First spaceship to travel to Mars and encounter harmless aliens

Lester del Rey : Author
"Chuck Svenson, a seventeen-year-old living on the Moon, is chosen to be one of six crewmembers of the first spaceship to travel to Mars. His juvenile status keeps him from being allowed to take the position, once his age is discovered. He boards as a stowaway, and is accepted by the other crew upon discovery. The Mars landing is a disaster, damaging the ship. While attempting to repair the ship, the crew encounter aliens, who abduct Chuck without harming him"