space exploration news & perspectives

I went to bed the evening of May 13th exhausted from the long, intense campaign of commissioning the Kepler spacecraft. The long march started about a week after launch when we began to receive data from the photometer and needed to process it to verify that it was behaving as we expected and to prepare all the data products needed for nominal science operations. These included taking very special data sets to characterize the 2D bias frame of the CCDs (the image you get with no light falling on the detectors), the noise characteristics, the sky to pixel mapping, the science data compression tables, and the detailed shape of the stellar images (the Point Spread Functions) across the focal plane. We had been calculating the PSFs and getting our first science target tables together while the Combined Differential Photometric Precision (CDPP) data set was being collected during the last ten days of Commissioning. This was the first science-like data to be collected. So we had a target table in place with 52,496 targets and were compressing the 30-minute samples for each pixel of interest and storing these on board the Solid State Recorder. (During nominal science operations we collect pixel data for ~145,000 stars.) On Monday May 11 we turned the spacecraft to point the High Gain Antenna to Earth and downlinked the CDPP data set, all ten days of it, to the Deep Space Network, who transferred it through our Ground System* to the Science Operations Center at NASA Ames Research Center where we process the pixels, extract the photometric light curves and search for transiting planets. Nominal science operations commenced on May 12 and we could turn our attention to processing the CDPP data.

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