The anniversary of the launch was last week, but we'd be remiss if we didn't take a moment to commemorate the passing of 50 years since the U.S. sent aloft its first communications satellite. After all, this one shiny balloon opened the way to the vast array of much more advanced satellites that help enable so much of modern life.
The August 12, 1960, launch of the Echo 1A was the first successful one for NASA in its communications satellite program, almost three years after the launch of Russia's Sputnik and two and a half years after the U.S. put its very first satellite, the Explorer 1, into orbit. Not long thereafter, according to the space agency, Echo allowed President Eisenhower to make the first voice communication via satellite.
This image shows the original Echo 1 balloon being inflated in 1958; its launch attempt in May 1960 was not successful. The Echo 1A now is commonly referred to as Echo 1.
This image, with the car in the foreground, gives a better sense of the scale of the Echo balloon, which was 100 feet in diameter. The Mylar surface of the balloon reflected signals from Earth, making it a passive communications satellite--or "satelloon," as it was sometimes known at NASA. It handled radio, television, and telephone signals, including the first coast-to-coast phone call via satellite.
The Mylar polyester film was just 0.5 mil (0.0127 mm) thick. With its highly reflective surface, the Echo 1 was said to be easy to spot from the ground with the naked eye.
This is a 12-foot scale model of Echo being subjected to a "skin stress test" in May 1960. The prototype was that size, NASA says, because that's what would fit in the model shop at the agency's Langley, Va., facility.
NASA offers this additional technical information about Echo:
"It had 107.9-MHz beacon transmitters for telemetry purposes. These transmitters were powered by five nickel-cadmium batteries that were charged by 70 solar cells mounted on the balloon. Because of the large area-to-mass ratio of the spacecraft, data for the calculation of atmospheric density and solar pressure could be acquired."
Radio signals that bounced off the Echo 1 were received here, among other places, in this 50-foot-long horn reflector antenna at a Bell Telephone Laboratories facility in Holmdel, N.J. (The other end of the line was a NASA facility in Goldstone, Calif.) Built in 1959 for the Echo program and seen here in June 1962, the horn antenna later served as a receiver for broadcast signals from the Telstar satellite.
Echo 1 went out of service when its orbit deteriorated and it re-entered the atmosphere in May 1968. A second balloon, the somewhat larger Echo 2, was in service from January 1964 to June 1969.
In 1964, when this photo was taken, it wasn't just machines from IBM that were known as computers. So, too, were some NASA mathematicians who tracked the Echo satellites, including Melba Roy, seen here. (The terse title in the NASA photo archives says "female computer.")
To get into space, the Echo balloon was folded and placed in a canister, which was then loaded into a rocket. This Shotput launch vehicle was used for testing the ejection and inflation techniques, but the actual launch was done on a larger Thor-Delta rocket.
NASA says that one of the biggest technical challenges connected to Echo 1 was to design the container that had to carry the balloon into space, then open up properly to allow the balloon to inflate. The effort included the construction of a special-purpose vacuum chamber for testing. "The container-opening mechanism that eventually resulted from these vacuum tests was surely one of the oddest explosive devices ever contrived," wrote James R. Hansen in "Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo."
The canister containing the Echo balloon opened into two hemispheres when an explosive charge was detonated in the ring between the hemispheres. The system, NASA says, was laced together with fishing line.
Although NASA's work with passive satellites in the Echo program gave way to projects involving active technology, the space agency isn't done working with balloons. For a look at more contemporary efforts involving balloons, see "Wallops Flight Facility, NASA's hidden launch shop."