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Science Objectives
Science Overview
 SIM Lite’s broad range of science investigations will span the areas of exoplanet research, cosmology and stellar astrophysics. The SIM Lite Astrometric Observatory is a 6-meter Michelson stellar interferometer. It will be launched into an Earth-trailing solar orbit where it will operate for a mission lifetime of five years. With SIM Lite, astrometry, the most ancient discipline in astronomy, will be poised to answer the science questions of the 21st century:
Exoplanet research has become a rich field for observers and theoreticians alike. The number of known exoplanets now numbers over 300, predominantly gas giants. SIM Lite will search for Earth-like planets, examining over 60 nearby stars for evidence of habitable worlds down to one Earth mass (G. Marcy, M. Shao). In addition, SIM Lite will conduct a survey of young stars as part of a larger effort to map the birth, evolution, and architectures of planetary systems (C. Beichman).
In cosmology and physics, there is now compelling evidence that only 4 percent of the energy density in the universe can be seen directly. Of the remainder, about 22 percent is thought to be composed of dark matter, a non-baryonic material of unknown character whose presence can be inferred only from its gravitational effect on visible matter. SIM Lite will probe the nature of dark matter and its role in the formation of the Milky Way and other galaxies (S. Majewski, E. Shaya).
In the field of stellar astrophysics, SIM Lite will deliver ultra-precise measurements of stellar masses, luminosities, and ages, enabling astronomers to test stellar evolution models with heightened fidelity (T. Henry, A. Gould, B. Chaboyer, G. Worthey, A. Quirrenbach). This will strengthen the theoretical foundation for understanding cosmological galaxy evolution as we enter the era of the James Webb Space Telescope and large adaptive-optic ground-based telescopes.
In studies of active galactic nuclei, supermassive black holes have been identified as the source of their enormous energy output. But we still lack a detailed understanding of the accretion disks that surround the core and the relativistic jets that propagate away from them. SIM Lite will peer into the hearts of galactic nuclei, probing to within light-days of the massive black holes at their centers, shedding new light on this mystery (A. Wehrle, K. Johnston).
Multi-discipline studies add to the research already planned (S. Shaklan, S. Kulkarni, R. Allen). In addition, a wide variety of potential science investigations are being studied to broaden further SIM Lite's science return.
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