Imagine the year is 2170. You and a huge international team of engineers are cha
ID: 112220 • Letter: I
Question
Imagine the year is 2170. You and a huge international team of engineers are charged with the first ever stellar-scale building project, inspired by the 1970 Science Fiction Novel by Larry Niven, Ringworld. Your task is to design and build a ring-shaped ribbon surrounding the entire sun that will become home to billions of humans as well as plants, crops, pets, and livestock. The width of this ribbon is to be 6000km (comparable to the radius of the earth), with the side facing the Sun being built perfectly perpendicular to the direction of its radiant flux so that incoming sunglight can be used for producing electricity, growing crops, and naturally lighting homes and businesses 24hrs a day, 365 days an Earth year. At what distance from the Sun would you need to build this ribbon so that it receives a comparable level of solar radiation to the equatorial regions of Earth at the Equinox?
Explanation / Answer
The idea is good but it is very problematic even in my imagination.
Apparently, its look like we should build this ribbon at a distance similar to the equinox at the Earth. As we have the same radius or width of the ribbon as the earth(about 149.6 million km). But the problem is that our (imagined) ribbon will not get the atmospheric protection. Remember our atmosphere reflected more than 30% of the solar radiation back to space. But, as our ribbon does not have this atmosphere it will be way hotter than the earth at its equinox. And if we talk about the 6000km width of the earth compare to this ribbon, the earth has lots of hard material within it. That material has different heat conductivity. This material has always conduct lots of heat comes from the sun. So the material made of the ribbon also a point of concern. Another thing, the earth not only get its heat from solar radiation but it also has its own emission of energy as heat. So that must be another point of concern. So, overall the distance from the sun to the ribbon should be more than 149.6 million km.But if we imagine an earth with no atmosphere, solar radiation is the only source its heat energy and material of the ribbon has the same heat capacity compared to the overall heat capacity of earth material then the distance should be 149.6 million km. Still, I say 'should be' because there are a lot more things can be debated about.