There are few greater follies than the belief that humanity belongs only to Earth.

We are creatures of dust, yes-but also of dreams, and now, of rockets. And as we peer out into the black velvet of space, two worlds whisper to us with different promises and different temptations.

One calls like a familiar lover: red, near, proud, and stubborn-Mars, the warrior planet. The other sings from the outer dark, cool and quiet beneath its icy skin-Callisto, the forgotten daughter of Jupiter, who watches the chaos of her family from afar and says nothing.

Mars is where we'll learn to live off Earth. Callisto is where we'll prove we can stay alive doing it.