Blast From The Past: Project Echo Still Echoing

Post by AJ Rise:

Here’s a little bit of neat space technology history: Project Echo was one of the earliest experiments in satellite communication, launched in the 1960s, and it paved the way for communicating satellites, which remain essential to our everyday lives.

Echo 1 was the very first passive communications satellite to be launched into space and relay signals back to Earth. In contrast to an actively communicating satellites, Echo merely reflected signals from Earth back down to the planet’s surface. The first message was sent from Jet Propulsion Laboratory in Pasadena California, reflected off Echo, and received at Bell Labs on August 12, 1960.

When Echo was first inflated, the incredibly thin balloon layer failed, breaking apart the shell into thousands of sparkles suspended in the air. Unaware that this was unintentional, the media applauded NASA for a very scientific and beautiful light show.

Echo
Echo 1 shell undergoing stress testing on May 1, 1960. The testing conditions, 2000 PSI at 87 degrees Fahrenheit, are visible on the paper attached to the side. (Credit: NASA, images of the day).

The first attempt to launch Echo into orbit occurred in May 13th, 1960. A misfiring engine on the Thor-Delta rocket sent the satellite into the Atlantic Ocean. Although bright, this was never applauded as a light show. A later launch of the same rocket successfully put the satellite Echo 1A into low earth orbit.

The satellite took the form of a balloon entirely coated in mylar. This 30-micron layer was able to reflect television, radio, and microwave signals back to earth – the technology’s defining feature. When launched, it weighed a total of 157 pounds. It was inflated upon its arrival in orbit by means of a sublimating powder to a diameter of 30.5 meters (100 ft). Some excess powder was kept within the balloon to compensate for skin permeability and meteorite punctures. Large and reflective, Echo 1 was visible on the surface as a small, shiny spectacle moving across the sky. It remained a lot much longer than its expected shelf life, burning up in the atmosphere in May 1968.

Echo 1 helped develop our understanding of the solar sail effect, the wrong way. Its reflectiveness and low mass meant that photons from the sun actually altered its telemetry. This misshapen discovery remains a fundamental principle of our ability to efficiently send nanotechnology into deep space.

Project Echo launched a second balloon, Echo 2, on January 25th, 1964. This satellite was slightly larger (135 feet) and included basic instrumentation which aided in the development of modern satellite tracking. Unlike Echo 1, it’s skin was rigidizable, and lacked the need for a constant re-supply of gas. Once inflated, it maintained its shape without conscripting additional internal pressure.

Echo 2
Echo 2’s fully rigidizable shell, fully inflated in Weeksville, NC in 1964. Echo 2 was a whopping 135 feet in diameter. (Credit: Great Images in NASA)

On-board instrumentation on Echo 2 measured its internal temperature and pressure and reported the satellite’s position to NASA. These technologies are critical for the function of modern satellites.

The Echo program furthered our understanding of passive and active satellite communication, orbital mechanics, satellite telemetry, radiation, and more. These concepts remain vital for several technologies we use today. Cellular networks, GPS, television broadcasts, and the extent of the internet would not be possible without the ability to design, launch, and communicate with satellites.

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