HAT-p-7b and the Grail quest – With Jon Jenkins
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.
Let the games begin! Starlight is falling on our detectors, so now hopefully it is only a matter of time before the remaining hurdles are jumped and the Kepler mission reports the first Earth-sized planets. This could prove an historic juncture for our sense of our place in the Universe. There will need to be some patience; the first planets we find will again be “hot jupiters” (because they are so easy). I’m predicting that the first terrestrial planets announced in a habitable zone will be around the small cool stars that are the most common in our Galaxy. That is again because those are the easiest sort for Kepler to detect. It may be a year before such an announcement. Kudos to all the team members who produced a working spacecraft, and got it into the right place and condition!
We popped the cork on the champagne about 15 minutes past 7 pm PDT after watching the breathtaking signature of the dust cover release in the Doppler residuals at DSS 26 (Goldstone) and in the spacecraft telemetry. There was quite a “twang” when it happened and we saw the reaction wheels spin up to counter the nudge the departing cover imparted to the photometer and we saw that the Fine Guidance Sensors are responding to starlight entering the barrel of the photometer. Now our real work begins in earnest!
We had our “first light” already with some sunlight making it in around the dust cover, but found a different attitude at which almost no light entered the telescope so that we could get a good dark frame for comparison with preflight test, and that can be used to formulate some of our calibration products. In retrospect, it’s nice to see that all 42 science CCDs and 4 Fine Guidance Sensor CCDs are responding to light as well as behaving as expected in dark frames.
As I write these words Kepler has still its sleep mask on and has been, in the last days, dreaming with the future view, with the wonders waiting in the distance, in some sort of REM as calibration tests take place.
