The first of a pair of research satellite reflectors—LAGEOS, from Laser Geometric Environmental Observation Survey, was launched on this day in 1976 (the partner mission was launched in 1992) placing the aluminium covered brass sphere, dimpled and looking like an oversized golf ball, in an extremely stable orbit. The enduring experiment is designed to aid with satellite orientation and terrestrial distances with the highest precision available, due to their regular circumnavigation of the Earth.
