Elon Musk’s SpaceX has been working on a system that will return the launch missile intact to its launch pad, ready for the next launch. This video clip was taken two days ago at their Texas launch facility. They moved the rocket horizontally 100 meters, hovered, and tilted it 30 degrees from vertical.
This is a step toward the goal of using Grasshopper to boost succeeding stages to a high altitude before it returns to its launch pad.
SpaceX CEO Elon Musk’s reasoning: This booster, while “cheap”, costs 50 to 60 million dollars. The fuel costs about two hundred thousand dollars. If we can re-use the booster a thousand times and amortize its capital cost over a thousand launches, the cost per launch will be low.
This is a triumph of servo system design and high-pressure high-flow rate fluid control. The trick is to make the rocket’s engine respond quickly while keeping the servo loop stable. I imagine that the signals from many sensors of all types are monitored by the guidance computer. The resultant control of thrust is impressive.