Protagonists Mario Esteban Rioz and Ted Long are Scavengers: Mars-born humans who scour space for the spent lower stages of spacecraft, which are then recycled on the Martian moon
Phobos. At the beginning of the story, Rioz scolds Long for wasting power listening to Grounder (Earth-born) politician John Hilder's argument that Earth's settlements on
Mars,
Venus, and the
Moon are useless drains on Earth's economy, and that spaceships are wasting irreplaceable water by using it as
reaction mass. A year later, Hilder has used his campaign against "Wasters" to gain power in Earth's Assembly, and has just reduced shipments of water to Mars, putting the Scavengers out of work. When Hamish Sankov, the head of the Martian colony, learns of Hilder's plan to terminate
all water shipments to Mars, he authorizes Long's plan to travel to
Saturn and tow a fragment of ice from the
rings to Mars. A fleet of 25 Scavenger ships makes the trip. Reaching the rings, the Scavengers choose a fragment approximately one cubic mile in volume, carve it into a rough cylinder, embed their spaceships in it, and fly it back to Mars, using the fragment's ice as reaction mass, in five weeks. On Mars, Hilder's allies are pressing Sankov to terminate all water exports to the Martian colony. When he hears from the returning Scavengers, Sankov signs. Two days later, the Scavengers land their ice-spacecraft in full view of the press, and Sankov announces that the fragment they brought holds 200 times the amount of water that Earth had been sending to Mars annually, and that if Earth cannot afford to lose any more water, the Martians will sell some of theirs. Long takes this situation as confirmation that Martians, instead of Terrestrials, shall colonize the remaining
Solar System. ==Influence==