1. The problem statement, all variables and given/known data Europa, a satellite of Jupiter, is believed to have a liquid ocean of water (with a possibility of life) beneath its icy surface. In planning a future mission to Europa, what is the fastest that an astronaut with legs of length 1.1m could walk on the surface of Europa? Europa is 3100 km in diameter and has a mass of 4.8*10^22 kg. 2. Relevant equations g planet = (G*Mplanet)/Rplanet^2 vmax= square root of g*r, where r is the length of the leg. 3. The attempt at a solution So I plugged in 1.1 for r, and found that g equals (6.6*4.4*10^22)/1550^2. This gave me an answer of 3.828672157·10^8 which according to Mastering Physics is wrong. Any ideas where I messed up?