Editing Space Interferometry Mission (section)

===Stellar mass===
[[Image:White dwarf-590.jpg|thumb|right|White dwarfs, imaged by NASA's Hubble Space Telescope]]
Another key aspect of SIM Lite's mission was determining the upper and lower limits of star's masses. Today, scientists understand that there are limits to how small or large a star can be. Objects that are too small lack the internal [[pressure]] to initiate [[thermonuclear fusion]], which is what causes a star to shine. These objects are known as [[brown dwarf]]s and represent the lower end of the stellar mass scale. Stars that are too large become unstable and explode in a [[supernova]].<ref name=masses>[http://planetquest.jpl.nasa.gov/SIM/simLiteScience/blackHoles/ Stars, Neutron Stars, & Black Holes] {{webarchive|url=https://web.archive.org/web/20100325134503/http://planetquest.jpl.nasa.gov/SIM/simLiteScience/blackHoles/ |date=25 March 2010 }}, NASA, SIM Lite, Jet Propulsion Laboratory. Retrieved 9 March 2010.</ref><ref name=masses2>[http://planetquest.jpl.nasa.gov/SIM/scienceMotivations/neutronStars/ Stars, Neutron Stars, & SIM Lite] {{webarchive|url=https://web.archive.org/web/20100614201119/http://planetquest.jpl.nasa.gov/SIM/scienceMotivations/neutronStars/ |date=14 June 2010 }}, NASA, SIM Lite, Jet Propulsion Laboratory. Retrieved 9 March 2010.</ref>

Part of the SIM's mission was to provide pinpoint measurements for the two extremes in stellar mass and evolution. The telescope will not be able to measure the mass of every star in the Galaxy, since there are over 200&nbsp;billion, but instead, it will take a "population census."<ref name=masses/> Through this technique, SIM will be able to output accurate masses for representative examples for nearly every star type, including brown dwarfs, hot [[white dwarf]]s, [[Red giant|red giant star]]s, and elusive [[black hole]]s.<ref name=masses/> Current space telescopes, including NASA's [[Hubble Space Telescope]], can accurately measure mass for some types of stars, but not all. Estimates put the range for stellar mass somewhere between 8% the mass of the [[Sun]] and in excess of 60&nbsp;times the mass of the Sun.<ref name=masses/><ref name=masses2/> The entire study was to focus on [[binary star]] systems, stars coupled through a mutual gravitational attraction.<ref name=masses/><ref name=masses2/>