Future Planet Hunting

Photo courtesy NASA Terrestrial Planet Finder

NASA's Chief Administrator, Daniel Goldin, has set a major goal for NASA to find Earth-like planets orbiting other stars. As we mentioned above, it is difficult to detect Earth-like planets because they are too dim to see in the glare of a parent star, and too small to have detectable effects on that star. However, NASA plans to launch a set of telescopes, called the Terrestrial Planet Finder (TPF), to aid in achieving this goal. The TPF will be an array of four optical telescopes and a combiner instrument. Each telescope in the array will detect light from the target star. The light will be combined in such a way as to cancel out the bright glare from the star, a technique known as nulling interferometry. The baseline of the array will be at least 0.6 miles (1 kilometer). Precision flying methods, which are currently being developed at NASA, will keep the array in formation.

Photo courtesy NASA Simulated results of the nulling-interferometry technique (the red arrow indicates a planet)

Once the star's light is cancelled, the infrared spectrum of the planet's light can be examined for the presence of substances in the planet's atmosphere that would indicate an earth-like environment.

Photo courtesy NASA Simulated infrared-absorption spectrum of an Earth-like planet (top) and how it could be interpreted for signs of life (bottom)

The TPF mission is in development stages, and hopefully will be launched within the next decade. Once operational, this space-based telescope system will revolutionize planet hunting and the search for life in the universe.