NOVA

MISSION CONTROL

Lift off of the Space Shuttle Discovery with the Hubble Space Telescope. CAPCOM, we have a go for release.

NARRATOR

It may be the boldest experiment ever undertaken in astronomy... (cheering)...with a legacy that will endure for centuries.

WOMAN

You have been awarded the Nobel Prize in Physics.

MATT MOUNTAIN

The Hubble Space Telescope is probably the most scientifically productive instrument in history.

NARRATOR

This single tool-- the Hubble Space Telescope-- has revealed the size and age of the universe, the birthplace of stars, and the existence of black holes. It's helped us find planets like our own in far-off solar systems and a mysterious force-- dark energy-- that makes up about 70% of the universe.

AMBER STRAUGHN

The Hubble Space Telescope has completely changed the way that we as scientists understand the universe.

NARRATOR

The story of Hubble is a story of discovery. It's also the story of one of the biggest blunders in the history of science.

SANDRA FABER

This is the moment we find out that we are doomed to failure. Is it possible that you could bring the telescope back?

NARRATOR

And of the genius and courage that saved the day.

STORY MUSGRAVE

The moment of truth is coming. You can't run from it anymore, it's coming, there it is.

NARRATOR

Now, on Hubble's 25th anniversary, NOVA tells the remarkable tale of how this magnificent machine was built, how it has solved some of our most enduring mysteries, and how it is showing us a universe as beautiful as it is astonishing. "Invisible Universe Revealed"-- right now on NOVA.

Major funding for NOVA is provided by the following

At Cancer Treatment Centers of America, NOVA and promoting public understanding of science. And the Corporation for Public Broadcasting.

NARRATOR

Since the dawn of humanity, we've looked to the heavens and wondered, how old is the universe? How many stars are there in the sky? Are there other planets out there like our own? But in the last 25 years, there's been a revolution...

all because of a machine called Hubble. Traveling in space, high above the distortions of our atmosphere, gives this giant telescope great power.

MATT MOUNTAIN

It's the size of a school bus. It's traveling at 17,000 miles an hour. It's 300-and-something miles above your head. But in there is one of the most precise mirrors mankind has ever built.

NARRATOR

Billions of times more sensitive than our own eyes, the space telescope has literally brought the universe to us, making more than a million observations. One legendary image is called the "Pillars of Creation." It's a giant plume of gas and dust where stars are born. Our own sun probably formed in a place like this.

AMBER STRAUGHN

The whole region is something like 400 trillion miles, so it's massive, it's huge. But still within the context of our own Milky Way, it's just one little part.

NARRATOR

Hubble has also captured pictures of places where stars die. These are planetary nebulae-- remnants of expiring stars. They look like artworks in the heavens. Each one of them is different, like snowflakes.

And these are some of the most spectacular images that Hubble has produced. Hubble has shown us that black holes are real. A giant one sits at the center of our galaxy and nearly every other we know. It's discovered the age of the universe and that there are more stars in the heavens than grains of sand on all the beaches and deserts of the world combined.

Over the past 25 years, Hubble has told us a story of creation, destruction, and of vast, new mysteries that beckon our curiosity. But putting it in space long seemed an impossible dream, even to those who took on the challenge.

NANCY ROMAN

I started out in optical astronomy and spectroscopy. But as a woman in my generation, I could not get tenure at a research institution. In 1959, when NASA was formed, one of the men there asked me if I knew anyone who would like to set up a program in space astronomy. And I decided that the idea of influencing astronomy for 50 years was just more than I could resist, so I took the job.

NARRATOR

Astronomer Nancy Roman is known as the mother of the Hubble. She worked on its design and development for nearly 25 years.

ROMAN

If I brought anything to it, it was perseverance and belief that it was possible.

NARRATOR

The idea of a space telescope was first seriously proposed in 1946 by Princeton scientist Lyman Spitzer. He was the scientific visionary, and Roman was the force that pushed this vision forward, decades before the technology was up to the task. Even into the mid-'60s, just getting a rocket safely into space was a challenge.

ROMAN

There were a lot of failures. We were babies learning how to walk. And we didn't always succeed. Babies fall down, and we did too.

NARRATOR

But however far-fetched at the time, the lure of getting a telescope above the distortion of the earth's atmosphere was strong. The major challenge facing astronomers was the twinkle of the stars.

LIVIO

Twinkling stars are an inspiring source of poetry, but in terms of observing stars, it's not very good.

JIM CROCKER

If you can imagine you're swimming on the bottom of the swimming pool and you look up and you see the distortion. It's like a fun house mirror. That's what it's like to study stars from the surface of the Earth. The atmosphere is just like that water in that pool.

It sloshes around and moves and distorts the image. But when you come up out of the water, everything's clear. That's exactly what happens when a telescope gets above the atmosphere. In the pristine vacuum of space, light can travel for billions of light years, undisturbed.

NARRATOR

The atmosphere not only distorts light, it prevents some from reaching the ground at all.

ROMAN

So for those reasons, astronomers for a long time were eager to get something outside. And so I got a committee together, and that was the beginning of the Hubble.

NARRATOR

The space telescope was named for Edwin Hubble, the great astronomer who did much of his pioneering work in the 1920s at Mt. Wilson Observatory in California. In those days, our own galaxy, the Milky Way, was considered the entirety of the universe. Nearly everyone, even Einstein, believed the universe had existed forever in its present state-- that it was eternal and unchanging.

But Hubble would prove them all wrong. He began by figuring out how far away the stars he was seeing actually were.

LIVIO

At the time of Edwin Hubble, it was hard to measure distances. It still is even today.

NARRATOR

It's difficult to know if a star appears bright because it is actually bright or simply because it is close to us. So Hubble searched for a rare type of star called a Cepheid variable. Cepheids pulse at a known brightness, so by measuring the amount of light he could see, he could calculate how far away the star actually was. In October 1923, Hubble found a Cepheid in a gaseous cluster of stars then called the Andromeda nebula.

It yielded a shocking discovery.

MOUNTAIN

When he actually did the calculations, he discovered Andromeda was roughly a million light years away from us, which is outside our galaxy.

NARRATOR

Andromeda was its own galaxy.

MOUNTAIN

Oh, there are other galaxies out there, and we're just one of them.

NARRATOR

For the first time in history, there was evidence that our universe stretched far beyond the Milky Way.

MOUNTAIN

But then what he did was he measured the speed of a whole bunch of these galaxies.

NARRATOR

Edwin Hubble measured speed by looking at the light the galaxies emitted. He knew if the galaxy was moving toward him, the waves would shorten and shift to the blue part of the spectrum. If it was moving away, the waves would lengthen and shift to the red.

LIVIO

Every distant galaxy Hubble looked at, he saw the light from it being red-shifted, which meant everything is moving away from everything else.

MOUNTAIN

And he found the further away they were, the faster they were going.

NARRATOR

In fact, the universe itself was expanding, stretching the light from the galaxies. Edwin Hubble had changed our understanding of the cosmos forever.

MOUNTAIN

The whole universe was clearly expanding. And so this was the discovery of the expansion of the universe. You know, which Einstein said, "Well, that's crazy, right?" The discovery of the expansion of the universe of course was a very strong piece of evidence for a beginning. If everything is now expanding, you can run this backwards and see that everything should have started from a certain point or singularity, what we today call a Big Bang.

That was pretty radical and mind-blowing stuff back in the '20s and '30s, and some people today even find it mind-blowing.

NARRATOR

Hubble's discovery opened up the modern era of astronomy and raised huge questions, like "How old is the universe?" But astronomers couldn't see clearly and deeply enough into the cosmos, so the mystery would endure for decades.

LIVIO

Determining the age of the universe was definitely one of the key goals of the launch of the Hubble Space Telescope. Astronomers used to have fistfights whether the universe was ten billion years or 20 billion years old until we launched the Hubble Telescope.

NARRATOR

But first, they would have to build it.

ROMAN

I realized that my job at NASA to a large extent was salesmanship. And it was a particular problem with Congress. We can cut the space program sharply. Congress has already cut that $400 million and I think we can cut it a billion dollars, and we should cut it a billion dollars.

Proxmire was quite famous as a senator of picking out projects that he thought were stupid. We have a war going on in Vietnam. And he asked NASA why the American taxpayer should pay for something like the Hubble. And I came up with the answer that for the cost of a night at the movies, every American would have 15 years of exciting discovery.

NARRATOR

Finally, after more than a decade, the plans were approved in 1977. Hubble's power would come from an eight-foot wide mirror. It would gather light from across the universe. To magnify the sky and see tiny details, it would need a long distance to focus the light and give a clear image.

But a space telescope needs to be compact, so Hubble would use a second mirror to further magnify the light and focus it onto the cameras. For it to work, the mirrors would have to be perfect. Hubble was the most precise optical mirror ever made. No place along its surface could have deviated from a perfect curve by more than a millionth of an inch.

An optics company, Perkin-Elmer, was chosen to do the work, in part because it had already made mirrors for spy satellites.

FABER

They told NASA, "We know how to do this, and this technology is proprietary. "We are not going to let you come in and watch what we are doing." So NASA got a rather limited view of what was going on in that little group.

CROCKER

They had very, very precise instruments that they designed just for polishing this mirror. They had to work at night so that the vibration of cars in the parking lot wouldn't cause problems with the polishing equipment. They had to isolate it and float it on a table so any vibrations from the building wouldn't come in. And this program was over budget, behind schedule.

They were desperate to get the telescope built and flown.

NARRATOR

Perkin-Elmer's own measurements showed discrepancies in the surface of the mirror, but this was never passed on to NASA. The telescope was declared ready for launch, a disaster waiting to happen. (applause)

ED WEILER

The hopes and dreams of the world's astronomers were with us that day at Cape Canaveral. The last time astronomers leapt a factor of ten in observing capability was when Galileo, in 1610, instead of using his eye, put the telescope in front of his eye.

ANNOUNCER

And liftoff of the Space Shuttle Discovery with the Hubble Space Telescope, our window on the universe!

WEILER

All increases in capability after Galileo were incremental. They weren't leaps of a factor of ten, until Hubble.

ASTRONAUT

Mission Control, Houston.

MISSION CONTROL

Roger all, Discovery.

WEILER

We thought, "Let's go, we're off to the races!" Little did we know the time bomb that was ticking. Little did we know.

MISSION CONTROL

Discovery, Houston. You have a go to open the doors.

NARRATOR

After nearly 30 years of planning, on April 25, 1990, astronauts used a robotic arm to deploy the Hubble space telescope in orbit 380 miles above the earth.

ASTRONAUT

CAPCOM, we have a go for release.

MISSION CONTROL

We concur, Charlie.

ANNOUNCER

Mission control, Houston confirms, the Hubble Space Telescope is released. (cheering)

NARRATOR

With the telescope finally in place, everyone was excited to see what it could do.

REPORTER

...make final adjustments before we get to see the clearest pictures ever seen in the history of astronomy.

MISSION CONTROL

Nose gear touch down.

NARRATOR

But when the first images arrived, they weren't quite what the scientists had expected.

MOUNTAIN

When they first saw these images, they just assumed the telescope wasn't in focus. They tried to move the focus backwards and forwards, but the light kept being blurred like it was always out of focus. It was really quite a shock.

FABER

We were very worried.

LIVIO

I just couldn't believe it. It definitely was a huge shock. We were supposed to revolutionize astronomy. How is it that we can't focus this telescope?

How is this even possible?

NARRATOR

After weeks of investigation, horrified astronomers suspected something was wrong with the mirror. This is my logbook that I kept during the early days of Hubble. Daily, we went to meetings, and we kept a record of everything that was happening. Here is a particularly interesting day.

We were told about the actuators on the back of the mirror. The actuators might be able to fix small errors in the surface of the mirror by pushing and pulling on it, So this says, "One half wave is 7 times the dynamic range," meaning the problem is seven times worse than they could fix.

And here's a little note I wrote

"This is the moment we find out that we are doomed to failure!"

NARRATOR

Sandra Faber and her colleagues realized that the problem was massive and lay at the very heart of the telescope.

FABER

The Hubble telescope has a big primary mirror that collects the light, and then there's a secondary mirror which reflects the light back down to the detector. So if everything is working, every zone of the primary mirror should come to a focus at exactly the same location.

NARRATOR

With a single focal point, a star would appear crisp and bright. But this wasn't what was happening.

FABER

As I looked at those star images, I could see that the problem with Hubble was the rays are coming to a focus at different points. And that is the classic problem called spherical aberration. This is the actual set of images that my team presented that convinced people of the spherical aberration. The top set of images is simulated with software, the bottom is the actual images, and the fact that they match is what shows that we really understood what was going on.

WEILER

That was the kiss of death. It was like a bullet to the head. So I said, "Well, what are we going to do?"

FABER

Should we declare this telescope to be junk and just end it? Can we use it in its present form and get something out of it? Can we fix it? And all of those thoughts were running through people's minds in those fateful days after this discovery.

NARRATOR

Somehow, the mirror had been polished too flat, and there might not be anything anyone could do to fix it.

WEILER

It was probably early June when people starting saying the "S" word-- spherical aberration. That lead up to the infamous press conference that I'll never forget as long as I live. What might have made this happen? Do you know for sure that that the aberration is in the primary mirror, the secondary mirror, both?

Why wasn't it caught on the ground?

MOUNTAIN

This was one of the most expensive science projects that NASA had ever undertaken, and it was a techno-turkey. Is it possible that you could bring the telescope back? It was an absolute disaster. And so it became life and death for NASA itself.

It was the national joke.

CROCKER

We went from being the heroes of the universe to the Mr. Magoos, and being associated with the telescope was difficult.

NARRATOR

A NASA board of inquiry searched for clues to what went wrong. Inspecting every piece of every tool used to polish the mirror,

they found the smoking gun

a few missing chips of paint. They had thrown off the laser-guided measuring tool used to shape the mirror.

CROCKER

Everything was off about a millimeter. And so they polished the edges of the mirror a little too flat, about 1/50th of the thickness of a human hair.

NARRATOR

Many feared this meant Hubble was dead, since the mirror was hard to access and impossible to remove in space. Sandra Faber was on the panel tasked with finding a solution.

FABER

A blue ribbon committee convened. People were thinking about everything from bringing the telescope down to having astronauts go up in orbit and swim down into the tube and install correcting optics in front of the primary mirror. I called the report, jokingly, "50 bad ways to fix a space telescope."

NARRATOR

The best idea was to put small corrective mirrors in front of the cameras and other instruments. But the problem was getting the mirrors inside the telescope. Jim Crocker was an engineer in charge of Hubble operations.

CROCKER

We got to the point where it's like, "We're kind of running out of ideas here "and not sure what to do. "There's a lot of ways to fix this, there's just no way to perform them in space." (shower running) I actually came back from the meeting and went back to the hotel that we were staying at and I thought, "Well, I'll take a shower before we go out to dinner." The showerhead is on a sliding rod, and the head goes up and down. And so I turned the water on and I slid it up, and then it was like it clicked. If we packaged the mirrors into a little robotic arm and we put that arm into a new instrument, you could raise this mirror up and flip the little mirrors out in front of each of the other instruments and correct them all.

And I thought, "Huh, that'll work."

NARRATOR

NASA agreed and immediately started work. Astronauts would install an instrument called Costar. Once in place, its four arms would flip out, like the showerhead, and essentially give Hubble glasses. But no one had ever done anything remotely this intricate in space.

STORY MUSGRAVE

When I got the job, I didn't smile and I didn't celebrate anything. I says, "Here we go. I'll do the best I can with this." I told NASA and I told the media, they're all saying we're going to fix it, and I told them, "I don't know if we're going to fix it."

NARRATOR

Musgrave and a team of astronauts trained for 20 months preparing to fix Hubble.

MUSGRAVE

We choreograph this dance down to every finger and every toe. You know, a great ballerina, it's every finger and every toe. You can't have something messed up. You can't exactly mimic what you're going to do there.

So in your imagination, you watch yourself work. Then it is practice, so that you can pull it off when you have to.

NARRATOR

To simulate working in space, the astronauts spent 400 hours underwater rehearsing on a mock-up of Hubble.

MOUNTAIN

I think the most incredible thing about this is that the astronauts were prepared to risk their lives to go and fix a scientific instrument. (radio chatter) We know the shuttle was not a perfect machine. After all, there's been two disasters.

MUSGRAVE

I had a one-in-ten chance of dying. I don't like those odds. But it's not a matter of fear. You've decided ahead of time it's what you do in life.

MISSION CONTROL

And we have lift-off. Lift-off of the Space Shuttle Endeavour on an ambitious mission to service the Hubble Space Telescope.

MOUNTAIN

In eight minutes, they went from zero to 17,500 miles an hour.

MUSGRAVE

It's rough, and the vibrations are very rough. It's a butterfly bolted onto a bullet, you know, that's what's going on.

NARRATOR

It takes the crew two days to catch up to the telescope.

MUSGRAVE

As soon as I caught that bright star out there, it had to be Hubble, nothing else. The moment of truth is coming. You can't run from it anymore, it's coming. There it is.

MISSION CONTROL

En deavor, keep monitors disabled, and you've got a go for capture.

NARRATOR

The crew will do five spacewalks-- at the time, the most ever attempted on a single mission.

ASTRONAUT

Okay, visors as required.

NARRATOR

On the third walk, Musgrave and astronaut Jeffrey Hoffman need to replace Hubble's wide field camera. It was designed to capture a broad range of light frequencies across a large area of the sky.

ASTRONAUT

Oh, look at that baby, beautiful spanking new!

NARRATOR

The most critical moment comes when Musgrave takes off the camera cover. As he removes it, he exposes the camera's delicate mirror.

ASTRONAUT

Gonna touch the release. I want it down lower.

MUSGRAVE

Coming off, if you touch that mirror, it's over. If you touch that thing, every image that comes down from Hubble has got your little fingerprint on it. And that's very bad form.

ASTRONAUT

I want it down lower.

NARRATOR

Scheduled to take more than four hours, the crew pulls off the meticulous repair in half the time.

MISSION CONTROL

You got about two feet to go. You're looking real good.

NARRATOR

Finally, the team turns its attention to Costar. Astronaut Kathryn Thornton pulls out an old instrument to make room for the new corrective mirrors, packed inside a huge case.

MOUNTAIN

You saw these massive, great, refrigerator-size instruments that had to be maneuvered precisely into place. It became a real drama. Would they do it? Would they get it in?

NARRATOR

After two hours, the instrument fits exactly as planned.

MUSGRAVE

We did our job. We were pretty happy with the job that we did. But even if, yes, we did the job perfect, I didn't know what the result would be. Sit down, Chris!

(laughter)

NARRATOR

Back on the ground, the room is packed as they prepare to receive the first images.

LIVIO

I told somebody at the time that it was almost like when your child is born, you know, you sort of think that everything is going to go right, but you really don't know.

WEILER

I'll never forget it. I mean, I'll remember the birth of my two kids and the night we saw the first image from Hubble. We were all huddled around the screen, and I will never forget when that screen lit up and first appeared a little dot right in the center. (cheering) We did it!

And that by itself was good news because there was no fuzz around it. But then more and more little dots, stars, start showing up, until the whole screen was filled with crystal clear points of light. And all the faint stuff we were never seeing suddenly showed up. And we knew we had fixed Hubble.

(cheering)

LIVIO

Once we saw the new images, we knew that that's it, they nailed it.

FABER

Astronomers leaped to their feet and applauded and cheered and whistled and hooted-- it was unforgettable. It was a stunning success in the end. You know, the trouble with Hubble was over.

NARRATOR

With the space telescope now fully living up to its design, scientists could finally begin to solve some of the timeless mysteries of the universe. The solutions to many of these mysteries lie in the countless beautiful images Hubble has sent back, the most detailed ever taken of the heavens.

LIVIO

You cannot help but be in awe when you look at Hubble images.

STRAUGHN

In addition to these images being beautiful, they help us to answer the questions that humans have been asking forever.

NARRATOR

Questions like where do stars and planets come from? And this Hubble picture of the Orion nebula gave us unprecedented insights.

STRAUGHN

This particular image is so incredibly detailed, we can see stars forming. All of this background colorful structure is hydrogen gas. When gravity starts to take hold, the hydrogen atoms come together and undergo a nuclear reaction, so they start to form a star. And so a lot of what you actually see in this image, all of these bright dots are these things.

They're newborn stars.

NARRATOR

This single image reveals 3,000 newborn stars. And it also showed astronomers something else they'd never seen before.

STRAUGHN

If you zoom in and look really close, what you can see are these very cool, little proto-planetary discs. So these are tiny little solar systems that are starting to form. Our own solar system was probably in a very similar state billions of years ago, so the sun and the Earth and all the planets were contained inside this disk of dust. What Hubble did was it really opened the door for us to image these disks and be able to see them with our eyes.

NARRATOR

Hubble can see light up to four billion times fainter than the human eye.

MOUNTAIN

It can point to the most distant galaxies in the universe and stare at them continuously without moving while it's flying around the Earth at 17,000 miles an hour.

This has allowed astronomers to solve another enduring mystery

how many stars are there in the universe? They did it by zooming in to a tiny patch of sky.

MOUNTAIN

We wanted to find out, what happens if we just stare at a blank piece of sky? About the area you would see if you looked at the sky through a drinking straw. And so we stared at a single point in the sky, a blank point, for about ten days.

NARRATOR

In this seemingly empty sliver of sky, Hubble revealed 10,000 points of light.

MOUNTAIN

Every point is another galaxy.

LIVIO

Each one of those galaxies is a collection of about 100 billion stars like the sun.

NARRATOR

Every galaxy is made of stars, dust, and planets in solar systems like our own.

MOUNTAIN

As you fly through the whole almost 12 billion years of cosmic history, you start to see galaxies change as you go deeper and deeper in. And right at the very end, you see these really sort of orange and red fuzzy little blobs, which are the very earliest galaxies.

LIVIO

In visible light, these are the deepest images of the universe.

MOUNTAIN

So in a point in the sky no bigger than a drinking straw, there are 10,000 galaxies. So it told us instantly there were 200 billion galaxies in the observable universe. Each galaxy has roughly 100 billion stars. You do the math, and it tells us how many stars there are in our observable universe.

It's two with 22 zeroes after it. We didn't know that before the Hubble Space Telescope went up.

NARRATOR

The telescope would also help answer

another one of the most profound mysteries ever contemplated

how old is the universe?

MOUNTAIN

The Hubble Space Telescope represents exploring in a true sense. You don't know what you're going to find.

NARRATOR

The discovery of the age of the universe would take a circuitous route, building on Edwin Hubble's breakthrough that showed the universe is expanding. It would also set the stage for a shocking surprise.

SAUL PERLMUTTER

Everybody had known for many years that the universe was expanding, but everybody had assumed that the universe would slow down in that expansion because gravity would attract everything to everything else, and that would slow the expansion. And the big question was, is there enough stuff in the universe to gravitationally attract the universe to come to a halt?

ADAM RIESS

Is gravity retarding it enough that eventually, the expansion will stop and then the universe would start contracting? And so we wanted to measure as far out as we could, as far back in time as we could, the past expansion rate of the universe and compare that to today.

NARRATOR

Like Edwin Hubble had decades before, the scientists needed to find stars of known brightness so they could accurately measure distances. Hubble had used Cepheid variables, but Perlmutter and Riess searched for something called a Supernova Type 1a. These exploding stars all burn with the same peak brightness, five billion times brighter than our sun. But the trick was to find them.

PERLMUTTER

They really are rare. They only explode a couple times per millennium in a given galaxy of a hundred billion stars. And for that matter they don't give you any advanced warning. You don't know when it's going to happen.

And then once a supernova explodes, it brightens in a few weeks and it's faded away in a few months. But if you can observe some, oh, 50,000 galaxies in the course of a night, and then if you can wait a few weeks and come back and observe the same 50,000 galaxies, now you have reasonably good odds that new supernova will have exploded in some of those galaxies.

NARRATOR

The Hubble images made it possible to measure how far away the supernovae were and how long it took their light to reach the earth, even when they had exploded billions of years in the past.

PERLMUTTER

And that's, of course, the whole game here, because you need to be able to tell the brightness of that supernova to tell exactly what point in time in history you're looking at.

NARRATOR

With the same technique Edwin Hubble had used-- red shift-- Perlmutter measured a distant supernova's light to see how fast it seemed to be moving away. He expected to see that the expansion of the universe was slowing down, but he was in for a surprise.

PERLMUTTER

It was seven, eight billion years back in the past, and that one supernova suggested that the universe was not slowing down. And this was very interesting, very puzzling.

NARRATOR

His team then analyzed 42 more supernovae and came to a shocking conclusion.

PERLMUTTER

That data set strongly suggested that the universe was actually speeding up.

NARRATOR

Adam Riess was part of a competing group, and his work was yielding the same odd result. Looking into the past, he expected to see that the expansion of the universe had slowed, but five billion years ago, it started to accelerate.

RIESS

You know, you worry a tremendous amount because there are many ways to get a measurement like that wrong, pretty much only one way to get it right.

PERLMUTTER

The two teams working on this at this point were in really a type of rivalry. We were not talking to each other about what we were finding at all.

You wake up at 2

00 in the morning and you think, "Oh, my God, did I account for some subtlety?" We knew that if we got anything wrong, the other group would be sure to point it out. Did I subtract it from the total? Is this right? And you know, it's like cosmic accounting, and you gotta make sure that it's right.

NARRATOR

But the numbers were correct. Within weeks of each other in 1998,

the two teams announced the same shocking conclusion

the expansion of the universe was speeding up.

ANNOUNCER

You have been awarded the Nobel Prize in Physics for the discovery of the accelerating expansion of the universe.

NARRATOR

Perlmutter and Riess, together with Riess' team leader Brian Schmidt, shared the 2011 Nobel Prize in physics. (applause) But their discovery had opened up a whole new mystery. What was fueling the acceleration? Scientists called it dark energy.

PERLMUTTER

Something like 70% of all the stuff in the universe has to be made of this dark energy for the universe to be accelerating the way it is. And so it's possibly the most important stuff in the universe, and we don't know anything about it. I don't really know what dark energy is. We don't have an explanation that would satisfy really anybody, especially a physicist.

And so it's blowing everybody's minds again. Physicists call this the most important problem in physics because we don't know where this dark energy's come from. We can't calculate where it's come from. Our models don't work.

NARRATOR

But despite the mystery, the discovery helped finally resolve the question

astronomers had dreamed of answering for centuries

how old is the universe?

PERLMUTTER

You need to know that history of when was it faster, when was it slower if you're going to piece it all together and work our way back to the point at which all the distances would go to zero, the beginning of the universe. The Big Bang.

NARRATOR

Scientists found Cepheids and supernovae stretching far across the universe. They used Hubble to measure their distances and red shift to figure out how fast these points seemed to be traveling away. This revealed how long the total expansion had taken since the Big Bang.

FABER

Hubble provided a ruler for the universe. So when you put together the basic size and the history of how fast things were going in the past, you get 13.7 billion years.

NARRATOR

Our universe is 13.7 billion years old. Hubble had finally helped answer this fundamental question.

LIVIO

There was a promise, and Hubble delivered on that promise.

NARRATOR

And then, nearly a century after Edwin Hubble first glimpsed galaxies beyond our own, the space telescope took on another profound question. How do galaxies actually form? At the center of the mystery, black holes-- regions so dense that nothing can escape their pull.

FABER

The basic idea of a black hole is the gravity's so strong that nothing can escape. Even light cannot get out. We can't take a picture of a black hole directly. It's black.

So how do we know it's there? We know it's there by studying the way stuff moves in its vicinity. Things orbiting close to it are gonna go very fast, but you have to get very close to the hole in order to see that effect.

NARRATOR

Scientists had theorized but never proven the existence of supermassive black holes billions of times the mass of our sun until they used Hubble to look at the core of a galaxy called M87.

FABER

It was the superior spatial resolution of Hubble that was the key. In the galaxy M87, the gas on this side is coming towards you and the gas on that side is going away from you. And we can measure the motions

and calculate the mass of the black hole

three billion times the mass of our sun.

NARRATOR

But how common are these giant black holes? Sandra Faber's team used Hubble to measure the speeds of stars orbiting around the center of other galaxies and discovered something remarkable.

FABER

We accumulated measurements of stellar speeds in I would say two dozen galaxies, and in every one we found evidence for a compact central mass. Essentially, at the center of almost every galaxy, there is a supermassive black hole. There is some regulating mechanism here that makes the black hole and the bulge of stars around it grow together. So it is a chicken and egg problem in the sense that did the galaxy form first and then a black hole grew inside it, or did the black hole kind of seed the formation of the galaxy?

And we're actually not sure what the answer to that is.

NARRATOR

The precise relationship between supermassive black holes and galaxies remains a mystery. It's just one of the countless questions and profound discoveries generated by Hubble over its 25 year history. And its continued success is a testament to the humans who have kept it going.

MISSION CONTROL

We want you to use your best judgment if the pitching array will definitely clear the top of HST.

NARRATOR

Astronauts have upgraded the telescope on five different missions since its launch.

ASTRONAUT

Hubble has arrived on board Atlantis. Okay, here we go.

NARRATOR

The last visit to Hubble was in 2009. Astronauts needed to replace the wide field camera and install and repair spectrographs that could help peer into black holes and analyze the atmospheres of distant planets. As on past missions, ingenuity saves the day.

MIKE MASSIMINO

That handrail is obstructing the attachment of the fastener/catcher plate.

NARRATOR

Astronaut Mike Massimino can't remove a handrail blocking his access to Hubble.

MASSIMINO

We couldn't get inside the thing to do the repair, and I just felt terrible. This is gonna be my contribution to astronomy, which is killing our opportunity to be able to analyze the atmospheres of planets. That darn handrail! I thought we were sunk, because I did not see any way we were gonna fix this thing.

NARRATOR

And then engineers come up with a radical idea. Break off the handle. It's a risky approach.

MASSIMINO

By yanking that thing off, by definition, we're going to have little shards of metal flying, so I put a lot of tape on the handrail to make sure that none of that stuff would get out.

DREW FEUSTEL

Houston, you ready for this?

MISSION CONTROL

Yeah, we're ready.

FEUSTEL

Okay Mass, you have a "go."

MASSIMINO

Here we go. It's off! (cheering) Disposal bag, please. The handrail was out of the way and wasn't going to be a problem anymore.

I felt really happy that we got the job done and we were leaving Hubble in good shape.

LIVIO

Hubble is working right now probably the best it has ever worked. It produces discoveries every day.

NARRATOR

The new instruments have allowed us to look deeper into the universe, revealing even more detail than before. This recent image of the Andromeda galaxy is the highest resolution Hubble photo ever taken. More than 60,000 light years across, it shows more than 100 million stars. And just this past year, a spectrograph installed on Massimino's mission analyzed the light filtering through the atmosphere of a planet 729 trillion miles from our own, and found water.

We absolutely couldn't have done this work without Hubble. It's a remarkable contribution for a 25-year-old machine.

MASSIMINO

Every one of the science instruments were eventually replaced. We don't have any of the original ones left. And that's why it's still doing its job 25 years later. We don't warranty the labor, not sure about the parts, you'd gotta check with NASA, but I think it's gonna be going for a long time.

NARRATOR

But with the Space Shuttle decommissioned in 2011, there's no way to reach Hubble. And the telescope's days are numbered.

ASTRONAUT

Hey John, this is like spacewalk number 714? Six.

NARRATOR

Astronaut John Grunsfeld visited Hubble three times, more than anyone else, and was the last human to touch the telescope in 2009.

GRUNSFELD

We'd finished all of the work that we had planned, and I was in my spacesuit and getting ready to come back into the airlock, and I gave Hubble, you know, one last tap to say goodbye, and I just felt incredibly happy that we'd had this amazing ride. And I watched it disappear off into the distance and I knew I would never see Hubble again, but we'd accomplished so much, it was just a matter of joy.

NARRATOR

Scientists hope that Hubble will work for another decade, but with every orbit, it encounters slight drag from the earth's atmosphere. The telescope will eventually fall from the sky, probably in the late 2030s. Most of Hubble with burn up, but the mirror will likely survive reentry, so NASA may send up a robot with a small rocket to help guide it safely into the ocean.

GRUNSFELD

One of the requirements for the mission that we flew in 2009 was to install an adapter on the bottom of the Hubble Space Telescope so that a future mission could dock with it so that at the end of Hubble's life, we could send it into the atmosphere so that it would re-enter over a known place on Earth.

NARRATOR

But before Hubble de-orbits, NASA is planning to launch an even larger telescope called the James Webb. It has a foldable mirror three times larger than Hubble's and will be sent to an orbit beyond the moon. But it will be hard to live up to the legacy of Hubble.

MOUNTAIN

The Hubble Space Telescope is probably the most scientifically productive instrument in history. Before the Hubble was launched, we didn't actually know the age of the universe. The Hubble just sorted that question out-- bang! We had never seen black holes before.

After Hubble, we know that every single galaxy has a black hole. We knew that when stars finish their life scale, they form planetary nebulae. Hubble just catalogued every single type of planetary nebulae. And then it caught supernovae blowing up.

We had no idea the universe was filled with dark energy. We didn't even know that was possible. We've seen into the depths where stars are formed. We can actually see the formation of planetary systems.

We knew that theoretically-- we can now see all of that stuff. So you just tick off all of those discoveries and our whole worldview is just changed. The human desire is to find out who we are. Are we alone?

Where did we come from? How did we get here? These questions probably will outlive all of us. But I think Hubble has been very important in making progress toward these answers.

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