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The Hubble Space Telescope after it had been serviced by the space shuttle Discovery in 1997.

The Hubble Telescope: From First Launch to Last Repair Mission

November 10, 2009
by Haley A. Lovett
In its 20 years, the Hubble Space Telescope has transformed the way astronomers view the universe. It introduced people on Earth to far-off galaxies, and revealed new information to help scientists understand how the universe began, and what is in store for the future.

A View Above the Clouds: How the Hubble Telescope Came to Be

Before orbiting observatories such as the Copernicus satellite and the Orbiting Astronomical Observatory, astronomers were limited in their view of space. The Earth’s atmosphere distorts the view of the stars and limits the entrance of radiation waves to the Earth’s surface; this prevents some ultraviolet and x-rays from passing through the atmosphere, which is good for people, but bad for astronomy.

Orbiting satellites, as they are beyond the Earth’s atmosphere, can clearly observe all wave emissions from space, though the early satellites did not have very advanced data collection tools and couldn't be easily repaired. Both NASA and the European Space Agency wanted a more sophisticated satellite that could be repaired and used for years. In 1975, they began working on developing the Hubble Space Telescope.

The name Hubble comes from the famous astronomer Edwin Hubble. Born on Nov. 29, 1889, Hubble was first a well-known boxer and then a lawyer before he returned to science and worked at the Mount Wilson Observatory in California. In his studies as an astronomer, he proved that there were galaxies outside the Milky Way. He also proved what is known as “Hubble’s constant,” which says that the farther apart galaxies are from each other, the faster they move.

Originally set to launch in October 1986, the launch of the Hubble telescope was delayed for two years because of the explosion of the space shuttle Challenger. The shuttle that would put the Hubble into orbit finally launched on April 24, 1990.

Images and Discoveries From the Hubble Telescope

According to NASA, the Hubble Space Telescope orbits the Earth once every 96 minutes. The satellite has now orbited Earth more than 100,000 times since it was put into orbit. Although the Hubble Telescope isn't large compared with many of the enormous ground-based telescopes, its ability to see a wide range of light wavelengths (from ultraviolet to near-infrared) and the fact that it is above the interference of the Earth’s atmosphere, make it a prime instrument for gathering data and images from distant places in the universe.

Perhaps one of the most significant discoveries of the Hubble Telescope is that it has helped determine the age of the universe to be about 13 or 14 billion years old. Another important discovery from the Hubble Telescope happened after two teams of scientists released findings that seemed to show that the expansion of the universe was speeding up, not slowing down as people had once thought. Others in the astronomy community felt that there was probably something wrong with the observations, so the groups turned to the Hubble Telescope to gather more information and eventually showed that the universe did in fact appear to be speeding up.

The HubblesSite explains that this phenomenon occurred because of something called “dark matter,” and that as galaxies got farther away from each other, “dark matter” seemed to take over the gravitational pull that had once slowed down their movement and began to push them away at a faster rate.

Recently, the Hubble Telescope played a key role in the discovery of a new planet outside our own solar system, Fomalhaut b. Although most extra-solar planetary discovery occurs by deduction, meaning that astronomers don't actually see the planet but instead observe its gravitational affect on other objects nearby, Fomalhaut b was actually observed using the Hubble Telescope.

A 2005 article from National Geographic details some of the most incredible discoveries made by the Hubble Telescope at that time. Some of the findings include the views of the deep and ancient universe, the chemical makeup of extra-solar planets’ atmospheres, the confirmation of black holes, and information about the formation of planets, the location of quasars and gamma ray explosions.

Along with its amazing discoveries, the Hubble Space Telescope has brought beautiful and fascinating pictures of far away galaxies and the edges of the universe to the people of Earth. The Hubble Heritage Project hosts some of the most captivating photos taken by the satellite, from close up views of planets in our own solar system, to images that capture the gas clouds at the far reaches of the universe.

Repairing Hubble: From the First to the Last Repair Mission

One of the goals of the scientists who built the Hubble Space Telescope was to make it capable of receiving repairs and maintenance throughout its lifetime. They didn’t have to wait long after its launch to find a reason to do so.

The first problems with the Hubble were discovered soon after its launch in 1990. The pictures being returned to Earth from the telescope were a bit fuzzy, and scientists realized that it was due to a small imperfection in the mirror on the telescope. In 1993, the first service mission was launched to fix the mirror and replace a few cameras onboard. That repair mission was soon followed by service mission 2, service mission 3A and service mission 3B—all missions that replaced malfunctioning or poorly performing instruments with more advanced technologies.

Service Mission 4, the last ever mission to repair the camera, was set to visit the Hubble in October 2008, but just a few weeks before the mission the telescope experienced a major malfunction that stopped data from being transferred back to Earth. Scientists working on the project were relieved that the malfunction happened when it did, and not after the other repairs had been done.

Service Mission 4 was completed in May of 2009, scientists replaced batteries, repaired borken instruments, installed new gyroscopes to maintain the telescope's stability, put in a new imaging camera, and a new spectrograph in hopes of keeping the Hubble in working order until 2014 when it will retire. 

After the service mission was complete, Hubble went dark for months so that scientists could properly adjust all of the new equipment on board. In September of 2009, after being properly calibrated, Hubble once again began sending never-before-seen images back to Earth. Scientists hope to use Hubble to look even deeper into space to potentially unlock the mysteries of the universe's oldest galaxies.

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