NASA's 10 Greatest Achievements

Hubble Space Telescope, the Universe Unveiled
In 1995, the majestic spiral galaxy NGC 4414 was imaged by the Hubble Space Telescope. NASA

Before 1990, our view of space mostly came from ground-based light telescopes. The images were interesting, but not very clear, and the optics couldn't see far enough to give us the views astronomers craved. Earth's atmosphere, with all its clouds, water and gas vapors, tends to distort extraterrestrial light, so it's not terribly conducive to capturing clear images.

The solution? Put telescopes on the other side of Earth's atmosphere, where the light would travel to distant objects and bounce back unhindered. That's where the Hubble Space Telescope (HST) comes in. It wasn't the first space telescope, but the HST has proved to be one of the most scientifically important objects ever built. Named after astronomer Edwin Hubble, this telescope's made more than 1.5 million astronomical observations and looked at over 40,000 different space objects [source: Hubblesite].

Today it's still providing mankind with clear, mesmerizing images of our universe. What's more, the HST is always facilitating new discoveries. Upwards of 15,000 scientific papers have drawn on data the telescope provided [source: NASA].

To create the Hubble, NASA joined forces with the European Space Agency in the mid-1970s. Originally, the satellite was supposed to launch in 1983, but construction delays and political fallout from the 1986 Challenger disaster kept it grounded until 1990, when the Hubble finally went into orbit [source: Okolski].

The Hubble Space Telescope lets us watch the expansion of the universe in a way never before imagined. Not only does it have 10 to 20 times the resolution of a typical ground-based telescope, but a technological milestone made its images accessible to scientists and the general public alike. With the advent of the Internet, people could sit at home and watch the universe unfold in all hi-resolution, full-color glory. Hubble revealed the world, going out billions of light years from Earth, to anyone who cared to see it.

Today, the Hubble works in concert with other great NASA observatories to broaden our cosmic knowledge. Before the turn of the millennium, the administration sent up another space telescope, one that uses X-rays instead of visible light to capture breathtaking images of the universe.

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