Previous Grasshopper tests relied on the other rocket sensors but for this test, an additional, higher accuracy sensor was in the control loop. In other words, SpaceX was directly controlling the vehicle based on new sensor readings, adding a new level of accuracy in sensing the distance between Grasshopper and the ground, enabling a more precise landing.
Grasshopper is a 10-story Vertical Takeoff Vertical Landing (VTVL) vehicle designed to test the technologies needed to return a rocket back to Earth intact. While most rockets are designed to burn up on atmosphere reentry, SpaceX rockets are being designed not only to withstand reentry, but also to return to the launch pad for a vertical landing. The Grasshopper VTVL vehicle represents a critical step towards this goal.
Grasshopper consists of a Falcon 9 rocket first stage tank, Merlin 1D engine, four steel and aluminum landing legs with hydraulic dampers, and a steel support structure.
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