A robotic rocket that can repeatedly take off and land vertically would have endless uses: As a lunar lander that can park itself at a fuel station, gas up, and immediately relaunch to ferry supplies elsewhere on the moon. Or as a space-tourism craft that can touch down safely on helicopter-like landing pads. That's why four years ago, NASA opened the $1-million Northrop Grumman Lunar Lander Challenge, a competition designed to encourage private companies to develop low-cost rockets with the precision, power and quick turnaround needed for moon and other missions. Last fall, an underdog team of six engineers at Masten Space Systems took home the prize. Their Xoie lander, assembled from commercial materials and parts, flew 50 feet above the Mojave Desert, navigated to a rocky target 50 yards away, and landed seven inches from its goal, beating rivals by two feet. Although Xoie (pronounced "Zoey") might not actually fly on the moon, its design could influence future crafts that do. It also proved that you don't need exotic, budget-busting technology to make a sophisticated spaceship. Here, Xoie's $300,000 worth of parts explained.