Exosphere: Others knew it too. Teresa's sharp eyes picked out sparkling glints which were aircraft - jets and the more common, whalelike zeppelins.
Lithosphere: "If we hurry we can make it to Drop Point by eight and catch the last zep into Butte"
Lighter than air transport has the following points in favour in a society that is increasingly conscious of its impact on the environment:
It has one large drawback; the lack of a convenient source of buoyancy:
70 years after the Hindenberg disaster, lighter than air transport is poised to make a comeback. Whether it becomes the transport of choice for medium-long haul journeys is moot.
A little speculation of mine own:
with hydrogen too dangerous, and helium too expensive, what else could be used to provide bouyancy?
(The answer is, of course, nothing at all!;-)