In the near-to-mid future when ISRU and manufacturing in space is large enough to have an export industry back to Earth, there may be not only a significant volume of raw materials heading back to earth, but also a sizeable quantity of delicate finished goods (e.g. electronics).
While getting things back down may be orders of magnitude easier than bringing them up, doing it on scale poses its own problems. For small quantities of goods, I can imagine them easily being brought back down on a Starship. But once Tonnage to Earth exceeds Tonnage to Space, you have to come up with a different way of getting things down.
There are several challenges:
- The craft must survive re-entry
- The craft needs a mechanism to slow down
- The craft must be steerable to a certain designated crash point on Earth's surface.
- This crash point needs to be a decent distance away from people or animals.
- The craft needs to decelerate at a rate low enough to ensure the survival of the cargo.
- The craft needs to be as light as possible, because it is either being transported up from Earth or it is being manufactured in space, meaning the raw materials are at least a handful of km/s of delta-V away.
For the transport of raw materials like metals, some of these requirements may be less stringent. The craft containing raw iron could come in quite fast, providing the end collision isn't at such a high velocity as to scatter the material everywhere. For such purposes, a craft would obviously be single use.
For more delicate imports that have a maximum G-force a human would relate to, its landing craft would probably be partly reusable. with engines and parachutes manufactured and refurbished on earth and sent up into space in bulk, and a single use ablative carbon frame manufactured in space.
Have there been any proposals or other work done on this front? How do you transport goods down to Earth's surface at a scale larger than your ability to get tonnage to orbit?