One thing that just about all interstellar civilizations need if they want to be anything more than long-distance friends is a way to get from their starships down to the surface of planets and back up again. In other words, they need some flavor of shuttlecraft that can survive re-entry into a planetary atmosphere and then reach orbit again without the need for extensive ground support, as they may have to land on Earth today and Mars in a few days.
This craft must be able to:
- Re-enter and land on the surface of rocky, not-too-hot planets (Earth works, Mars works, Venus or Mercury can be excluded though. Bonus points if you can get onto larger versions of Earth or Mars.)
- Take back off again without the need for dedicated launch support facilities (a clearing, road, or ordinary runway should suffice -- can't have a strongback/TEU or ground refurb facility in this application)
- Reach orbit without shedding large parts (leaving trash in other people's planetary space is rude, don't you think?)
- Maneuver on-orbit in an agile fashion (i.e. not limited to preset orbital parameters or automatic guidance)
- Operate without replenishment of consumables or refurbishment of the craft for 1 Earth week, minimum, including fuel/oxidizer/reaction mass and life-support consumables
- Provide for an operating crew as well as roughly a dozen passengers and their supplies or two tons of cargo, at a minimum (more is better)
The builders have:
- Ample supplies of materials that can withstand re-entry temperatures on Earthlike planets multiple times without refurbishment (or the worst case target planet if other than Earthlike)
- The ability to develop engines capable of equal or greater specific impulse and delta-V to the state of the art in current rocketry (nuclear-thermal and fusion-thermal are both explicitly on the table, but if they can do better, they will)
- A knowledge of structures, aerodynamics, and chemistry at least equal to ours, but still bounded by physical limits
- The ability to use the main engines to generate ample electric power (not hard)
The builders are also land-dwellers with the ability to dexterously manipulate fine controls and are on a human-scale (provided the life-support is compatible, a human could ride in, or even be trained to operate, this craft).
What design of craft would pop out of this?