Among its diverse and expansive exhibits , the Museum features a full-size replica coal mine , a German submarine ( U-505 ) captured during World War II , a 3,500-square-foot ( 330 m2 ) model railroad , the first diesel-powered streamlined stainless-steel passenger train ( Pioneer Zephyr ) , and the Apollo 8 spacecraft that carried the first humans to orbit the Moon .
It has a full-size replica coal mine , a German submarine ( U-505 ) captured during World War II , a 3,500-square-foot ( 330 m2 ) model railroad , the first diesel-powered streamlined stainless-steel passenger train ( Pioneer Zephyr ) , and the Apollo 8 spacecraft that carried the first humans to the Moon .