Charge density/Magnitude/Electric field?

Space vehicles traveling through Earth's radiation belts can intercept a significant number of electrons. The resulting charge buildup can damage electronic components and disrupt operations. Suppose a spherical metallic satellite 1.6 m in diameter aculates -2.5 �C of charge in one orbital revolution. (a) Find the resulting surface charge density. (b) Calculate the magnitude (in N/C) of the electric field just outside the surface of the satellite, due to the surface charge.