about 550 could be rocky planets. Nine of these orbit in their stars' habitable zone: Kepler-560b Kepler-705b Kepler-1229b Kepler-1410b Kepler-1455b Kepler-1544 b Kepler-1593b Kepler-1606b Kepler-1638b Mission status Kepler was launched in 2009. It was very successful at finding exoplanets, but failures in two of four reaction wheels crippled its extended mission in 2013. Without three functioning wheels, the telescope could not be pointed accurately. On October 30, 2018, NASA announced that the spacecraft was out of fuel and its mission was officially ended. Extension In April 2012, an independent panel of senior NASA scientists recommended that the Kepler mission be continued through 2016. According to the senior review, Kepler observations needed to continue until at least 2015 to achieve all the stated scientific goals. On November 14, 2012, NASA announced the completion of Kepler's primary mission, and the beginning of its extended mission, which ended in 2018 when it ran out of fuel. Reaction wheel issues In July 2012, one of Kepler's four reaction wheels (wheel 2) failed. On May 11, 2013, a second wheel (wheel 4) failed, jeopardizing the continuation of the mission, as three wheels are necessary for its planet hunting. Kepler had not collected science data since May because it was not able to point with sufficient accuracy. On July 18 and 22 reaction wheels 4 and 2 were tested respectively; wheel 4 only rotated counter-clockwise but wheel 2 ran in both directions, albeit with significantly elevated friction levels. A further test of wheel 4 on July 25 managed to achieve bi-directional rotation. Both wheels, however, exhibited too much friction to be useful. On August 2, NASA put out a call for proposals to use the remaining capabilities of Kepler for other scientific missions. Starting on August 8, a full systems evaluation was conducted. It was determined that wheel 2 could not provide sufficient precision for scientific missions and the spacecraft was returned to a "rest" state to conserve fuel. Wheel 4 was previously ruled out because it exhibited higher friction levels than wheel 2 in previous tests. Sending astronauts to fix Kepler is not an option because it orbits the Sun and is millions of kilometers from Earth. On August 15, 2013, NASA announced that Kepler would not continue searching for planets using the transit method after attempts to resolve issues with two of the four reaction wheels failed. An engineering report was ordered to assess