Decided to post this as a bug, as placing Atmosphere Harvesters on an Exotic planet is possible. I assume it should say ‘Invalid Biome’ instead, not allowing you to place them at all. It does allow you to place up to 3 max, harvesting ‘Big Ball’, consuming either Carbon or Condensed Carbon as usual. 
Basically bugged, not getting anything of course. I doubt anyone will actually try, but it should be fixed to be impossible. The icon shown, named as Big Ball, may be different for others …
