Science & Technology

NASA's Planet-Hunting Telescope Is Bidding Us Farewell

Earlier today, NASA announced that the Kepler space telescope would finish its mission. It's had quite the run. Kepler lasted nine years in space and discovered more than 2,300 confirmed planets outside of our solar system. That's nearly two-thirds of all the exoplanets ever found. Kepler's incredible mission may be over, but exoplanet science is just beginning.

Related Video: NASA's New Exoplanet Telescope Could Help Us Find Another Earth

This illustration depicts NASA's exoplanet hunter, the Kepler space telescope. The agency announced on Oct. 30, 2018, that Kepler has run out of fuel and is being retired within its current and safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 exoplanet discoveries.

Long Live Kepler's Data

Kepler's discoveries have changed our perception of the universe forever. We know from Kepler that rocky worlds are extremely common; before, most of the planets discovered were huge gas giants like Jupiter. We have found a multitude of planets that orbit in the habitable zone of their stars, where liquid water could exist on the surface. This made Kepler a valuable scout for future telescopes — those that can zoom in on the planets and better see what their atmospheres are made of.

We also learned a lot about operating a spacecraft in space. When Kepler launched, it had four metal reaction wheels — devices that spin and keep the spacecraft oriented in a particular direction. Eventually, with age, most of the reaction wheels failed. But NASA wasn't done with Kepler yet. Instead, the agency steadied the spacecraft using the pressure of the sun because engineers are, well, pretty smart. It was enough for Kepler to find several more planets during this new campaign, called K2.

And let's not forget, Kepler's data didn't die with the spacecraft. It's actually openly accessible to everyone who has an Internet connection. In fact, you can check out the data for yourself here. All future generations of astronomers can thus gaze at Kepler's work and come up with new scientific findings. All it takes is a little digging and a willingness to think big.

Carrying the Torch

NASA — again, employing engineers and all — knew that Kepler would die someday. The telescope lasted far past its design lifetime, so time was ticking. The agency felt Kepler's work was so noteworthy that it sent up a successor called TESS (Transiting Exoplanet Survey Satellite) earlier this year. TESS has another exoplanet mission, but it's quite different from Kepler's.

Kepler was originally designed to stare at one spot in the sky for many years. TESS will be more of a wanderer. The mission will scan different sectors of the sky in search of bright stars with planets. TESS has been in space for a few months, and it's already found planets. Best yet, TESS is designed to last longer than Kepler's original mission. The big question is funding — making sure TESS generates enough scientific findings to justify its existence.

Kepler was a boon to science, not only for the exoplanets it found but also for its testament to tenacity. In space, things break. And smart people on the ground need to figure out how to fix them. In the last few months, engineers kept Kepler scientifically operating with busted reaction wheels and absurdly low fuel levels. And there's fresh science to come shortly; Kepler's latest data, dubbed Campaign 19, has just been downloaded to Earth. Who knows what cool planets await there?

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Learn more about the effort to find planets far beyond ours in "The Planet Factory: Exoplanets and the Search for a Second Earth" by Elizabeth Tasker. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Elizabeth Howell October 30, 2018

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