The Hubble has produced images like nothing ever seen before, as much art as science, visions of a universe more violent and fantastic than anyone had dared to imagine. It's sent back everything from razor-sharp views of the planets in our own solar system, to the vast stellar nurseries where stars and planets are born. Some show us the explosive outbursts of dying suns; others the swirling masses of stars that make up the galaxies.
But Hubble isn't just giving us extraordinary pictures. It's helping astronomers unlock the secrets of the universe. Dr. Bruce Margon, associate director for science for the Hubble Space Telescope, says of its significance: "Generations of humans have gone by with absolutely no clue about how the universe started. When my father went to school, no matter how smart he was, or how smart his teachers were, nobody had a clue how old was the universe. How were atoms made? How are stars formed? No one knew."
The Hubble Space Telescope is the size of a Greyhound bus. It weighs 10 tons and flies 400 miles above the Earth, moving five miles a second. Its cameras and scientific instruments are so sophisticated, they can capture light that began traveling through space more than 13 billion years ago. By the time that light finally enters the telescope and is transformed into an image, the picture it shows is of the universe as it was back when the light began its journey, in the unimaginably distant past. In effect, the telescope acts as a time machine.
"When we look back in time, using Hubble, we can see the universe, how it looked when it was less than a billion years old," says Dr. Mario Livio, the head of the science division for the Hubble. "And we can see what galaxies looked back then when they were the building blocks of today's galaxies."
Margon says this is important, "because we want to understand our origins. I mean, it's a very fundamental thing."
The urge is so fundamental that back in 1977, Congress approved $450 million to construct a telescope that would have an unobstructed view of the universe from above the Earth's atmosphere. It was named after Dr. Edwin Hubble, an American astronomer who, back in the 1920s, discovered that the universe is expanding.
The Hubble Space Telescope didn't get off the ground right away. First technical problems, and then the Challenger disaster, delayed launch until 1990, adding $1 billion to the price tag. When it finally did go up, Hubble was described as the most perfect telescope ever built, with the most perfect mirror.
When the first pictures came back, it was a perfect disaster. A tiny flaw in the mirror produced pictures that were out of focus, and Hubble's trouble was a front-page national embarrassment. Many people believed that NASA's future depended on whether they could fix it.
Three years later, seven astronauts were sent to repair the telescope. A lot was riding on the mission. Five spacewalks were required to perform a series of necessary repairs, including installing a new camera. On the ground, everyone waited to see if the repairs worked. They did, and Hubble was back in business.
Over the next few months, Hubble confirmed the existence of black holes. It also gave astronomers a live, close-up view as chunks of a comet crashed into Jupiter. A year later, Hubble focused its camera on a tiny spot in space for 10 days, just to see if anything was there.
There was. One picture it took revealed at least 1,500 separate galaxies, many of them farther away than ever seen before. Astronomers call it the Hubble Deep Field.
"The Hubble Deep Field is one of the very first times in astronomy where we have looked far enough away, and therefore far back enough in time, that things have started to look different," says Margon. "Instead of seeing sort of sedate, calm, pinwheels of galaxies, we see fragments, and sort of little angry wisps that we think are the beginnings of today's universe."
Until a few years ago, it was the conventional wisdom that the expansion of the universe that began with the big bang was slowing down. Dr. Ed Weiler, the head of science for NASA and the person in charge of the Hubble, says that in fact, it's speeding up. "It means that we don't understand gravity," he says. "This implies there's some negative energy force, some anti-gravity, that's actually pushing things apart. We don't understand it. It's not supposed to be there." He says it's something that wasn't known before Hubble.
According to Livio, the discovery that the expansion of the universe is accelerating flies in the face of what everyone thought was happening. He says it is one of the most amazing and important discoveries in the history of science.
He explains: "Suppose I'll take my keys from here, and I throw them up. They come back to my hand. Why did that happen? The gravity of the Earth was able to slow these keys down, and then finally even reverse the motion. So what we naturally thought was that this expansion ought to slow down in the same way as these keys slow down. What we discovered is that this expansion is, in fact, speeding up, accelerating. It would be like, I throw these keys up, and instead of falling back into my hand, they actually speed up upwards."
This extraordinary phenomenon was confirmed by a 32-year-old astrophysicist, Dr. Adam Riess. Riess' calculations on an exploding star in a small section of the Hubble deep field confirm that the universe has picked up speed.
One astronomer says that many years from now, our direct descendants won't see the sky as we see it today. It will appear as though we are sort of alone on an island, because all the lights around us will blink out.
This knowledge from Hubble doesn't come cheap. So far, it's cost the United States nearly $7 billion, with an annual operating budget of $250 million. This pays for the technicians who control and monitor the satellite, and the scientists who analyze its data at the Space Telescope Science Institute in Baltimore. It also pays for the engineers at the Goddard Space Flight Center who design the tools, equipment and procedures the astronauts use to upgrade Hubble and keep it running smoothly.
Maintenance is a challenge, since Hubble can't come into the garage for repairs. It took engineers months to figure out the procedures to replace, or change out, Hubble's power supply. The operation, completed in 2002, took almost four-and-a-half hours. It was the most complex maintenance job ever performed in space. Without power, there was no way to heat the telescope or monitor its instruments. On the ground, the engineers weren't sure Hubble would survive the deep freeze of space until power was successfully restored.
At a time when NASA's other programs rarely make headlines, Hubble does. And it's the pictures that have captured the public's imagination. Livio thinks the hype is justified. "I think that Hubble has been one of the most fantastic experiments there has been," he says. "I mean, I will go so far as to argue that the Hubble images are in some sense the most fantastic artworks of our time.
The man responsible for putting together those artworks is a NASA imaging specialist, Zoltan Levay. He uses scientific data to apply color to Hubble's black and white images. "We do adjust the color a little bit," he explains. "Partly just so it looks better, and partly so it also imparts the information that we'd like to get across." He says these are not, however, works of fiction. "It's a representation of reality, just as any photograph is not a literal reality, but a representation of reality."
On some nights in the South, the Hubble is actually visible from the ground. The orbiting observatory has become a cultural icon. The pictures it takes are so compelling, they've been used to sell everything from magazines to stamps. They're even used to sell CDs.
NASA's next mission to service Hubble was scheduled for 2004, but since the Columbia shuttle disaster earlier this year, the remaining shuttles have been grounded and the servicing mission has been postponed indefinitely.