NASA has given the go ahead to a new optical telescope that will use a solar sail to orient itself. The Full-sky Astrometric Mapping Explorer (FAME) will be the first scientific spacecraft to use a solar sail. The $162 m spacecraft will determine the position, distance, motion, brightness and colour of over 40 million stars in our galactic neighbourhood. It will be launched in 2004.
Like ESA’s recent Hipparcos mission, FAME will use the parallax method to determine the stars’ positions: as the telescope and the Earth orbit the sun, the position of the stars will change slightly. The smaller the change, the further the star is from the Earth. FAME will also look in two directions at once to achieve its high accuracy.
“Astrometric observations are the foundation of almost all of astrophysics,” says Sean Urban of the US Naval Observatory and a member of the FAME team. Over the 2.5-year mission, each of the stars selected by the telescope will be scanned 950 times. The solar sail will be used to move the craft smoothly, thus avoiding frequent thruster burns and disruption to the spacecraft’s observations.
Unlike Hipparcos, FAME will be able to detect the “wobbling” of stars due to objects such as other stars, brown dwarfs, and planets twice the mass of Jupiter. The FAME team also hopes to use the telescope to look for dark matter in the Milky Way.
