In my current writing project, I'm working in a universe where mysterious alien beings travel not directly through space, but through planetary atmospheres via wormholes. These aliens shotgunned through our Solar System, networking our planets together among themselves and among other exoplanets around other star systems, and beyond.
These connections not only facilitate the aliens' travel through space, but ours as well. The wormholes function as the backbone of an interstellar economy and human civilization.
Spacecraft traveling along routes through the wormholes will need to re-enter atmospheres frequently. Consider this: a spacecraft re-enters and traverses a wormhole, exiting in the atmosphere of the other planet. The spacecraft queries a satellite network, which relays the position of the next wormhole along the spacecraft's intended route. The spacecraft then boosts back into orbital or suborbital flight, depending on where that next wormhole lies. (It may also boost into orbit to refuel or make repairs.)
(Suborbital flights would obviously be preferable for lower energy cost; however, depending on distance to the next wormhole and the spacecraft's time profile, exiting the atmosphere and assuming orbit might be preferred. In addition, the wormholes themselves migrate through the atmospheres, oscillating between higher and lower [dense & less dense] altitudes. While one side of a wormhole may be in the upper atmosphere, the other may be hundreds of kilometers deep in a jovian counterpart, unfit for entry or exit.)
Essentially, (suffice it to say) it is economically favorable in my universe for spacecraft to be timely and make re-entries at high frequencies. My question is: what re-entry technologies would likely be employed by my civilization with these rapid-repeat re-entries in mind? In essence, I'm asking for an extrapolation of a most efficient (durable) spacecraft design for this task.
Constraints: wormhole entry windows are on average open for 5-6 hours per 24 hours (so, a re-entry method shouldn't take much longer than this); it is also economically favorable for spacecraft to be "lightweight" (say, less than 800 tons, the majority of which isn't shielding, etc.1). A spacecraft should need little repairs; for example, if a solution is some kind of ablative shielding, it should hypothetically withstand longer than its competitors.
Conditions: assume the average spacecraft cycles through re-entry, orbital boost-back, re-entry, etc. (occasionally stopping in a parking orbit for fuel, less so for repairs), and assume for simplicity that the atmospheric conditions around each wormhole are Earthlike at sea level. (It'll be simpler to work with what we presently know regarding re-entry vehicles on Earth, however, I may in the future ask a similar question for re-entries in other atmospheres.)
1 While a spacecraft comprised mostly of heat shielding would almost certainly require little in the way of repair, companies are in the business of transporting cargo and people, not heat shielding.
Clarification: it is human civilization using these wormholes. I am asking about how we may develop spacecraft to handle these stresses.
For additional information about this specific worldbuilding, see this question.