5413 번 : Robintron 
 5413 번 
 5413 번 - Robintron 
 It is during the great war in the year 2240 that the Robinson family decides to leave the human empire , in search for more peaceful and quiet places . The Robinsons already have a planet in mind to which they wish to travel and want to get there as soon as possible . However , because all vehicles capable of spaceflight are being used for the war , the Robinson family has no way to escape to other planets by means of ordinary space flight . It is therefore that Joe Robinson , the father of the family , created the Robintron . The Robintron is a vehicle that is capable of travelling from one planet ' s surface to another by only using the forces of gravity . 
 It is the gravitational pull of a planet that keeps the Robintron on a planet ' s surface . This pull extends as far as the planet ' s gravity well , a circular area around the center of the planet , which is generated by the planet ' s mass . However , these gravity wells can also be used to assist the Robintron in leaving a planet by the way of planet hopping . Planet hopping can be performed when the Robintron is on the surface of a planet and comes within the area of another planet ' s gravity well . The Robintron uses the other planet ' s gravity well to gain enough momentum to escape into space , and to land on the other planet ' s surface . Leaving a planet and subsequently landing on another one takes no significant amount of time . 
 The Robintron ' s journey always starts at the first listed planet and its destination is always the last listed planet , which is always reachable from the Robintron ' s starting position . The star ( at position [ 0 , 0 ] ) is too hot for the Robintron and cannot be used for planet hopping .