Future Missions to Search for Earth-like Planets (cont.)
Eddington mission
The Eddington mission was proposed to the European Space Agency (ESA) in early 2000. It would search for and study potentially habitable planets around other stars using a 1.2-meter (47-inch) optical telescope.
Eddington would carry an optical photometer mounted on a three-axis stabilized platform, sitting far from Earth.
The mission would also study the makeup and evolution of stars.
In October, the ESA's Science Program Committee approved Eddington as part of a larger set of initiatives to be implemented between 2008 and 2013. A workshop to discuss the mission will be held June 11-15, 2001, in Spain.
Future Missions to Search for Earth-like Planets (cont.)
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.