This is an American science fiction movie about three astronauts who are on a mission to Mars. When they find a stowaway on board, the crew must figure out a solution, since they only have enough oxygen for three people. Vocabulary: space shuttle: a space vehicle stowaway: a person on board a ship who wasn't supposed to be there lifeguard: a person who works at a pool or beach to protect people from drowning oxygen: the element we use for breathing ethical or moral dilemma: a problem in which it's not clear what decision is right or wrong unconscious: not awake concussion: injury caused by being hit on the head