Mechanics. The only time you need a ton of fuel is escaping Earth's orbit. After that, you only need enough to keep the astronaut from dying, and enough power to keep the other mechanical basics going. You don't need much thrust in space to keep moving. And then re-entry is simply letting gravity do the work, not fuel.

Plus, they can't seem to grasp the actual launch craft size from what they see on the telly. I knew, theoretically, that it wasn't a small craft, but it was when I took the sprog to the Johnson Space Center that I saw with my own eyes just how enormous it was. They have one lying on its side outdoors, and it seemed to go on forever!

PS--We visited Johnson SC in 1995, when the son was around 8 years old. He *still* talks about how awesome it was. Anyone who hasn't been needs to add it to their bucket list.