- Education and Science
Hubble Space Telescope - Changing Our View of the Universe
When the Hubble Space Telescope reached orbit in April, 1990, NASA and the scientific community were filled with anticipation and high hopes, but even they could not have imagined the extent to which Hubble would increase our understanding of the cosmos.
Hubble's success did not come quickly or easily, however. It would be a long and bumpy ride, filled with setbacks and disappointments. Here's a look at the Hubble Space Telescope's history and future, as well as some of Hubble's most beautiful photographs and most important discoveries.
Delays and Disappointments
NASA began seriously considering the idea of an orbiting telescope in the late 1960s. Unsuccessful efforts to fund the project continued throughout the 1970s, with the project being cancelled entirely at one point.
To make the telescope a reality, the project was scaled back, and finally reinstated, albeit with a reduced budget. In addition, NASA entered into an agreement with the European Space Agency, making the telescope a collaborative effort between the two agencies.
To extend Hubble's working life, the telescope would be designed such that servicing and upgrades in space would be possible. The plan was to use the Space Shuttle, still under development at the time, to place the telescope into orbit and perform servicing missions. For better or worse, Hubble's destiny had been intrinsically tied to that of the Space Shuttle.
The launch of the Hubble Space Telescope, originally scheduled for 1983, was delayed for years by both technical problems and budgetary issues. The telescope was still on the ground when, in 1986, NASA grounded the entire Space Shuttle fleet following the Challenger disaster. The Shuttle - Hubble's only ride into space - would not fly for another three years.
On April 24, 1990, the Hubble telescope finally made it into space, delivered by Space Shuttle Discovery. When scientists saw the first images returned by Hubble, however, they immediately realized that something was very wrong. The image quality was not at all what it should have been.
An investigation found that the telescope's main mirror had been ground to the wrong shape. After decades of political struggles, technical challenges and delayed launches, NASA had put into orbit a large, expensive telescope that could not be focused. It was a tremendous disappointment to scientists around the world, and one of the lowest points in NASA's history.
In 1993 a Shuttle mission was sent to Hubble to initiate repairs. In a series of long, complex spacewalks over a period of five days, astronauts installed new components designed to compensate for the problem in the main mirror. In essence, they gave Hubble a pair of "eyeglasses".
The mission was a complete success on two levels. Hubble could finally achieve its full potential, and NASA's reputation had been rebuilt. The mission demonstrated NASA's capacity to perform large-scale repairs and construction tasks in outer space. Public confidence in NASA had been restored, and future projects, such as the construction of a space station, now seemed feasible.
Hubble would go on to photograph more than 30,000 celestial objects, creating more than 500,000 images. In addition to having immeasurable scientific value, these spectacular images have also captured and excited the imaginations of people around the world. Hubble was not only one of the greatest scientific successes of the 20th century, it was also ultimately a huge public relations success for NASA, and for space science in general.
Amazing Images and Enormous Scientific Breakthroughs
Hubble's main claim to fame, of course, has been its spectacular images. On earth, a telescope's effectiveness is diminished by factors such as weather, atmospheric turbulence, and airglow (a phenomenon in which the atmosphere itself emits a small amount of background light). Hubble, unaffected by these conditions, can see further and with greater clarity than any earthbound telescope. Hubble can even "see" parts of the spectrum beyond the wavelengths of visible light, such as ultraviolet and near-infrared.
It is no hyperbole to state that Hubble has reshaped our conception of the vary nature of the universe. Here are just a few of the ways it has done this:
The Hubble Ultra Deep Field
The Hubble Ultra Deep Field is the result of pointing the telescope at a tiny, seemingly empty point in space for a series of exposures during 2003 and 2004. The image that was formed contains about 10,000 galaxies at various distances from earth. It is the deepest look into the universe ever created, and scientists continue to study it, formulating new theories on the creation and evolution of galaxies, and their distribution throughout the universe.
VIDEO: Hubble Ultra Deep Field in 3D:
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Seeing The Past
Looking out into space is also looking back in time. Objects outside of our solar system are so far away that it can take centuries, or even millennia, for light from those objects to reach earth. An image of an object 100 light years away, for example, shows us not how that object looks now, but how it appeared 100 years ago.
Hubble has observed objects that are over 13 billion light years from Earth, giving us a view of how the universe looked around 400 million years after the big bang. In cosmic terms, this is quite young, and it's much further into the past than had ever been seen before.
The Age of the Universe
Data from Hubble helped scientists accurately determine the rate at which the galaxy is expanding. This, in turn, helped establish the age of the universe as being between 13 to 14 billion years old. Solving this mystery, however, created an even larger one.
Scientists had expected the rate of expansion of the universe to either be constant or slowing down, but Hubble revealed that this expansion is actually speeding up. The cause for this is still unknown, but some scientists theorize that the acceleration is being caused by an unknown form of energy that exists throughout the universe. This as-yet-undiscovered form of energy is referred to as dark energy.
Astronomers have observed that large celestial objects, such as stars, galaxies, and galactic clusters, often move through space in ways that can't be explained. These objects appear to be influenced by gravitational forces beyond those which should be present.
Because gravity is related to mass, some astronomers speculate that there may be more matter in the universe than what can be seen. This unseen form of matter, known as dark matter, could be the source of the unexplained gravitational forces. Dark matter has never been proven to exist, but Hubble has returned data that supports the dark matter theory.
Super-Massive Black Holes
Hubble helped prove that super-massive black holes, millions of times more massive than our sun, exist at the center of many galaxies. Hubble also discovered a direct relationship between the size of the black hole and the shape of the galaxy, helping scientists better understand how galaxies form and evolve.
Hubble has not only aided in the discovery of planets orbiting other stars, it has made chemical analysis of the atmospheres of some of these worlds possible. In addition, the first actual photograph of a planet orbiting another star was taken by Hubble. The planet, Fomalhaut b, is named after the star Fomalhaut, which it orbits.
Hubble has also photographed discs of dust and gas that are believed to be planets in the early stages of being formed. Many such discs have been found throughout the galaxy, suggesting that planet formation may be a common event.
Our Solar System
Not all of Hubble's discoveries are millions of light years away. The Hubble telescope has advanced our understanding of our own celestial neighborhood. Astronomers can now track the paths of comets as they pass through the solar system, for example. In 1994 when the Shoemaker-Levy 9 comet collided with Jupiter, Hubble returned spectacular images of the event.
Hubble was also responsible for the demotion of Pluto to non-planet status. Pluto is quite small relative to the planets in our solar system - smaller even than earth's moon - and Hubble has revealed that there are many objects the size of Pluto, or even larger, at the edge of our solar system. Rather than classify all of these newfound objects as planets, the International Astronomical Union changed the definition of a planet, and created a new category, "dwarf planet", for these smaller objects, including Pluto.
Who Was Edwin Hubble?
The Hubble Space Telescope was named after Edwin Hubble, possibly the most important astronomer of the 20th century. Hubble completely reshaped our understanding of the universe. He proved that there are other galaxies existing outside of our own Milky Way galaxy, and he showed that the universe is expanding, which helped support a new theory known as the Big Bang theory.
Edwin Hubble was selected by Time Magazine as one of the Top 100 People of the 20th Century.
Future of the Hubble Telescope
The Hubble Telescope has been serviced five times by Space Shuttle missions over the years. Aging parts have been replaced, and Hubble should continue to operate until at least 2014. At some point after that, a mission can hopefully be devised to retrieve Hubble and return it to earth or otherwise dispose of it. This will prevent Hubble from re-entering the atmosphere and breaking up, as NASA's Upper Atmosphere Research Satellite (UARS) did in September, 2011.
The Hubble Space Telescope has truly revolutionized the field of astronomy. When its mission is over, new, more advanced space telescopes will take its place. The James Webb Space Telescope and the Advanced Technology Large-Aperture Space Telescope (ATLAST) are now being designed and built.
Just as the Hubble telescope did, these new telescopes will undoubtedly alter our understanding of the universe in ways we cannot even imagine.
Build a scale-model Hubble Telescope
Make a scale model of the Hubble Space Telescope, like the one shown here, out of paper, using easy-to-find supplies.
Free instructions can be found at Hubblesite.org.
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