pics

PAGEOS had a diameter of exactly 100 feet (30.48 m), consisted of a 0.5 mils (12.7 μm) thick mylar plastic film coated with vapour deposited aluminum enclosing a volume of about 524,000 cubic feet (14,800 m3)[8][9] The metal coating both reflected sunlight and protected the satellite from damaging ultraviolet waves. The satellite was launched in a canister, which explosively separated as it was ejected from the rocket. Then, the balloon was inflated through a combination of residual internal air and a mixture of benzoic acid and anthraquinone placed inside, which turned to gas when the satellite was exposed to the heat of the sun.[9] It was the first satellite specifically launched for use in geodetic surveying,[3] or measuring the shape of the earth, by serving as a reflective and photographic tracking target. At the time, it improved on terrestrial triangulations of the globe by about an order of magnitude.[4] The satellite, which carried no instrumentation, broke up between 1975 and 1976.

Wikipedia

This was super interesting to read about. I thought the picture surely had to be CG or AI created at first.