Kepler spaceraft problems – NASA investigates the reasons

During last contact with Kepler Space Observatory NASA engineers spotted that spacecraft remains in Emergency Mode.

Kepler telescope is deep space exploration vehicle with telescope onboard made by Ball Aerospace & Technologies. It was launched on atop of Delta II rocket on March 7, 2009, with assumed operational life at 3.5 years. Now, after 7 years of continuous service and over 120 million kilometers spacecraft seemed to work fine. During last contact performed on April 4, 2016, Kepler send data about its condition - all parameters were correct and NASA planned maneuver to change position of the Kepler towards to center of Milky Way. After six days NASA performed next communication session to send commands for starting maneuver; operators spotted that spacecraft is in the Emergency Mode and is able only to receive commands through Deep Space Network. For NASA it means that spacecraft uses more fuel than during normal flight; due the extended mission time and shrinking fuel amount remaining in tanks exiting from EM is now most important. At the moment NASA announced only that Kepler entered in Emergency Mode about 36 hours before communication attempt performed in April 7, 2016.

It is second failure of Kepler - first was linked with failure of two from four reaction wheels responsible for attitude control in 2013. It caused problems with aiming of the satellite, because without fully working attitude control, satellite is not able to perform precision maneuvers. To keep satellite operational and perform necessary maneuvers engineers from Ball Aerospace found innovative solution - they started to use solar pressure to stabilize spacecraft. To keep Kepler in stable flight with pressure of the photons, spacecraft should be always in certain angle to the Sun. Hard work of Ball Aerospace specialists brought positive results and Kepler became again fully operational. Spacecraft served well and it started its K2 mission's micro lensing observing campaign. There was only one condition of keeping spacecraft on correct course - every few months it should perform position correction to keep designated angle to Sun. Now after entering EM it is not possible and satellite could lost its stability. At the moment NASA has not confirmed if it was discovered what the reason of Kepler issues is or when problem will be solved.

Sources:
http://www.nasa.gov/feature/mission-manager-update-kepler-spacecraft-in-emergency-mode
http://www.nasa.gov/feature/ames/nasas-k2-mission-the-kepler-space-telescopes-second-chance-to-shine

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