From the Winter 1960 Issue of the Collins Signal magazine.
ADVANCING COMMUNICATIONS RESEARCH THROUGH AN ECHO

During August NASA succeeded in orbiting the silver “sateloon,” as it was nicknamed, of Project Echo. The proper name of the satellite, of course, was Echo I. In Greek legend, “Echo” was a forest nymph. Having fallen in love with a handsome youth who ignored her, she pined away until nothing remained of her but a voice that was doomed forever to repeat only the words of others.

Micrometeorites and solar rays, rather than unrequited love, will eventually cause the fading away of Echo I. But during its comparatively short life, it will have provided scientists and engineers with valuable data on the peaceful (and potentially commercial) aspects of space research.

This most spectacular of artificial satellites in orbit is a 100-foot sphere of aluminized Mylar plastic. Orbiting the earth at distances exceeding 1,000 miles, Echo I shines brighter in the night skies than the North Star. Although at this writing, the globe launched on August 12 has lost much of its original roundness - flattened on one side by solar heat and innumerable perforations from encounters with particles of spatial dust - like its legendary prototype, Echo I continues repeating the sounds it “hears” from other sources.


Echo satellite test inflation. —NASA photo
Project Echo, of which Echo I represents the first successful step, is an experimental program conducted by the National Aeronautics and Space Admin-istration with a threefold purpose: testing the feasibility of orbiting 100-foot plastic spheres; studying the environmental effects upon the spheres, and exploring their use as passive communication reflectors. To create a situation in which optimum use could be made of all the scientific research facilities available, NASA invited the radio industry at large to participate in the project on a voluntary basis. Nor was the invitation restricted to American firms. Through COSP AR, the International Committee for Space Research, NASA circulated the details of the proposed Echo project to scientists throughout the world, well in advance of the proposed launching date originally set for early spring.

Cedar Rapids Communication & Tracking Station.

Following the announcement of the project, Collins Radio Company and its systems subsidiary, Alpha Corporation, actively joined with others in the industry in planning maximum use of the Echo satellites for research. This was not a new area for Collins, since as far back as 1951, the company had participated in experiments using the moon as a passive relay for communications between two points on the earth.

Collins/Alpha participants in Project Echo set for themselves four specific objectives. The first was the evaluation of short-term signal stability. This evaluation is being derived from recordings that will allow a highly precise analysis of signal stability on the over-all path, showing presence and nature of multipath transmission and indicating possible effects from the rotation of the sphere. The second objective is to combine optical and radio tracking for determining refraction of the incoming signal, and to calculate the effect of this aberration on tracking. Objective three is evaluating, by transmit time measurements, the suitability of satellite links for speech and teletype transmission. The fourth aim set up by the participants was aiding NASA with data for exact determination of orbital parameters.

The most conspicuous equipment used in the Collins/ Alpha work on Project Echo is the antenna system. Three 28-foot parabolic antennas were installed; one receiving and one transmitting antenna about ten miles north of the Collins Radio Company plants in Cedar Rapids, Iowa, and the other, a transmitting antenna, at the tracking site adjacent to the Alpha Corporation plant in Richardson, Texas. For receiving, Alpha used a 40-foot diameter Azimuth-Elevation tracking antenna, to which the transmitting antenna was slaved.

The transmitters and receivers used in the experiment were the Collins 240D-l 10-kw power amplifier, coupled with a rack-mounted 310K Exciter Modulator for transmission, and for receiving, an ARP A 108 me Microlock Receiver converted to 955 me. The latter equipment was modified for deep space probing by changing frequency and bandwidth.acid, inflating the limp plastic in a matter of seconds to a firmly rounded, gleaming sphere 100 feet in diameter. The time was 4:02.

At 3:39 a.m. (CST) on August 12, the Delta rocket left the launching pad at Cape Canaveral on the first leg of Project Echo. First stage was a model DM-19 Thor missile, less the re-entry vehicle and guidance equipment. For exactly six minutes after blasting off the pad, the Thor thrusted the rocket up and out over the Atlantic, heading to the southeast at a flight azimuth of ll0°. Then, released by radio command, the second stage - an Aero jet-General AJ 10-ll8 propulsion system with forward instrumentation and guidance compartment - was released, and for the next fifteen minutes propelled the Delta in a long upward coast to the apogee, at an altitude of 1,050.9 statute miles. Precisely at the moment of achieving orbit, and travelling at a speed of 15,646 mph, the third stage payload was released.

The following two minutes saw the metal sphere housing the payload separate itself. At this point, bursting like a Jack-in-the-box from the divided sphere, poured out hundreds of yards of aluminized Mylar plastic to form the Echo balloon. Inside the uninflated plastic sack was a residue of 10 pounds of powdered benzoic acid. On contact with the atmosphere outside the carrier, a sublimation action occurred in the acid, inflating the limp plastic in a matter of seconds to a firmly rounded, gleaming sphere 100 feet in diameter. The time was 4:02.

Back down on the earth, alerted tracking stations, ranging all the way from Trinidad to Australia, one after the other, made fixes on the giant balloon in its flashing orbit.


Antennas at Echo Hill facility (28 foot dia).

At Cedar Rapids and in Dallas, Collins and Alpha engineers picked up the satellite in the tracking antennas at 5:43 a.m. as it began its first pass over the U.S. On the second pass, beginning at 7:48 a.m. and terminating at 8:09 a.m. (CST) they held it intermittently by radio during its course from horizon to horizon. These preliminary fixes were by way of preparation for the major experiment that Collins/ Alpha research hoped to accomplish on the next usable passes of the satellite, scheduled to make a path between Dallas and Cedar Rapids nineteen hours later.

Promptly at 3:04 a.m. on August 13, Echo rose once more in the northwest in its eleventh orbital trip (the third one over the U.S. midwest). The timing was precisely as projected, even before the launch - a tribute to the engineering skill which had put the satellite into a perfect orbit. The tracking antennas were locked on at the transmitting station. In Texas, Al Richmond, the Alpha Corporation's Project Engineer for Echo, spoke into the mike: “This is KK2XlC in Richardson, calling KA2XDV in Cedar Rapids, Iowa. Do you read me, Cedar Rapids?” And the answer came from Cliff Beamer, Collins Research Scientist: “This is KA2XDV in Cedar Rapids, Iowa, calling KK2XlC in Richardson, Texas. We receive you loud and clear.“


East Antenna & Laboratory at Echo Hill Station North of Cedar Rapids, Iowa.

Antennas & Laboratory at Echo Hill Station, looking North.

The first two-way radio voice transmission via artificial satellite was accomplished.

Meantime, other firms were also busily utilizing the satellite as a relay. Participating in the communications experiments officially, as contractors to NASA in Project Echo, were Jet Propulsion Laboratory and Bell Telephone Laboratories. On August 12, these two companies succeeded in relaying a pre-recorded tape from a JPL transmittin~ station in Goldstone, California, to a Bell receiving station in Holmdel, New Jersey. Voluntary participants, in addition to Collins, included General Electric, ITT, Crosley Division of the AVCO Corporation, and the Development Engineering Corporation. All these firms will provide NASA full reports on the data they were able to gather.

Since the Echo launch, Collins research teams have been gathering data during every moment when it is possible to contact Echo in its passes. The signals generated between Cedar Rapids and Richardson are faithfully recorded on Ampex tapes. Then, minute studies are made of each transmission. Constants are checked and variables determined, and each piece of data carefully plotted.

Pending release of the final report - the conclusions of which will be made available both to NASA and to the scientific community in general - it appears that these recorded data will give answers not only to those questions anticipated before the project had begun, but also to several which have arisen out of it.

During the periods when Echo is visible in the night skies, a discernible “scintillating” effect has begun. This is accredited in part to the satellite's loss of its original perfect sphericity. I there a correlation between the scintillation and the radio signal?

As the Echo balloon rotates during orbit, the tiny transmitters at each pole constantly shift position. Will polarized transmitters of this nature create permanent tracking difficulties, and shall they be eliminated from future satellites?

So, while the Echo of Greek legend may have had little to do for man except to show how hurtful were the pangs of disprized love, her modern namesake is fulfilling a much greater role for mankind. The new Echo may well be leading us, by means of “voices” which it catches and bounces back, down new pathways of discovery which will one day make possible radio communications of a scope and reliability almost unimagined.

Collins Signal, Issue 40, Volume 8-4, 1960