Spacecraft meant to operate in both, an atmosphere & space, are typically
- Stream-lined (as in the case of the Space Shuttle, and Buran), or
- Spherical (Vostok comes to mind).
In contrast spacecraft meant to work in a vacuum may dispense with the niceties of aerodynamics. Wikipedia displays the Apollo Lunar Module in all it's functional glory.
The Voyager craft are designed to work in a vacuum, and have the appropriate shape for it.
- Are there any studies on the ideal form for a spacecraft at large velocity in vacuum?
- Would velocity be relevant to the shape?
- What velocity must technology achieve for the shape of the craft to be relevant?
Alternately the last may be rephrased to read -
Assuming the technology to achieve it becomes available (whenever that happens (+:) What kind of shape might contribute most to the craft approaching even a minimal 0.1c?