Kepler is NASA’s premier space observatory tasked with discovering Earth-sized planets in the milky way galaxy. Launched on March 7, 2009, Kepler surveys our corner of the Milky Way searching for earth-sized exoplanets that lie within the habitable zone of their star.
The Kepler mission intended to last 3.5 years, though additional time was needed to complete the mission, extending the end from 2012 to 2016. Unfortunately, some unforeseen events stalled the mission’s progress.
On July 14, 2012, one of the craft’s four reaction wheels necessary for data collection ceased functioning,  making it so all three wheels would need to remain reliable for the mission to continue.
The nail in the coffin pierced Kepler on May 11, 2013, when a second wheel stopped working, disabling data colletion and endangering the mission.
On May 16, 2014, NASA approved the K2 extension, a proposed solution that would utilize the disabled equipment on Kepler to detect potentially habitable planets around red dwarf stars.

As of April 1 2018, Kepler has discovered 3,758 confirmed planets in 2,808 star systems, 627 of those having multiple planetary bodies. So far the mission has lasted over 9 years and made tremendous strides in the field of exoplanet discovery. Kepler is the pioneer of exoplanet discovery, paving the way for the future of space observatory surveys of our vast cosmos.

See also The James Webb Space Telescope.

In 2020, T James Webb Space Telescope aims to augment everything we’ve ever seen out in the Cosmos. Webb will serve as the premiere space observatory, studying the history of the universe and uncovering some of its great mysteries. Webb will have the capability to survey planets to see if they can support life like here on earth and will also study the formation of the universe’s first galaxies. Exciting times lie ahead.