- About PSI
This map of neutron counting data at Ceres was acquired by Dawn's gamma ray and neutron detector (GRaND) instrument. The data comes from Dawn's low-altitude mapping orbit at Ceres, which is at a distance of 240 miles (385 kilometers) from the dwarf planet. The color scale of this map is from blue (lowest) to red (highest). This data, based on number of neutrons detected per second, reflects the concentration of hydrogen in the upper yard (meter) of regolith. Counts decrease with increasing hydrogen concentration. A portion of the northern hemisphere of Ceres is shown. The pole is marked with a white line. The longitude is centered on Occator Crater. Lower neutron counts near the pole suggest the presence of water ice within about a yard (meter) of the surface at high latitudes.