QUESTION:
I was wondering, how does the shape of the space craft affect the flight of
the journey? Do some shapes make the journey shorter or work better? If so,
what are the shapes that work the best and why?

ANSWER from Charles Whetsel on June 26, 1997:
Until recently, most spacecraft shapes were designed based only on the
considerations regarding how to fold the spacecraft up (mainly the solar
arrays) so that it can fit in the nosecone of the launching rocket (most of
which were originally designed to be used as missiles).  Once the spacecraft
is in space, there is no air or water to contact the spacecraft, so
streamlining is usually not important (unlike airplanes and boats, on
earth).

However, both the Mars Pathfinder lander and the Mars Global Surveror
orbiter will come into contact with the Martian atmosphere after spending
many months in the cold vacuum of deep space.  The shapes of the spacecraft
do not affect how quickly the spacecraft are able to fly to Mars, but once
at Mars, the two shapes are very important in order to safely penetrate
through the Martian atmosphere (in the case of Pathfinder entry & descent)
or to be able to skim across the surface of the atmosphere again and again
in order to reduce the orbit period (in the case of Global Surveyor's
aerobraking).

Charles Whetsel
Chief Project Engineer
Mars Operations