Let me be the first to say that it's a space station
A) high albedo--indicating reflective surface
B) But reflective surface is not ice
C) It must therefore be metal!!!!!
Obviously, it's a space fortress intended to keep us primate inmates in our place!!!
Alternatively, Lilo and Stitch was right, and we are some kind of galactic nature preserve, and the space fortress is to keep the poachers out!