space shuttle vs train ferry

space shuttle

noun
  • Any vehicle capable of repeatedly travelling between destinations in outer space carrying people or cargo. 

  • Any vehicle capable of travelling repeatedly between the Earth's surface and outer space carrying people or cargo. 

train ferry

noun
  • A ferry used to transport rail vehicles from one railway line to another across a stretch of water. 

How often have the words space shuttle and train ferry occurred in a corpus of books? (source: Google Ngram Viewer )