Terrestrial Planet Finder (TPF)
The Terrestrial Planet Finder (TPF) would use an array of telescopes orbiting the Earth in formation to generate planetary pictures 100 times more detailed than those the Hubble Space Telescope could take.
TPF would use a developing technology called nulling to improve vision. Light waves from a star have crests and troughs, just like water waves. If the starlight from two separated telescopes comes together just right, the crests from one and the troughs from the other can cancel each other out, reducing or eliminating starlight. This would allow a view of planets around the star [see animation].
The goal would be to create a census of relatively nearby Earth-sized planets. TPF would study all aspects of planets: from their formation and development to their suitability as an abode for life.
The telescope would study planetary systems as far away as 50 light-years. In addition to measuring the size and temperature, instruments would reveal the relative amounts of gases like carbon dioxide, water vapor, ozone and methane, all of which would help determine whether a planet could support life, or could have supported it in the past.
TPF is targeted for launch in 2011, though it has not been funded. Before the mission can be designed, engineers still need to figure out how to control separate spacecraft flying in formation while also orbiting Earth.
