The Rock Raiders are a LEGOLAND off-planet mining/exploration corporation that was created in 1999 to map out the Milky Way Galaxy. However, their ship, the LMS Explorer, was heavily damaged by asteroids on the way back and was pulled into a wormhole that led them to a barren solar system on the Outer Rim of the Leg-Godt Galaxy.
After landing on Planet U, the Rock Raiders discovered an abundance of crystals that could power their crippled ship. After facing unstable caverns and deadly aliens, the LMS Explorer regained power and returned to Earth, where they were sent back to the solar system a few years later to mine more crystals for the LEGOLAND government, who saw the crystals as an enviromentally-friendly power source.
However, the Rock Raiders' purpose basically became nullified as another government-issued mining organization, the Power Miners, discovered Energy Crystals on Earth as well.