Technician Floating Up and Down to Inspect Echo II, a NASA Satellite, 1963

A technician conducting a manual inspection of the Echo II communications satellite during a test inflation in 1963. The massive, highly reflective Mylar balloon, which served as a passive communications relay by reflecting radio signals back to Earth, was inflated inside a hangar at Lakehurst, New Jersey. To check for leaks and flaws across the surface of the gigantic, 135-foot-diameter sphere, the technician used a small personal balloon tethered to the ground to float up and down alongside it. This unusual and striking method of inspection resulted in the dramatic photo you see.

The Echo satellite program was NASA’s groundbreaking experiment that pioneered the use of space for communications by using large, passive reflective balloons.

The Echo satellites were essentially enormous, aluminized Mylar balloons that did not carry electronic instruments for receiving or retransmitting signals. Instead, ground stations on Earth beamed microwave signals at the satellite, which simply bounced the signals off its highly reflective surface to other ground stations across long distances.

The primary goal was to test the feasibility of satellite communications and other new space technologies. Experiments conducted during the program helped measure atmospheric drag, evaluate temperature control in orbit, and test satellite tracking methods.

Echo 1, launched on August 12, 1960, was 100 feet (30 meters) in diameter. It successfully relayed the first transcontinental voice circuit, including a prerecorded message from President Dwight Eisenhower. It remained in orbit for nearly eight years, visible to the naked eye as a fast-moving “star.”

Echo 2, launched in 1964, was larger at 135 feet (41 meters) in diameter and had a more rigid design to maintain its shape better in orbit. It was used for scientific investigations and famously for the first space-based collaboration between the U.S. and the Soviet Union, reflecting a signal from England to Russia.

Although eventually superseded by more advanced active repeater satellites (which amplify signals), the Echo program provided the technological foundation for modern satellite communications. The distinctive horn antenna at Bell Labs used for the project later played a pivotal role in the Nobel Prize-winning discovery of cosmic microwave background radiation, a key piece of evidence for the Big Bang theory.