The asteroid Ida has a small moon, dactyl, that orbits at a speed of 5.66 m/s in an orbit of radius 90000 m. Use those numbers to calculate Ida's mass (in scientific notation).
M = rv^2/G =[90,000 x 5.66^2] / [6.67 x 10^-11]
M = 43,226,446,776,611,694 = 4.3 x 10^16 kg - Ida's mass.
