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Searching for Earths
 | | | "SIM is going to provide an answer to the question ... are there other Earths?" | | - Dr. Geoff Marcy
UC Berkeley | | | |
SIM Lite, scheduled for launch within the next decade, will be the most powerful planet-hunting space telescope ever devised. Using two separated mirrors and combining their light with a technique known as interferometry, SIM Lite will be able to detect planets as small as Earth. These are the kinds of planets that scientists believe have the most potential to support life.
Although more than 320 planets have been discovered beyond our solar system since 1995, the "holy grail" - Earthlike planets located in the habitable zone - remains beyond the reach of current telescopes.
SIM Lite will perform the first census of nearby Earth-like planets by observing the "wobble" in each parent star's apparent motion as the planet orbits, to an accuracy of one millionth of an arcsecond. That's the thickness of a nickel, viewed at the distance of the moon!
A second planet search program, called the "broad survey," will probe roughly 2,000 stars to determine the prevalence of Neptune and larger mass planets in all stellar types in our part of the galaxy.
A third component of the mission's planet-finding program consists of a search for Jupiter-mass planets around young stars.
This survey will help scientists understand the process of solar system formation, including the occurrence of "hot Jupiters" - massive planets located very close to their parent stars.
The SIM Lite study of neighboring planetary systems will set the stage for future space telescopes, like Terrestrial Planet Finder, that will be able to directly image these distant worlds, and probe their atmospheres for the signatures of life.
What makes a planet 'Earthlike?'
A major goal of SIM Lite is to search for Earthlike planets in the habitable zones of nearby stars. - Earthlike means a rocky planet large enough to retain an atmosphere, but less than 10 times the mass of Earth.
- Habitable zone is the region around the system's star where we can expect to find liquid water at the surface. If the planet is too hot, the water becomes vapor and is lost from the atmosphere. If the planet is too cold, the water freezes. Either of these conditions would make a planet very inhospitable for life.
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