Thanks a lot, guys! I really wonder why I didn't get tired of that..
There is a plant here and there, but they are mostly too small to show.
Since the two models (NASA and Kuhn) show different stages of the configuration, I took some parts of the NASA model and sticked it onto the Kuhn model. I don't know, if this is correct, but I thought it looks cool.
The RTP should show any plants and other geometry that the full render does. If you can't use the RTP or don't want to, you probably just need to adjust the clipping distance of your 3D preview. Use the [ key a few times...