If this bears a certain familiarity to the
Discovery from 2001: a Space Odyssey, that's because the basic
shape was one favoured by Arthur C. Clarke since he started writing
about space travel over half a century ago. This is what he
called the "gamma" or dumbbell shaped spaceship. One sphere
is the habitat module for the crew and the other sphere
contains the atomic motors needed to drive the craft to edge of the
Solar System. The stick in the middle is to put some distance
between the crew and the atomic reactor in hopes of keeping two-headed
offspring to a minimum.
When 2001 was filming, Kubrick went
through dozens of different spaceship designs. There were fat
ones, thin ones, wedge-shaped ones, but in the end, the winner was the
dumbbell. You can't beat a classic.