The exoplanet-hunter of NASA has retired.

NASA made an announcement about the retirement of the Kepler Space Telescope on 30^th October. The fact that the spacecraft has run out of fuel was the reason which prompted this disappointing decision. This extraordinary mission explored deep space for about 9 years and discovered more than 2,600 exoplanets during its journey. Quite a lot of these exoplanets are considered potential candidates for harboring life. The authorities at NASA decided to retire it within its current orbit as it was at a safe distance from the Earth. Thomas Zurbuchen, an Associate Administrator of NASA’s Science Mission Directorate, praised the mission and its accomplishments in the following words:

“As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond. 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. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars.”

Kepler was launched on 7^th March 2009 with the primary purpose of finding Earth-sized planets around other stars of our galaxy. It was designed to survey our portion of the Milky Way in quest of some Earth-sized planets that lie in or around the habitable zones of their parent stars. The working principle of the Kepler Space Telescope was based on a single, scientific instrument called Photometer. It was fitted on the largest digital camera that was ever sent to space at that time and had the ability to continually monitor the brightness of 150,000 main sequence stars in a fixed field of view.

The variations in brightness due to passing planets led to all the discoveries of the Kepler. Researchers selected a star-studded patch of the sky in the constellation of Cygnus for original positioning of the telescope. Leslie Livesay, the Director for Astronomy and Physics at the Jet Propulsion Laboratory who was serving as the Project Manager of the Kepler Mission during the development phase, talked about the innovative design of the telescope by saying,

“The Kepler mission was based on a very innovative design. It was an extremely clever approach to doing this kind of science. There were definitely challenges, but Kepler had an extremely talented team of scientists and engineers who overcame them.”

According to a recent analysis of the discoveries Kepler made, 20-50% of the stars that we see in the night sky have Earth-sized planets in their habitable zones. Scientists believe that many of them may have a rocky core just like our planet. The most common size of planets found by Kepler is not present in our solar system. The size of these planets lie between the size of Earth and Neptune and we need to know a lot more about those worlds for their detailed understanding. The data gathered by Kepler also revealed that our nature often produces jam-packed planetary systems. In some cases, the number of planets around a central star are so much that our own inner solar system looks sparse by comparison. William Borucki, the Principal Investigator of the Kepler Space Mission at the time of its launch, said,

“When we started conceiving this mission 35 years ago, we didn’t know of a single planet outside our solar system. Now that we know planets are everywhere, Kepler has set us on a new course that’s full of promise for future generations to explore our galaxy.”

All the research made by the Kepler Space Telescope has helped researchers to make significant progress in some other fields of astronomy including the history of the Milky Way and the expansion rate of the universe. Just before the end of its journey, Kepler was pushed to its limits for completing some multiple observation campaigns and downloading valuable data. Scientists believe that the data provided by Kepler will continue to offer more discoveries for the next decade or so despite the retirement of the telescope. Jessie Dotson, a Project Scientist of Kepler, referred to that in the following words:

“We know the spacecraft’s retirement isn’t the end of Kepler’s discoveries. I’m excited about the diverse discoveries that are yet to come from our data and how future missions will build upon Kepler’s results.”