Destination Moon ending explained (spoilers)

[Mai Lan]

The entire crew of rocketship Luna make it back to Earth by their wits and the skin of their teeth, even though earlier they were drawing straws to determine who'd have to stay behind due to a severe propellant shortage.

[beth]

Lunar Industries has been using clones of Sam Bell for the past 12 years. The clones life-spans only last the duration of their 3-year contract. Instead of being shipped home they unknowingly incinerate themselves. The Sam Bell from the start of the movie is at the end of his life-span and helps his replacement to escape. Before he leaves, the replacement destroys the jammer which prevented live feeds to the base. The replacement escapes to Earth and brings this to the attention of the media.