by Jim Fanson, Kepler, JPL Project Manager
Kepler Mission Manager Update
Scientists have analyzed "dark" calibration data taken by Kepler with its dust cover on, and have concluded that the telescope's focal-plane array, the area where light is focused, is behaving as expected. No additional dark calibration is required. The results agree with ground tests performed in a simulated space environment, once the effect of cosmic rays and solar protons are taken into account. Cosmic rays and solar protons are largely blocked from reaching Earth's surface by our planet's atmosphere and magnetic field, and therefore don't show up in the ground-test data. The next major step in commissioning is the release of the dust cover, which will permit starlight to enter the telescope.
On Monday, March 23, Kepler entered a limited-activity safe mode. Safe mode involves the spacecraft automatically pointing its solar arrays directly at the sun, powering off its photometer instrument, and rotating very slowly about the spacecraft-sun line. Engineers have full control of the spacecraft and are investigating the possible cause of its entry into safe mode. Once a better understanding of the cause is reached, the operations team will prepare the spacecraft to resume commissioning activities.