A "Sky Hook" is a theoretical concept in space engineering that refers to a device designed to capture objects in orbit without the need for rockets. It typically consists of a long cable or tether that extends from a satellite or space station, allowing it to snag passing spacecraft or debris. This method could potentially reduce the cost and complexity of space missions. The idea of a Sky Hook is often associated with the work of physicist Robert L. Forward, who proposed using such a system for space transportation. By utilizing the Earth's rotation and gravitational forces, a Sky Hook could facilitate the transfer of materials and spacecraft between different orbits efficiently.