Captain Cook , the Terrestrial Planet Finder and the Search for Extraterrestrial Intelligence

Over two hundred years ago Capt. James Cook sailed upWhitsunday Passage, just a few miles where we now sit, on a voyage of astronomical observation and discovery that remains an inspiration to us all. Since the prospects of our visiting planets beyond our solar system are slim, we will have to content ourselves with searching for life using remote sensing, not sailing ships. Fortunately, a recently completed NASA study has concluded that a Terrestrial Planet Finder could be launched within a decade to detect terrestrial planets around nearby stars. A visible light coronagraph using an 8-10 m telescope, or an infrared nulling interferometer, operated on either a ∼ 40 m structure or separated spacecraft, could survey over 150 stars, looking for habitable planets and signs of primitive life. Such a mission, complemented by projects (Kepler and Eddington) that will provide statistical information on the frequency of Earth-sized planets in the habitable zone, will determine key terms in the “Drake equation” that describes the number of intelligent civilizations in the Universe. 1. Historical Introduction This conference takes place in the Whitsunday group of islands discovered on Whitsunday (June 3), 1770, by the English explorer, Capt. James Cook. Surprisingly, the stated goal of Cook’s voyage was astronomical in nature. As described in Richard Hough’s excellent biography (1997) of Capt. Cook, the story has echoes in today’s searches for other worlds. Johannes Kepler and Edmund Halley (1716) predicted that Venus would traverse across the face of the Sun in 1761 and 1769. These astronomers realized that comparing the timing of the transit from multiple locations would yield a measurement of cosmological importance, the Earth-Sun distance or Astronomical Unit (AU), then known to no better than a factor of two (Sellers, 2001; and www.dsellers.demon.co.uk/ venus/ven ch4.htm). Just as today’s scientists argued that the Hubble Space Telescope was necessary to determine the Hubble constant, and thus the scale of the Universe, so too did the astronomers of the 18 century argue for an Transits occur in pairs separated by roughly a century. The next pair will happen on June 8, 2004, and June 5, 2012. See The Transit of Venus (Sellers , 2001).