Metaphors for Outer Space

We are dealing with science fiction when writing about a space going merchant marine. There is of yet no space version of the merchant marine, so metaphors are useful for determining how you want things to work.

I see three primary metaphors.  First is Space is an Ocean. Second Space is Air. Third is space if boring.

Space is an Ocean
Much science fiction is written about space navies where the basic metaphor and setup for star going craft is model along navy lines as if space if an ocean.  For the merchant marine this space is an ocean  works fine if the technology supports it.  The way I see it, ships will have the look and feel of ships rather than aircraft if the voyage between planets, space stations, etc is long and requires consistent vigilance. You have to have at least one person ready to maneuver the ship at all times for the at least weeks long voyages. You see this in the Honorverse with trips in the few weeks to a few months; Chandler's John Grimes series with similar length trips; and Nathan Lowell's trip of 20 to 60 plus days.

You will have enough crew to stand a watch of 8 to 12 hours a day for weeks on end. You'll have enough other people, especially if you have passengers, to provide services like cooking and cleaning for them for weeks on end. Since this is commercial venture, the crew will be as small as possible unlike the Navy.

Space is Air
There is some science fiction where the metaphor is more like space if like air. In this case the model I see is commercial airlines.  The part of the voyage that needs a person at the controls is relatively short - probably under 12 hours. A good example of this is from Star Wars. In the original movie Hans Solo spends a short period of time getting the Millennium Falcon off the planet and into hyperspace.  Once in hyperspace there is nothing to do so him and Chewbacca can leave the cockpit and do what they want. Even a large ship might only a crew of 2 or 3 to control it, plus flight attendants to serve any passengers.

Space is Boring
In this scenario there are long periods of travel with nothing to do. The movie Alien is like this, where everybody is in suspension. Other ones might be 2001: A Space Odyssey where it's months of travel with only occasional checks and even rarer adjustments to the course.