Kepler launched one prototype in January on a Chinese Long March 11 rocket and has a second prototype planned for launch in November on an Indian PSLV with a third prototype under construction.
Kepler launched in March 2009.
Two reaction control wheels failed on Kepler in 2013, ending the spacecraft’s primary mission and leading to the development of the K2 extended mission.
Two prior observing campaigns by Kepler were interrupted by issues related to running out of hydrazine fuel for its thrusters.
Pressure in the fuel tanks on the thrusters of Kepler is dropping, indicating that it is running low on fuel.
NASA successfully downlinked data from Kepler during the two previously interrupted observing campaigns.
The latest observational effort by Kepler, called Campaign 20, started on October 14.
NASA’s Kepler spacecraft has entered a safe mode due to running low on fuel.
During a routine communications session on October 19, controllers found that Kepler had entered a no-fuel-use sleep mode, disrupting operations.
Paul Hertz, director of NASA’s astrophysics division, states that they are not surprised if Kepler runs out of fuel soon.
Downloading data from Kepler requires reorienting the spacecraft, which is more fuel-intensive than routine observations.
Kepler uses thrusters to properly point the spacecraft, and the mission will end when hydrazine is exhausted.
The Kepler spacecraft launched in 2009 to search for exoplanets by detecting periodic dips in starlight from transits.
Kepler lost two of its four reaction wheels in 2013 and has used the spacecraft’s thrusters as an alternate control mechanism since then.
Kepler has a second of three prototype satellites from ÅAC Clyde scheduled to launch later 2018.
Based on the tests, Kepler expects to achieve a 10 Mbps downlink and 10 Mbps uplink connection with a 30-square-centimeter Phasor antenna.
Kepler is planning a constellation of 140 Ku-band satellites by 2022 to connect Internet of Things devices and serve as an in-space relay for other spacecraft using intersatellite links.
Kepler originally relied on four reaction control wheels for orientation, but two of the wheels malfunctioned by mid-2013.
NASA is monitoring the health and performance of Kepler as the exact amount of remaining fuel is difficult to measure.
Engineers revived Kepler in early August 2023 to transmit Campaign 18 data before returning it to safe mode.