rocket scientist          
noun [ C ] uk/ˈrɒk.ɪt ˌsaɪ.ən.tɪst/ us/ˈrɑː.kɪt ˌsaɪ.ən.tɪst/
 火箭科学家,火箭学家
someone who studies rockets
  a retired rocket scientist 退休的火箭学家 
  聪明人
If you say that someone is not a rocket scientist, you mean that they are not very intelligent.
  He's not exactly a rocket scientist. 他并不是那么聪明。 
 See: rocket science
 - More examples
 - I don't think it takes a rocket scientist to figure out what you ought to do next.
 - He spent about five years as a rocket scientist at NASA's Jet Propulsion Laboratory.
 - A pioneer rocket scientist whose career spanned five decades, Hunter joined Douglas Aircraft in 1944.
 - "None of them are rocket scientists," said Johnson, noting that many of DiNunzio's predecessors were convicted, partly based on recordings of them saying foolish and incriminating things.
 - They're not exactly rocket scientists.