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The Balloon Satellites of Project Echo

The world’s first communication satellite was remarkably unsophisticated—a big silvery plastic balloon coated with aluminum, soaring roughly 1,000 miles above the earth. It carried no active communication components, no relays. Just two FM transmitters for telemetry purposes, powered by nickel-cadmium batteries charged by solar cells. The satellite achieved its purpose by passively reflecting any radio signal directed towards its large shiny surface. For eight years it relayed radio and television signals, and made intercontinental telephone calls possible. The best part was—any individual with the right equipment could use the satellite at no cost.

Project Echo

Project Echo developed out of an idea by NACA (National Advisory Committee for Aeronautics) engineer William J. O’Sullivan, who, in 1956, proposed using an inflatable balloon to measure air drag in the upper atmosphere. The purpose of the experiment was to provide aerodynamic information crucial to the design of new aircraft, missiles, satellites and other spacecraft.

Although NACA agreed to the proposal, it told O’Sullivan to pack the satellite into a payload as tiny as possible because other experiments had almost completely taken up the space on the launching rocket. All that was left for O'Sullivan's inflatable balloon was a tiny space the size of a doughnut. Undeterred, O’Sullivan designed a balloon satellite only 20 inches in diameter when inflated, and weighing no more than seven-tenths of a pound.

Later, O’Sullivan was told to make the satellite 30 inches in diameter, otherwise it would be too small for the precision optical tracking cameras to see the satellite. However, O’Sullivan was warned that he couldn’t make the satellite take up more space in the rocket nor weigh a fraction more. Despite the bizarreness of the request, O’Sullivan was able to increase the size of the satellites by 10 inches without adding even a fraction of a gram to the weight. O’Sullivan would have liked to see the fruit of his work, but unfortunately, the rocket carrying the satellite malfunctioned and crashed into the Atlantic Ocean.

Even before the satellite’s fatal plunge into the ocean in April 1959, O'Sullivan had started to contemplate the benefits of a larger reflector satellite. Two years previously, O’Sullivan had proposed a 12-foot-diameter satellite that could be seen and photographed with the naked eye. In 1957, the Soviet had shocked the world by launching the world’s first artificial satellite, Sputnik, and government officials decided that a 12-foot inflatable sphere would be the right instrument of propaganda in the cold war. At that crucial moment, O’Sullivan delivered an impassioned speech before the Congress where he talked about a 10-story-high inflatable reflecting sphere that would allow radio frequencies not usable for long range transmission to be effortlessly reflected around the curvature of the earth, “thus creating vast new fields into which the communications and electronics industries could expand to the economic and sociological benefit of mankind.”

Project Echo

William J. O'Sullivan (right, standing) and an engineer examine the capsule containing the tightly folded and packed 12-foot-diameter Beacon satellite (left).

Before long, the small experimental program had ballooned into a full fledged satellite program called Project Echo. The size of the balloon satellite, informally called “satelloon”, also increased exponentially into a hundred foot.

The contract to build the satellite went to the Aeronautical Research Division of General Mills, the same company that manufactures breakfast cereals. But General Mills’ balloons were found to be faulty, and the plastic inventor Gilmore Schjeldahl, who made the first airsickness bag, was roped in. Schjeldahl helped solve many of the balloon’s defects including keeping the seams sealed, but his engineers still couldn’t figure out how to fold the  damn thing. The balloon not only had to fit inside a spherical canister, but it also had to unfold properly for inflation.

Project Echo

A technician inspects the container for Echo 1. On the right is the container partially separated to show the tightly packed satellite inside. Photo: Smithsonian museum

“Folding the beautiful balloon into its small container for packing into the nose cone of a Thor-Delta rocket was somewhat like folding a large Rembrandt canvas into a tiny square and taking it home from an art sale in one's wallet,” wrote Dr. James Hansen in his book Space Revolution.

As things were, Schjeldahl’s technicians were having a terrible time squeezing the balloon into a small room, let alone its intended canister. But a “eureka moment” by Langley engineer Ed Kilgore, after watching his wife fold a small plastic rain bonnet, helped solve the problem.

At Langley, Kilgore gave the hat to Austin McHatton, a talented technician in the East Model Shop, who had full-size models of its fold patterns constructed. Kilgore remembers that a "remarkable improvement in folding resulted." The Project Echo Task Group got workmen to construct a makeshift "clean" room from two by-four wood frames covered with plastic sheeting. In this room, which was 150 feet long and located in the large airplane hangar in the West Area, a small group of Langley technicians practiced folding the balloons for hundreds of hours until they discovered just the right sequence of steps by which to neatly fold and pack the balloon. For the big Echo balloons, this method was proof-tested in the Langley 60-foot vacuum tank as well as in the Shotput flights.

Success still eluded the team. The first launch of Echo on October 28, 1959, was a disaster. The launch and deployment were successful, but during inflation the balloon exploded, probably due to residual air left in the balloon. When the balloon was tested on ground, it needed 18 tons of air to inflate it completely. But in orbit, just a few pounds of gas was enough to keep it inflated. Even a tiny amount of extra air inside the balloon could expand into an enormous volume in the extremely low pressure of the upper atmosphere. The balloon exploded creating a spectacular 10-minute light show as thousands of fragments of the aluminum-covered balloon reflected the light of the setting sun.

Finally on 12 August 1960, a Thor-Delta rocket blasted into the sky from Cape Canaveral, taking Echo 1 into space. Once in orbit, the balloon was inflated using an evaporating powder. Minutes later, Echo 1 relayed the first radio message from President Eisenhower:

This is President Eisenhower speaking. This is one more significant step in the United States' program of space research and exploration being carried forward for peaceful purposes. The satellite balloon, which has reflected these words, may be used freely by any nation for similar experiments in its own interest.

To communicate with the Echo satelloon, Bell Labs built a 50-foot long horn-shaped antenna in Holmdel. Later, in 1964, using this same antenna, Drs. Arno Penzias and Robert Wilson detected the microwave background radiation, the first concrete evidence of the Big Bang theory. They were awarded the Nobel Prize for their discovery in 1978.

Project Echo

The Holmdel Horn Antenna in Holmdel Township, New Jersey, United States. Photo: Jeff Keyzer/Flickr

In 1964, Echo 2 was launched. The latest model was 135 feet across, but unlike Echo 1, Echo 2 had a fairly rigid body allowing it to stay in shape without a constant internal pressure. Because it was conspicuously larger, Echo 2 was visible to the unaided eye over all of the Earth. Echo 1 re-entered the atmosphere and burned up in 1968. Echo 2 followed the next year.

NASA launched another satelloon, called PAGEOS, in 1964. The 100-foot-satellite was meant for triangulation, and it did a great job at that, mapping the features on the earth’s surface with an accuracy of 3 to 5 meters, which was twenty times better than terrestrial triangulations at that time.

Project Echo

Test inflation of a PAGEOS satellite in a blimp hangar at Weeksville, North Carolina. Photo: NASA

In many ways, the Echo project changed prevailing conceptions of the potential for satellite communication systems. Initially, private telecommunications companies were not interested in satellites because they were already heavily invested in the ground network and because engineers thought that the earth’s ionosphere would weaken the intensity of the signals. The success of the Echo program encouraged private sector initiatives in this field. Eventually, balloon satellites fell out of favor to make way for satellites that actively transmitted signals.

References:
# Dr. James Hansen, Space Revolution, https://history.nasa.gov/SP-4308/ch6.htm
# Project Echo, https://crgis.ndc.nasa.gov/historic/Project_Echo
# Greg, The Satelloons Of Project Echo: Must. Find. Satelloons, https://greg.org/archive/2007/10/07/the-satelloons-of-project-echo-must-find-satelloons.html

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