NEAR Magnetic Field Observations at 433 Eros: First Measurements from the Surface of an Asteroid

The magnetometer investigation aboard the NEAR-Shoemaker spacecraft has obtained extensive magnetic field observations throughout the 433 Eros environment, from distances in excess of 100,000 km to those conducted after landing on 12 February 2001. We report the apparent absence of global scale magnetization at this asteroid (H<0.005 A·m−1; natural remanent magnetization per kilogram <1.9×10−6 A·m2 ·kg−1), orders of magnitude less than the intense magnetization attributed to S-class asteroids Gaspra and Braille. The extremely low magnetization state of 433 Eros places this object significantly below the levels generally associated with LL chondrites and undifferentiated primitive bodies, challenging our current understanding of the meteorite–asteroid connection.