14 DAY TRIAL // The Hubble Space Telescope has just turned 22 in low-Earth orbit. Launched back on April 24, 1990, at 8:35 EDT (1235 GMT), the observatory is one of the most iconic scientific instruments in the world, having captured the imagination and fascination of several generations with its images.
Along with the Chandra X-ray Observatory, the infrared Spitzer Space Telescope and the now-defunct Compton Gamma Ray Observatory, Hubble is part of NASA's Great Observatories series of telescopes.
It was deployed to space during the STS-31 mission, which was carried out by space shuttle Discovery. The orbiter launched from the Launch Pad 39B facility at the NASA Kennedy Space Center, in Florida.
Even though it is now known as one of the most successful missions NASA and the European Space Agency conducted, Hubble did not have an easy life. An error plaguing its main mirror – discovered only after the launch – compromised its capabilities.
Fortunately, this is the only observatory in existence today that was designed to be repaired in space. Between 1993 and 2002, four space shuttle missions were conducted to repair the spacecraft, its instruments and various other components.
A fifth mission was authorized by former NASA Administrator Mike Griffin in 2009, and was carried out using the space shuttle Atlantis. The upgrades installed two years ago will allow the observatory to remain airborne for several years. Deorbiting is scheduled to occur between 2013 and 2021.
The importance of the discoveries Hubble made cannot be overstated. In addition to helping solve a number of long-standing astronomical mysteries, it also managed to raise some interesting questions of its own, which required the formulation of new theories to explain.
One of its main missions was to constrain the value of the Hubble constant, which indicates the rate at which the Universe is expanding. The observatory was also the first to indicate that this expansion may be accelerating, by studying distant supernova explosions.
It also demonstrated conclusively that most galactic cores feature black holes. This had been proposed decades before its launch, but the theories held that only some galaxies featured the dark behemoths.
Hubble also identified a number of protoplanetary disks in the Orion Nebula, found indications of extrasolar planets, and found the optical counterparts of gamma-ray bursts. Its Deep Field and Ultra-Deep Field studies peered farther away into the origins of the Universe than any investigation before or since.
In addition to its scientific contributions, Hubble also represents the most popular and renowned tool connecting the astronomical community to the general public. Science books around the world feature its high-resolution images, revealing the beauty of space to children.
Hubble will be replaced by the NASA James Webb Space Telescope - the most ambitious observatory project ever designed - in 2018, at the earliest.