Searching for Life in Other Solar Systems; Magnificent Cosmos; Scientific American Presents; by Angel, Woolf; 4 Page(s)

The search for extraterrestrial life can now be extended to planets outside our solar system. After years of looking, astronomers have turned up evidence of giant planets orbiting several distant stars similar to our sun. Smaller planets around these and other stars may have evolved living organisms. Finding extraterrestrial life may seem a Herculean task, but a space telescope mission called the Terrestrial Planet Finder, which the National Aeronautics and Space Administration plans to start in 2005, aims to locate such planets and search for evidence of life-forms, such as the primitive ones on Earth.

The largest and most powerful telescope now in space, the Hubble Space Telescope, can just make out mountains on Mars at 30 kilometers (19 miles). Pictures sharp enough to display geologic features of planets around other stars would require an array of space telescopes the size of the U.S. But pictures of Earth do not reveal the presence of life unless they are taken at very high resolution. Such images could be obtained with unmanned spacecraft sent to other solar systems, but the huge distance between Earth and any other planet makes this approach impractical.