25 Years of the Hubble Space Telescope

Hubble_in_free_orbit

This week NASA is celebrating a quarter century of discoveries from one of the most revolutionary scientific instruments of all time, the Hubble Space Telescope. Launched into orbit aboard the Space Shuttle Discovery on April 25, 1990, the Hubble changed our understanding of the age of the universe, the evolution of galaxies and the expansion of space itself. Along the way it has had the equivalent of knee and hip replacement surgery: Five times, astronauts on the space shuttle paid a visit to swap out old batteries and install new instruments. Hubble’s fate, however, is uncertain. The Hubble was designed to be serviced by the space shuttle, but the space shuttle fleet was retired in 2011, and the Hubble hasn’t had a repair job since 2009. At some point, under the laws of entropy that dominate the cosmos, the Hubble will begin to deteriorate.

Hubble’s unique advantage is that it is orbiting the Earth about 340 miles above the surface, significantly higher than the International Space Station, which means both crystal-clear images as well as access to parts of the electromagnetic spectrum that are not available from the ground.

The 44-foot-tall Hubble orbits the Earth 15 times a day. Its 2.4-meter diameter mirror has a resolution of equivalent to shining a laser on a dime 200 miles away.

Before the Hubble, astronomers estimated the universe to be 10 billion to 20 billion years old, but Hubble indicates that it’s 13.8 billion years old. The Hubble played a key role in the stunning discovery–announced in 1998–that the expansion of the universe is accelerating. Astronomers detected this acceleration, which they attribute to a mysterious force they call “dark energy,” in part by using the Hubble to study supernovas in extremely distant galaxies.

Named for Edwin Hubble, the pioneering astronomer whose study of the expanding Universe revolutionized modern astronomy, the Hubble was conceived in the 1940s and designed in the 1970s and 1980s. The Hubble Space Telescope has revolutionized nearly every area of astronomy, from the solar system (where it watched the aftermath of comets impacting Jupiter), to the very edge of the visible universe, and it is said to have been responsible for more discoveries than any other scientific instrument in history,

The deep gaze of the Hubble offers a view into the remote past; all telescopes are time machines of sorts, gathering light emitted long ago. The Hubble can see deeper into space than anyone had anticipated when the telescope was first designed. Before Hubble, we didn’t know how many galaxies there are in the universe, astronomers calculated perhaps tens of billions of galaxies, but now, thanks to the Hubble, scientists can say there are roughly 200 billion.

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Hubble should keep doing good science at least until 2020 and eventually deteriorate until it reenters the atmosphere around 2037. That might mean the Hubble would overlap for a couple of years with the operations of the Webb Space Telescope which is scheduled for launch in late 2018.

The Hubble has changed our very sense of the universe we live in, and it continues to provide views of cosmic wonders never before seen.  In commemoration of 2015’s 25th anniversary of the HST, the Pennington Planetarium at the Louisiana Art & Science Museum has on display 25 of the most intriguing images taken by HST over the past twenty-five years.

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