Hubble Telescope Launch

The Hubble Space Telescope was carried into low Earth orbit in 1990 aboard the space shuttle Discovery, placing a large optical telescope above the distorting veil of the atmosphere. Named for the astronomer Edwin Hubble, it became one of the most productive scientific instruments ever built, reshaping our understanding of the age and expansion of the universe, the life cycles of stars, and the nature of distant galaxies. It also became a rare scientific project familiar to the general public.

The idea of an observatory in space predates the space age. In the 1940s, astronomer Lyman Spitzer argued that a telescope beyond the atmosphere would avoid the blurring and absorption that limit ground-based observation. Decades of advocacy followed, and in the 1970s NASA, working with the European Space Agency, began developing what was then called the Large Space Telescope. Funding fights, redesigns, and technical delays pushed the schedule back, and the loss of the shuttle Challenger in 1986 grounded the fleet and postponed the launch by several more years.

Hubble was finally deployed in April 1990, with a primary mirror about 2.4 meters across. Within weeks, however, the images showed a serious problem: the mirror had been ground to the wrong shape, a tiny error that caused spherical aberration and left pictures blurry. The flaw became a source of embarrassment and criticism. Investigators traced it to an error in the testing equipment used during the mirror's manufacture.

Hubble's designers had planned for astronauts to service the telescope in orbit, and that foresight saved the mission. In December 1993, a shuttle crew installed corrective optics, in effect giving the telescope eyeglasses, along with new instruments. Further servicing missions through 2009 replaced cameras, gyroscopes, and other components, extending Hubble's life and repeatedly upgrading its capabilities.

The results were extraordinary. Deep-field images revealed thousands of galaxies in tiny patches of sky that had looked nearly empty. Hubble observations helped refine the rate of the universe's expansion and contributed to the discovery that this expansion is accelerating, a finding tied to what is now called dark energy and recognized by a Nobel Prize in 2011. The telescope also studied the atmospheres of planets beyond our solar system, tracked storms on the outer planets, and documented the aftermath of a comet's collision with Jupiter in 1994.

Hubble's legacy extends beyond its data. Its vivid images of nebulae and galaxies entered popular culture, and its long career showed the value of crewed servicing and international cooperation. Its successors, notably the James Webb Space Telescope, which observes mainly in infrared, build on its work, yet Hubble has continued to operate well past its originally expected lifetime.