Kepler Update
As of early March the Kepler spacecraft was 40 million miles from Earth and operating normally in science data collection mode. A quarterly roll was executed on January 11 after quarter 15 data collection was terminated. Quarter 16 data is now being collected. The next quarterly roll is scheduled for April 8 when the last month of quarter 16 data will be sent back to Earth and quarter 17 data collection will start.
In January an additional 461 planetary candidates were announced from the results of analysis of quarters 1 through 6. Kepler now has 2740 planet candidates with 115 confirmed as planets.
Data from quarters 1 through 12 have now been searched for planetary transits enabling detections of planets with periods up to 1 year. 18,406 transit-like signals were found and have been reported to the Exoplanet Archive. The Kepler team is now examining these events to pull out reliable planet candidates.
Since the loss of reaction wheel #2 in July of 2012, the status of the remaining three wheels has been closely monitored. In early January the team detected a friction elevation in wheel 4. This persisted through the quarterly roll on 11 Jan and for several days after. The Kepler spacecraft entered a 10 day wheel resting state on January 17 to allow an opportunity for the lubricant to redistribute itself through the wheel bearings. Kepler came out of rest successfully and restarted science data collection on January 27. No change in wheel performance was seen. The high-rate wheel performance data was downlinked as part of the routine monthly download in early March. The data revealed that in addition to the elevated friction that has been present since January, there were additional transient friction events in February, in the form of torque spikes, in reaction wheel #4. The team is still analyzing these events. Kepler is currently operating normally collecting data and continuing to watch wheel 4.
The Kepler team announced the discovery of the smallest planet yet found around a star like our sun. Dubbed Kepler-37b, the planet is slightly larger than our moon, measuring about one-third the size of Earth, which made its detection a challenge. The research team used asteroseismology, the study of the interior of distant stars, to measure the radius of the host star Kepler-37 to three percent accuracy, which translates to exceptional accuracy in the planet's size. Kepler-37 is the smallest star where this technique has been used to precisely measure a star’s size and, therefore the size of the planet.
New analysis of Kepler data from the Harvard-Smithsonian Center for Astrophysics (Fressin, F., et al. 2013, arXiv1301.0842) shows that one in six stars have an Earth-sized planet in an orbit closer than Mercury. The study concludes that since the Milky Way has about 100 billion stars, there are at least 17 billion Earth-sized worlds out there and that at least 70 percent of stars host at least one planet of any size. It is the planet-less star that is rare.
A new study from Caltech (Swift, J., et al. 2013 Astrophysical Journal, vol 764, pg 105) provides yet more evidence that planetary systems are the cosmic norm. The team made their estimate while analyzing planets orbiting a star called Kepler-32 -- planets that are representative, they say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding how most of these worlds form.
William Borucki, science principal investigator for NASA's Kepler mission at NASA's Ames Research Center at Moffett Field in California, was awarded the prestigious 2013 Henry Draper Medal by the National Academy of Sciences. Borucki is honored for his founding concept and visionary leadership during the development of Kepler, which uses transit photometry to determine the frequency and kinds of planets around other stars.