NASA announced the termination of the mission of the Kepler space Observatory, almost 10 years after its launch.
During its nine-year mission, Kepler found more than 2,600 planets orbiting stars outside the solar system -including many with the potential for harboring life.
"Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm", Zurbuchen said.
Though Kepler will no longer collect any more data, there's still plenty of images for NASA and other scientists to examine.
Kepler was NASA's first planet-hunting mission, and it opened our eyes to the diversity of planets that exist in our galaxy and elsewhere. "Imagine what life might be like on such planets".
"Because of Kepler, what we think about our place in the universe has changed", said Hertz.
Thanks to Kepler's data, which was all safely beamed back to Earth before the end of the mission, we now know that planets are, in fact, exceedingly common.
"But what was just as awesome to me was the implications, contacts, and conversations I had over the years with others about religion, life, the universe, and our home planet Earth", Howell added.
Goodbye, Kepler. And though you may be drifting in the dark tens of millions of miles away from your homeworld, you showed that the cosmos may not be so lonely, and your contributions will not be forgotten.
The spacecraft's camera was not created to take pictures like other space telescopes.
Bill Borucki, the mission's retired principal investigator, compared the task to "trying to detect a flea crawling across a vehicle headlight when the auto was 100 miles away". The star system is oriented edge-on, as seen by Kepler, such that both planets cross in front, or transit, their star, named Kepler-9.
The $700 million mission even helped to uncover previous year a solar system with eight planets, just like ours. After the failure of a second gyroscope that kept the spacecraft steady in 2013, clever engineers found a way to use solar pressure to keep the spacecraft temporarily pointed in a desired direction.
Astronomers were dazzled by the planets it found, including Kepler-22b, probably a water world between the size of Earth and Neptune. Scientists knew this day was coming, having first revealed the low-fuel state to the public this past summer. Two weeks ago, it finally exhausted the last of its propellant. The sequence of commands for doing so has been transmitted to the spacecraft, awaiting a final command from the ground to run them.
"In the end, we didn't have a drop of fuel left for anything else", said Charlie Sobeck, project system engineer. But the telescope has now run out of the fuel needed for further operations, leading to its retirement. "While this may be a sad event, we're by no means unhappy with the performance of this marvelous machine".
Dotson gave Kepler a more personal tribute.
Jessie Dotson, Kepler project scientist at NASA's Ames Research Center, said, "I guess I feel like it was the little spacecraft that could". "It always did everything we asked of it, and sometimes more".
And those discoveries have helped shape future missions. TESS, the Transiting Exoplanet Survey Satellite, launched in April and is the newest planet hunter for NASA. In its short life, Kepler has discovered 70 percent of the 3,750 exoplanets known to date.