The French national space agency, Centre National d’Etudes Spatiales (CNES), and the European Space Agency (ESA) plan to launch the COROT space telescope in June 2006. The COnvection, ROtation, and planetary Transits (COROT) spacecraft will study vibrations on nearby stars and search for rocky planets outside the solar system.
COROT’s 12-inch (30 centimeters) telescope will monitor stars’ brightness changes. A star’s brightness changes when a planet transits, or crosses in front of, the star. Starquakes — vibrations that ripple across a star’s surface — also cause a star’s brightness to change. Astronomers will use asteroseismology — the study of stars’ internal structures through observations of stellar vibrations — to determine nearby stars’ chemical compositions, masses, and ages. More importantly, the data COROT collects will be compared with Sun data collected by ESA’s Solar Heliospheric Observatory (SOHO).
COROT will also search for terrestrial, or rocky, extrasolar planets several times larger than Earth, but much smaller than Jupiter, around more than 500,000 stars. To date, the search for planets around stars outside our solar system has revealed 160 planets orbiting main sequence stars — those undergoing hydrogen-to-helium fusion at their cores like the Sun. Most of the gas-giant extrasolar planets detected with ground-based telescopes are about the size of Jupiter. Astronomers anticipate finding between 10 and 40 earthlike planets with COROT — a first for any spacecraft — as well as a number of new gas-giant worlds.
COROT may represent the best opportunity to advance the search for extrasolar earthlike planets in the foreseeable future. Budget cuts at NASA have all but eliminated science missions with such goals. In February, NASA’s fiscal year 2007 budget proposal included the cancellation of its Terrestrial Planet Finder (TPF) — a proposed mission to study extrasolar planets and whether they might be suitable for life to evolve — as well as a 3-year delay of its SIM PlanetQuest (SIM) — a space interferometry mission intended to survey about 100 nearby stars for potentially habitable planets.
NASA’s proposed budget cuts have met with staunch resistance, so much so that Congressional hearings are set for March 30 to review them. However, NASA Administrator Mike Griffin’s acknowledgement that “science and exploration are each paying to help complete our pre-existing obligations to the space station and the space shuttle” doesn’t leave much hope that TPF or SIM funding will be restored. Given NASA’s current budget woes, COROT’s mission to search for other Earth-like worlds could make it the forerunner in extrasolar planet science.
CNES and ESA plan to launch COROT using Russia’s Soyuz-Fregat launcher in Baikonur, Kazakhstan. Once the space telescope settles into a polar circular orbit 514 miles (827 km) above Earth, the spacecraft will perform continuous observations in two regions of the sky for at least 150 days of its 2½-year mission.