NASA's Kepler mission is in the news again for multiple reasons -- as few as 461 and as many as a billion. In addition, Kepler science principal investigator William Borucki was named recipient of a prestigious award from the National Academy of Sciences.
Researchers on 7 January announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun's "habitable zone," the region in the planetary system where liquid water might exist on the surface of a planet.
Since the last Kepler catalog was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars. The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively.
The announcement at the American Astronomical Society (AAS) meeting followed the results of a Caltech study, released just a few days earlier, from which astronomers concluded that our galaxy alone contains more than 100 billion planets.
"We congratulate our Kepler colleagues, revel in their results and anticipate their future announcements -- all enabled by optics and photonics technology," said SPIE President-Elect H. Philip Stahl, attending the AAS event. "Today's discoveries, which captivate the imagination and inspire future generations, are the result of a national commitment to long-term continuing technology investments."
The Kepler space telescope identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars in search of planets that pass in front, or "transit," their host star. At least three transits are required to verify a signal as a potential planet.
Scientists analyzed more than 13,000 transit-like signals to eliminate known spacecraft instrumentation and astrophysical false positives, phenomena that masquerade as planetary candidates, to identify the potential new planets.
Stahl emphasized the years of preparation that go into a successful mission. "These exciting Kepler results are made possible by detector technology investments made over 15 years ago, which resulted in the world's largest space digital camera focal plane," he said.
The sole instrument aboard Kepler is a photometer for measuring the brightness variations of stars. It consists of the telescope, the focal plane array, and the local detector electronics. Kepler is a 0.95-meter (37-inch) aperture Schmidt-type telescope with a 1.4-meter (55-inch) primary mirror. The photometer features a focal plane array with 95 million pixels -- the largest camera NASA has ever flown in space.
Borucki (left), science principal investigator for NASA's Kepler mission at the agency's Ames Research Center at Moffett Field in California, is the recipient of the 2013 Henry Draper Medal awarded 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. He will receive the award at the NAS 150th Annual Meeting in April in Washington, DC.
Borucki was also the 2012 recipient of the SPIE George W. Goddard Award in honor of 25 years of design and development of high-precision transit photometry techniques that enabled NASA's Kepler mission to revolutionize our knowledge about the frequency and distribution of extrasolar terrestrial planets.
Launched in 2009, Kepler's mission was to study exoplanets of the Milky Way.
The complete list of Kepler planet candidates is available in an interactive table at the NASA Exoplanet Archive. The archive is funded by NASA's Exoplanet Exploration Program to collect and make public data to support the search for and characterization of exoplanets and their host stars.
Several papers on Kepler's instrumentation have been presented at SPIE astronomy conferences, including the biannual Space Telescopes and Instrumentation symposium, and are available in the SPIE Digital Library.