This page describes some common knowledge about space travel. Spacers must all know and understand these things. Passengers on the Zheng He might not know it as well, but many are probably familiar with these basic facts too, either from explicit training or prior space experience, or having picked it up from the crew.
The Modern Spaceship
Spaceships come in lots of varieties - there's as many kinds of spaceship as there are airplanes or boats. They can be categorized in several ways.
Atmospheric ("shuttles") spacecraft: Most big ships are built in space and would be destroyed if they tried to land on a planet, by some combination of the heat of atmospheric entry or the forces experienced during it. Atmospheric shuttles turn the atmosphere to their advantage by having wings - basically, they're a combination spaceship / airplane. (The NASA space shuttle is a familiar real-life example, though modern shuttles are single-stage-to-orbit craft more like the proposed REL Skylon.)
Landers: The atmospheric spacecraft's counterpart for landing on planets with no significant atmosphere. Big ships often lack the acceleration to make a soft landing even on fairly low-gravity worlds, so these specialized craft with appropriate high-acceleration engines are used to land on, and take off from, airless bodies. They may also double as orbital tugboats or space-to-space shuttles, though their efficiency is lower than purpose-built craft.
Orbital Craft: Orbital craft move about generally within a planetary system, and may also be atmospheric spacecraft or landers. They are usually fairly small. They accelerate and manoeuvre well, being very good for rendezvous, docking, and supporting activities. Usually, they do not have comfortable long term accommodations for their crew and conduct short missions of a few days maximum. They are often based at space stations where the crew live. Many orbital craft have no crew and are actually drones, controlled by crew in a control room on a planet or station. If they break down in orbit, another vehicle is usually available to rescue them, so reliability, while still important, is not their dominating design consideration - self-sufficient maintenance is not expected.
Interplanetary Ships: The backbone of space commerce. As important as interstellar commerce is, most cargo and passengers that go to space do so to travel to another planet, space station, or moon in the same star system. Economical interplanetary shipping relies heavily on economies of scale, so that large, efficient engines can be used. Some interplanetary ships are uncrewed and use highly efficient, low-acceleration engines, taking years to get between planets. They are maintained by teleoperated onboard drones. (This approach is not as effective as having humans onboard or at least nearby, where they can operate the drones efficiently without long speed-of-light delays, but it is very cheap.)
Laws concerning the rights and training of interplanetary ship crews are not determined by the Allied Worlds in most systems, but by system-level or lower organizations. In most cases, they are less favorable to the personnel than the equivalent AW policies either for the Allied Worlds Space Force or for interstellar merchant vessels. An area of current controversy is hibernation pay. Interstellar ships, regulated by the AW, are required to pay crew at least 75% of their normal pay for time spent in hibernation, and the Space Force pays 100% as an inducement. However, this regulation does not apply to interplanetary ships that do not use the wormhole gate system.
Interstellar Ships: Interstellar ships are those able to go through wormholes.