, because it's a big,
very sloppy structure, and because it's cryogenic. It's these ultra-cold
temperatures, all that led to the decision that we would
not plan to do the servicing. That's something that kind
of goes back and forth on the question of do
we plan for servicing, and some of the future
missions they're looking at servicing again,
as a possibility. Yeah? >> It seems like a huge risk
that it's not serviceable, and it's obviously very complex. So if there's -- it seems like if there's the
slightest problem here, you put all your
eggs in one basket. >> Jonathan Gardner:
Yeah, so the question is that seems like a big risk. If there's a problem, then we
don't have a way of fixing it. So in addition to a
complex testing program where we test everything, we test everything
at multiple levels. So we'll get a detector,
and we test it. We put it into the camera. We test the camera. We put the camera
into the structure. We test that. We put that together
with the telescope. We test that. There's this hierarchical way in which we are testing
everything multiple times as we put it together. So in addition to that,
we also have backups for every credible
single-point failure. So for example, electronics. We have dual electronics, and we can switch back
and forth between. So if an electrical component
goes bad, we can bypass that and bring the signal
around on the other side. All the motors, all the
mechanisms, have dual windings. So we can -- we have a
backup for that, as well. The deployments themselves can
be done in both directions. So we do it. If it doesn't latch, we can
try again, and so forth. Essentially, yes, you're right. It's risky business, but this
is what NASA normally does. Hubble is the only big project that was designed to
be fixed in orbit. Yeah? >> How soon after launch will it
be positioned and will it start to actually provide data? >> Jonathan Gardner: So
the question is how soon after launch will it be in
position and doing science? So it will finally be ready
six months after launch. That six months, it takes about
a month to get into position and to do all the deployments. It then, once the sun shield
is out, it starts to cool. When it's cold enough that
we can turn on the cameras, which don't work at
room temperature, we will point the
telescope at a bright star, and we'll see 18 different
out-of-focus images of that star. So then we have to move
the 18 mirror segments so that they all line up to a
perfect uniform optical surface. That's a process that we call
commissioning the telescope. That will take another
three months or so. And then we have two months for
turning on all of the cameras and checking out all of
the different filters and modes and so forth. So the plan is to start routine
science observation six months after launch. >> Stephanie Marcus:
I guess we better end. Thank you so much. >> Jonathan Gardner:
Thank you for coming. [ Applause ] >> This has been a presentation
of Library of Congress. Visit us at LOC.gov.
