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RE: [amsat-bb] Echo Balloons

On 3/2/1999 10:38 AM David R. Fordahm wrote:

Is anyone on this list old enough to remember a satellite called 
"Echo I"? ... Or "Echo II"?

I don't remember the dates of the Echo program, but it had to be 
back in the early 1960s.

Echo I and II were nothing more than *BIG* balloons.  I don't 
remember the details, but it seems like they were simply huge mylar 
(had mylar been invented yet?) silvery balloons with a miniscule 
amount of gas (a CO-2 cartridge or less) to keep them inflated in 
space.  They orbited for several years, and were about 200-feet in 
diameter (or something like that, as I said I don't remember the 
exact details).  They were *brilliant* ... first magnitude, or even 
minus-one or minus-two magnitude.  Their low orbits made them really 
zip across the sky.


Here's the results of a little research:

On 28 October 1959, NASA launched a prototype Echo ballon from 
Wallops Station, Wallops Island, Va.  A Sergeant-Delta rocket 
carried the ballon to an altitude of 250 miles.  The 100-foot 
diameter aluminum-coated Mylar-plastic sphere was used as a 
passive electronic reflector.  It was developed by NASA 
Langley's Space Vehicle Group under the direction of William J. 

The first Echo balloon was launched in 1960.

A Thor-Agena rocket placed the Echo 2 balloon into orbit on 
Jan. 25, 1964.  Echo 2 was a spherical balloon, 135 feet (41.1 
meters) in diameter.  It remained in orbit for two years and 
was used for many experiments.  The Agena was an upper-stage 
rocket developed for the Air Force by the Lockheed Propulsion 
Co. It used liquid propellants and had inflight shutdown and 
restart capabilities.

Bell Labs used a 20-foot horn reflector at Crawford Hill, 
Holmdel, NJ (now an historic site) for pioneering work in 
satellite communications.  It was used to detect radio waves 
bounced off Project Echo balloon satellites.  As an intersting 
aside, the antenna was also used for early Telstar satellite 
experiments.  To measure the faint radio waves from Telstar, 
they had to eliminate all recognizable interference from their 
receiver.  To remove the effects of radar and radio 
broadcasting and supress interference from the receiver itself, 
they cooled it with liquid helium to -269 C, only 4 above 
absolute zero (where all motion in atoms and molecules stops). 

A third Echo balloon test was launched on 27 February 1960, 
from NASA Wallops Station, VA.  The 100-foot-diameter 
inflatable sphere reached a suborbital altitude of 225 miles.  
Radio transmissions were reflected via the sphere from Holmdel, 
N.J., to Round Hill, MA.

Pete Greene, N2LVI
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