Kepler, Hubble, and the Great Observatories: Telescopes in Space

In 2009, the National Aeronautics and Space Administration (NASA) launched the Kepler Space Telescope, the latest in a series of advanced telescopes designed to carry out their work in space rather than on the ground on Earth. There are numerous advantages to space-based telescopes, which can operate free of the various interfering and troubling elements of the Earth's atmosphere. (Some particularly sophisticated work, like monitoring X-rays, can only be done from space.) As a result, they have begun to generate an increasing amount of scientific data and, along with that data, headlines in the mainstream media.

For people with a little interest in such space news but little knowledge of NASA's increasingly intricate web of programs, however, these occasional spurts of news can be a little bit confusing. So, for your benefit, here is a quick survey of the various major space telescopes currently in operation. The next time one is mentioned in the news associated with some new photograph, you can judge the significance for yourself.

Hubble Space Telescope (1990) - hubble.nasa.gov- The Hubble telescope (HST) was the first space telescope project. Hubble works in the visual light spectrum (unlike most of its successors) and therefore has produced some of the most astonishing and famous pictures of distant galaxies and nebulae. It's also been perennially prone to equipment problems, and is the only orbiting probe to have been manually serviced by astronaut crews, operating out of the Space Shuttle. In January 2010, Hubble's latest release was an image of the farthest galaxies it has yet captured; because of the time the light takes to reach us, these are also the oldest galaxies ever seen. Hubble's picture may be portraying them as early as 900 million years after the origin of the universe. Hubble will continue generating these striking images until it is shut down and deorbited in 2014.

Compton Gamma Ray Observatory (1991) - cossc.gsfc.nasa.gov - When NASA launched the Compton telescope, they decided to retroactively name Hubble the first in a series of massive orbital telescope projects, the so-called "Great Observatories," of which Compton was the second. Compton carried out unprecedented research in the upper electromagnetic spectrum, not covered by other telescopes. However, it was the shortest-lived of the major telescopes. Compton was deorbited in 2000 after its gyroscopes failed, rendering it unstable and prone to increasing navigation problems. Without the mechanical breakdown, in theory it could still be in orbit. Today, what's left of Compton is lying somewhere at the bottom of the Pacific Ocean.

Chandra X-Ray Observatory (1999) - chandra.harvard.edu - The third installment in NASA's Great Observatory project, Chandra's X-ray imaging was the first project which not only could be done better in space, but in fact can be done only in space. Whereas the next telescope, Spitzer, studies stars and galaxies as they come to life, Chandra studies astronomical death: galactic collisions, black holes, neutron stars, and pulsars. Its mission continues.

Spitzer Space Telescope (2003) - http://spitzer.caltech.edu/ - Spitzer was the final project in NASA's Great Observatories program. Spitzer, like the upcoming Webb, is an infrared telescope. Recently, its helium fuel supply was depleted. As a result, it can no longer cool its onboard equipment, which are gradually heating up and breaking down. The surviving functions continue to be used at reduced effectiveness in what has become known as the "Spitzer Warm Mission." Spitzer used to specialize in imaging new stars and young galaxies as they formed. Now, however, it is unlikely to yield new, exciting reports in the popular media.

Kepler Space Telescope (2009) - www.kepler.gov - Kepler is the most recent operational telescope, launched in 2009, and is the subject of high hopes among planet-searchers and those hoping to find evidence of other planets where life might be viable. Unlike other telescopes, Kepler was specifically designed to find planets orbiting distant stars, and so far it is already doing so: five were announced just this week. Some of them, strangely, are hotter than scientists believed planets could ever be. Kepler's mission continues and is expected to yield further groundbreaking results. Theoretically, the telescope is powerful enough to locate Earth-sized planets orbiting other stars; however, if there are any Earth-like planets out there, it will take several years to confirm these discoveries because of their comparatively long orbital periods.

James Webb Space Telescope (2014) - jwst.nasa.gov - When it's launched, probably in 2014, the Webb will be the newest telescope. Although it's intended to replace the aging Hubble, the Webb telescope will also be much more specialized, taking in only infrared light using a specialized, massive lens -- much bigger than existing orbiting equipment like Hubble. To carry out its sensitive work, Webb will actually be in solar orbit rather than Earth orbit, at a special point known as the Lagrange point -- an orbit that will always put the Earth between the telescope and the sun to protect its delicate equipment.

Beyond 2014, there are a variety of advanced space probes being planned to study new theoretical physics concepts like dark energy and dark matter. Most of these are too far enough to be worth writing about yet, though, as the specifics of their missions will undoubtedly change over the coming decade. There are also quite a number of smaller and less ambitious space telescopes currently in operation, which were not surveyed here.