http://mars.jpl.nasa.gov/msl/multimedia/images/

Now that you mention it, I remember Charles Stross writing about almost exactly this kind of solution. (Maybe in Saturn’s Children? Or perhaps I’m thinking of another story by a different writer?) In the story as I recall it, there’s a whole city that rides on an enormous set of rails that encircle the planet.

(Presumably the rails are made of some material that doesn’t melt in the extraordinary heat!)

The whole city is like a slow-moving train car, keeping just ahead of the Sun, “riding the twilight,” as you put it.

No idea what, if any, backup plans they had, in the event that the city couldn’t keep pace with the edge of night. An hermetically (pun not intended, but having noticed it, I’m keeping it) sealed megastructure like that could quickly turn into the solar system’s largest pressure-cooker.

(Given the vast difference in day/night temperatures, I suppose that’s kind of a “Janus”-like situation, even if there’s no “January” there?)

Visiting Mercury would be fun, as a scientist, or at least as a heavy-duty science robot. Returning from Mercury would pose a serious problem, though, as it would take enormous acceleration to escape the gravity of the Sun that far down the gravity well.

Beaming in temporarily via telepresence–or, to avoid communication lag, just downloading your mind, or a copy of your mind, or a part of your mind, etc.–to a high-functioning robot already on the planet, might be the best way to experience Mercury firsthand, while completely avoiding those crazy high fees for carry-on luggage.

Of course, if that historian from the earlier article is right, nobody will be making the trip until well after 2020. We’ll have to depend on the robots built by those asteroid miners at Planetary Resources. If those visionary billionaires just keep their nerve up during the coming troubles, they will have the assets in space to go to Mars.