NASA reported it has released 43 days of science data on more than 156,000 stars monitored by the Kepler space observatory, developed by the space agency to continuously monitor the brightness changes of a fixed field as part of an ongoing search for Earth-like planets outside of our solar system. By measuring tiny decreases in the brightness of stars when planets cross in front of, or transit, them, the size of the planet can be derived from the change in the star's brightness.
NASA said astronomers would use the new data to determine if orbiting planets are responsible for brightness variations in several hundred stars, which represent a range of temperatures, sizes and ages. The 28-member Kepler science team also is using ground-based telescopes and NASA's Hubble Space Telescope and Spitzer Space Telescope to perform follow-up observations on a specific set of 400 objects of interest, the space agency reported.
The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall, NASA reported, and the data from these other observations will determine which of the candidates can be identified as planets. That data will be released to the scientific community in February 2011, the agency said. "I look forward to the scientific community analyzing the data and announcing new exoplanet results in the coming months," said Lia LaPiana, Kepler's program executive at NASA headquarters in Washington.
LaPiana said without the additional information, candidates that are actual planets cannot be distinguished from false alarms, such as binary stars -- two stars that orbit each other. The size of the planetary candidates also can be only approximated until the size of the stars they orbit is determined from additional spectroscopic observations made by ground-based telescopes. NASA reported many of the stars Kepler monitors are stable, while others pulsate. Some show starspots, (similar to sunspots), and a few produce flares that NASA said would sterilize their nearest planets.
The space agency said it plans to continue conducting science operations with Kepler, named after German astronomer Johannes Kepler, until at least November 2012. "This is the most precise, nearly continuous, longest and largest data set of stellar photometry ever," said Kepler deputy principal investigator David Koch of NASA's Ames Research Center. "The results will only get better as the duration of the data set grows with time."
Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory (JPL) managed the Kepler mission development, while Ball Aerospace and Technologies developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. "The Kepler observations will tell us whether there are many stars with planets that could harbor life, or whether we might be alone in our galaxy," said the mission's science principal investigator, William Borucki of Ames.