March 17, 2009

Kepler Mission Update

Kepler is now more than 1 million kilometers (620,000 miles) from Earth, drifting away at the rate of about 1 kilometer per second. The past few days have been spent collecting data from the focal-plane array on Kepler's science instrument, the photometer, at various sun angles and temperatures as part of the calibration process. The focal-plane array, which contains 42 charge-coupled devices like those in your digital camera, is where light from the telescope is focused.

Each data set is sent down to Earth, or downlinked, over the Ka-band radio at a telemetry rate of 3.44 million bits per second to the 34-meter antennas of the Deep Space Network, located in the Mojave desert of California, outside Madrid, Spain, and near Canberra, Australia. As the Earth rotates, command of the spacecraft is periodically handed over from one of these stations to the next in a carefully choreographed process. During the period of commissioning ground controllers have round-the-clock communication with Kepler; once science operations begin communication will occur only twice a week.


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