NASA's Echo 1 satellite was built by
Gilmore Schjeldahl's G.T. Schjeldahl Company in
Northfield, Minnesota. The balloon satellite would function as a reflector, not a transceiver; after it was placed in a
low Earth orbit, a signal could be sent to it, reflected by its surface, and returned to Earth.
During ground inflation tests, 40,000
pounds (18,000
kg)
of air were needed to fill the balloon, but while in orbit, several
pounds of gas were all that was required to fill the sphere. At launch,
the balloon weighed 156.995 pounds (71.212 kg), including 33.34 pounds
(15.12 kg) of
sublimating powders of two types. According to NASA, "To keep the sphere inflated in spite of
meteorite punctures and skin permeability, a make-up gas system using evaporating liquid or crystals of a subliming solid were [
sic] incorporated inside the satellite." One of the powders weighed 10 pounds (4.5 kg), with a very high
vapor pressure; the other had a much lower vapor pressure.
The first attempt to orbit an Echo satellite (also the maiden voyage of the
Thor-Delta launch vehicle) miscarried when Echo 1 lifted off from
Cape Canaveral's
LC-17A on the morning of May 13, 1960. The
Thor stage performed properly, but during the coasting phase, the attitude control jets on the unproven
Delta stage failed to ignite, sending the payload into the Atlantic Ocean instead of into orbit.
Echo 1A (commonly referred to as
Echo 1) was successfully put into a orbit of 944 to 1,048 miles (1,519 to 1,687 km) by another Thor-Delta, and a microwave transmission from the
Jet Propulsion Laboratory in Pasadena, California, was relayed by the satellite to
Bell Laboratories in Holmdel, New Jersey, on August 12, 1960.
The 30.5-meter (100 ft) diameter balloon was made of 0.5-
mil-thick (12.7
μm)
biaxially oriented PET film, metalized at a thickness of 0.2 micrometers (0.00787 mils) (a type of film commonly known by the trade name
Mylar), and had a total mass of 180 kilograms (397 lb). It was used to redirect transcontinental and intercontinental
telephone,
radio, and
television signals.
It also had 107.9 MHz telemetry beacons, powered by five nickel-cadmium
batteries that were charged by 70 solar cells mounted on the balloon.
The spacecraft aided the calculation of atmospheric density and
solar pressure, due to its large area-to-mass ratio. During the latter portion of its life, it was used to evaluate the technical feasibility of
satellite triangulation.
As its shiny surface was also reflective in the range of visible
light, Echo 1A was easily visible to the unaided eye over most of the
Earth.
The spacecraft was nicknamed a "satelloon" by those involved in the project (a
portmanteau combining
satellite and
balloon).
It was originally expected that Echo 1A would not survive long
after its fourth dip into the atmosphere in July 1963, although
estimates allowed the possibility that it would continue to orbit until
1964 or beyond. It ended up surviving much longer than expected, and finally reentered Earth's atmosphere and burned up on May 24, 1968.
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