So, Sci fi in many forms of media loves some sort of drop ship that can come down from orbit, pick up some people, and fly off again back up to orbit - the characters on the ground don't need to any particular infrastructure in place to get picked up by a dropship: a clearing/LZ that would be suitable for a Helo pickup is just about it. Then there's the other way around, shuttles that can take people to orbit, and come right back down to some spartan(not in the Halo series sense) base.