What word that start with a means travel in spacecraft?
The word is astronaut. It means a person who is trained to travel in a spacecraft.
The noun spacecraft is a common noun, a word for any spacecraft of any kind. A proper noun is the name of a specific person, place, thing, or a title; for example: Kelly Johnson, American Systems and Aeronautical Engineer (spacecraft designer), team leader at Lockheed Martin "Skunkworks". Spacecraft Lane, Hauppauge, NY or Spacecraft Drive, Atwater, CA Spacecraft, Inc. (artists cooperative), Seattle, WA "How Spacecraft Fly: Spaceflight Without Formulae" by Graham Swinerd