In the years following the end of World War II, the possibility of space travel experienced a great surge of interest in Europe and America. This was in large part due to the development of the German A-4 (better known as the V-2) rocket during the war. The A-4, developed and built for the German Third Reich by a team of engineers lead by Wernher von Braun, was the largest rocket developed up to that time and it paved the way for the building of much larger rockets with significantly increased performance. It was recognized by many after the war (as well as by von Braun during the A-4 development) that this new technology would make space travel possible in the near future. As a result, there were a flurry of studies conducted during the late 1940s and early 1950s on the possibility of launching an Earth orbiting satellite.

The German A-4 rocket (better known as the V-2) was developed by a team led by Wernher von Braun and served as the basis of the American Redstone rocket. (NASA/MSFC)

 

Project Orbiter

While the bulk of post-war rocket development, both in the Soviet Union and the United States, centered on the creation of new weapons systems for the military, many involved with these endeavors still had the possibility of space travel in the back of their minds. Von Braun, who was relocated to the United States after the war along with many of his colleagues, was also consumed by his passion for space travel. His writings on the topic in popular American magazines like Colliers during the 1950s and widely-watched documentaries produced by Walt Disney inspired an entire generation with visions of space stations, trips to the Moon, and large expeditions to Mars. All these missions were still far in the future since they required the development of rockets significantly larger than any in existence.

Von Braun’s articles in popular magazines like Colliers helped to increase public interest in space travel in the 1950s. (NASA)

In the near term, von Braun and his team at what was to become the Development Operations Division of the Army Ballistic Missile Agency (ABMA) at the Redstone Arsenal in Huntsville, Alabama had much more modest goals in mind. Advances in the miniaturization of electronics during the late 1940s and early 1950s made it possible for a small satellite with a mass of just a few kilograms to perform useful investigations from orbit. Such a small payload could be launched using rockets only slightly more capable than those currently under development. During 1954 the ABMA team, in cooperation with the California Institute of Technology’s Jet Propulsion Laboratory (JPL) and the Office of Naval Research, began work on a proposal to launch an Earth satellite called Project Orbiter.

The Project Orbiter team shown in a meeting on March 17, 1954 in Washington, DC. Wernher von Braun is the foreground to the right. (NASA/MSFC)

This proposal centered on using a modified Redstone rocket in combination with a cluster of existing solid rocket motors to launch a small satellite into orbit. The Redstone started life as a design study called Hermes C in the late 1940s. The Hermes program was a series of experimental rockets that combined proven German A-4 technology with new American innovations. As such, the Redstone is a direct descendant of the A-4. In July 1950 a feasibility study began for a ballistic missile with a 800-kilometer range based on the Hermes C work.

As the Korean War dragged on, the Redstone program received the highest priority and was redirected. In order to speed development and make it a highly mobile field weapon, the range was reduced to 320 kilometers and it was decided to use a smaller Rocketdyne-built engine based on the one used by an early version of the rocket booster employed by the USAF Navaho supersonic cruise missile then under development. On April 8, 1952 this new rocket was designated Redstone after the Redstone Arsenal. Development proceeded quickly and the first of what would be 37 test flights was launched on August 20, 1953.

The first Redstone test flights, like round RS-6 shown here at launch in October 1954, lifted off from the then new Launch Complex 4 (LC-4) at Cape Canaveral. (NASA/MSFC)

For Project Orbiter, a modified version of the Redstone would be employed. While the diameter of the missile remained at 1.8 meters, the propellant tanks would be lengthened by 1.65 meters to increase their volume. This increased the burn time for Redstone’s engine from 121 to 155 seconds. The Redstone’s Rocketdyne A-5 production engine, which normally burned alcohol and liquid oxygen to produce 334 kilonewtons of thrust, was modified to become the A-7 which used what the Army called “Hydyne” (a corrosive mixture of unsymmetrical dimethylhydrazine and diethylene triamine) as a fuel to produce 369 kilonewtons of thrust. The larger propellant load, greater thrust, and improved engine efficiency increased the performance of the rocket sufficiently to make it part of a viable satellite launch vehicle.

The final configuration of ABMA’s Jupiter C in its satellite launch configuration that was later known as the Juno I. Click on image to enlarge. (NASA)

Mounted on top of this modified Redstone would be a high speed assembly consisting of an instrument compartment and a cluster of off-the-shelf solid rocket motors. Originally a cluster of 37 motors used in the Loki antiaircraft missile were considered for this application. But in order to simplify the design and increase the assembly’s reliability, eventually it was decided to use a cluster of 15 scaled-down versions of the JPL-developed rocket motor used in the Sergeant surface-to-surface tactical missiles. Each of these motors would be 15 centimeter in diameter, 1.2 meters long and generate 7 kilonewtons of thrust for 5 to 6 seconds. The cluster would be held in an electrically-driven spinning tub mounted on top of the modified Redstone. The cluster was spun to provide gyroscopic stability and to even out any performance variations in the proposed solid rocket motors which were quite primitive by today’s standards. This Redstone-based launch vehicle had a total length of 21.7 meters and a lift off mass of 29,000 kilograms.

This drawing shows the arrangement of the three upper stages of the Jupiter C/Juno I upper stages known as the high speed assembly. Click on image to enlarge. (ABMA)

In its satellite launcher configuration, the upgraded Redstone first stage would loft the high speed assembly above the atmosphere whereupon it would separate from the cluster. The spinning aluminum tub would then coast for a predetermined period of time using variable thrust, compressed gas thrusters to maintain proper attitude. At the right moment, the outer ring of 11 rocket motors would ignite to send the other upper stages and payload on their way. Immediately after burnout, a third stage made up of a cluster of three motors mounted inside this ring would ignite. The final stage in this rapid fire sequence, consisting of a single rocket motor, would then ignite to place the small payload into Earth orbit. In theory this rocket could place 9 kilograms into orbit but further improvements later raised this to 11 kilograms. The primary advantage of this proposal over its competitors was that it made use of existing technology and proven hardware. As a result, many felt that Project Orbiter would be available to launch a satellite before any other project.

 

Death of Project Orbiter

In September 1954 the joint Army-Navy Project Orbiter proposal to launch a single satellite was submitted to the Department of Defense (DoD) for consideration. At about this same time, there was a building effort in scientific circles to organize the International Geophysical Year – an international scientific cooperative effort to study the Earth and its interaction with the Sun that would run from July 1, 1957 to December 31, 1958. With the US considering a commitment to launch a satellite during the IGY, the US Air Force (USAF) and the Naval Research Laboratory (NRL) submitted their own satellite proposals as well. With three choices before him, Assistant Secretary of Defense Donald A. Quarles deferred the decision to an Advisory Group on Special Capabilities.

NRL’s Vanguard satellite project got the go ahead to be America’s first official satellite program over ABMA’s Project Orbiter. Click on image to enlarge. (NASA)

On September 9, 1955 this group choose the NRL proposal which was eventually called Vanguard (see “Vintage Micro: The Original Standardized Microsatellite”). While Project Orbiter made the greatest use of off-the-shelf hardware and had the best chance to get a satellite into orbit first, the Eisenhower administration made it clear that they wanted to use as little military hardware as possible to launch America’s IGY satellite. This was to give the project as civilian a look as possible to ease establishment of the concept of overflight rights for Earth-orbiting satellites (making it easier for later military satellites, then secretly under study, to fly their missions). The Eisenhower Administration also wanted to minimize any potential interference between the satellite program and vital defense projects like the Army’s Redstone or the USAF proposed use of their Atlas ICBM then under development (see “The First Atlas Test Flights”). Another perceived weakness in the Project Orbiter proposal was that it would launch only a single satellite with no follow up. Of course this could have been easily remedied with additional resources to build hardware for more flights but it was felt that this could have had deleterious consequences for the Redstone development program.

Major General Bruce Medaris (left) and Wernher von Braun were ultimately responsible for getting America’s first satellite into orbit. (US Army)

With Project Orbiter officially shelved, development of von Braun’s proposed satellite launch vehicle was redirected in September of 1955 in an attempt to keep it alive in another guise. In addition to the Redstone, the ABMA, under the command of Major General Bruce Medaris, was developing the Jupiter IRBM (Intermediate Range Ballistic Missile). With a range of 2,800 kilometers, Jupiter’s warhead would have to withstand much more extreme conditions upon reentry into the Earth’s atmosphere than the payloads of earlier, shorter range missiles. In-flight testing of this new warhead-laden entry vehicle was needed to verify its design but a purpose-built rocket for this task was not yet available. As a stop gap measure, a modified version of von Braun’s satellite launcher was proposed. While it was not powerful enough to loft the actual warhead, the rocket would be capable of accelerating a one-third scale RTV (Reentry Test Vehicle) with a mass of 140 kilograms to hypersonic velocities. The only major change required to von Braun’s satellite launcher was the removal of the fourth stage and the installation of an adapter for the RTV.

The Jupiter C shown configured for RTV flights in support of the Jupiter IRBM program. Click on image to enlarge. (ABMA)

From the start, the development of this modified Redstone proceeded so that the satellite launch option would be preserved. This rocket was designated Jupiter C (“C” standing for “Composite”) to help disguise its heritage under the Jupiter program umbrella. This would not be the first Redstone to fly in support of Jupiter development, however. Starting in March 1956, modified Redstone missiles designated “Jupiter A” commenced flight testing key Jupiter IRBM components such as the guidance system in preparation of the first actual Jupiter test flights a year later. As development of the Jupiter C proceeded ostensibly to support the IRBM project, Medaris and von Braun continued to lobby civilian and military leaders in Washington to allow them to launch a satellite.

 

Jupiter C Flights

Work on the Jupiter C proceeded quickly at ABMA and JPL in order to meet the tight development schedule of the Jupiter program. By the end of the summer of 1956, the Jupiter C was ready for its first test flight only one year after the project was authorized. The stated objectives of this first flight included testing of the staging techniques for the three-stage configuration required for subsequent Jupiter RTV flights, verify the structural integrity of the Jupiter C as well as the modifications to the Redstone and its engine for the longer burn times with the more potent (and chemically reactive) Hydne fuel substituted for alcohol. In addition, the use of pyrotechnic flares and miniaturized radio gear for tracking the missile and payload during its flight would be investigated. The goal for the flight was to reach ranges of at least 748 kilometers with the first stage, 1,880 kilometers with the second stage and a total range of at least 4,020 kilometers.

The JPL-developed payload for the Jupiter C Round 27 test flight was the forerunner of the first Explorer satellites. Click on image to enlarge. (ABMA)

This first test flight would use the Jupiter C designated Round 27. But instead of carrying a RTV, this three-stage rocket was flown in its satellite launch configuration with an inert fourth stage filled with ballast mounted under a protective shroud. The active payload for this flight, developed by JPL, was housed in a cylinder with a diameter of 15 centimeters topped by a cone with a total length to about 90 centimeters. This payload was mounted on top of the inert fourth stage and protruded through a protective aerodynamic shroud. This payload housed a pyrotechnic flash assembly, a miniaturized DOVAP (Doppler Velocity and Position) transponder to be used after booster burnout and a ten-milliwatt Microlock beacon. The Microlock system, which had been developed by JPL for satellite applications, would carry five channels of telemetry to provide engineers with data on the performance of the Jupiter C high speed assembly. The total mass of the JPL payload and ballast was 39.2 kilograms.

According to some popular accounts of this initial test flight, the ballast was intentionally carried on this flight to prevent von Braun from “accidentally” launching the payload into Earth orbit during this test flight. Having been turned down twice again during 1956 for authorization, von Braun’s desire to launch a satellite was hardly a secret. Still, there is no evidence to suggest that von Braun and his team had any intention of violating their explicit orders not to launch a satellite and the ballast was carried simply to approximate the mass properties of a loaded fourth stage for this test flight.

Jupiter C Round 27 being prepared for launch on September 20, 1956 from LC-5 at Cape Canaveral, Florida. (US Army)

At 1:47 EST on September 20, 1956, Jupiter C Round 27 lifted off from Launch Complex 5 at Cape Canaveral, Florida and headed downrange at an azimuth of 100° east of true north. As the rocket ascended, the spin rate of the high speed assembly was increased from its initial 549 rpm to 810 rpm to avoid vibrational resonances with the missile’s structure as its propellant tanks emptied. While the pyrotechnic flashes deployed by the payload were not visible during ascent because of heavy cloud cover and a full Moon, the tracking station at Cape Canaveral clearly received the signals from the Microlock beacon and DOVAP transponder. About 196 seconds after launch, the downrange tracking station on Grand Turk Island also began to receive transmissions from the quickly ascending Jupiter C payload.

Telemetry and tracking indicated that all three stages of the Jupiter C worked as planned with the payload reaching a peak altitude of 1,097 kilometers and travelling over a total range of 5,390 kilometers – a record at the time for a launch from Cape Canaveral that would not be broken until long range ICBM testing started. The principle objectives of the flight were all met with the DOVAP transponder and Microlock beacon tracked throughout the flight for a total of 16 minutes, 47 seconds from Cape Canaveral and until 19 minutes and 30 seconds after launch from Grand Turk Island. Von Braun and his team now had the means of launching a satellite into orbit. In fact, if Round 27 had carried an active fourth stage and a properly sized payload, the US could have orbited the world’s first satellite with only slight modifications to the Jupiter C.

A Jupiter C RTV being prepared for a pre-launch spin test. (US Army)

With this successful test flight completed, worked turned towards Jupiter C RTV launches. On May 15, 1957 at 2:55 EST Jupiter C Round 34, the first to carry a scaled Jupiter IRBM RTV, successfully lifted off from LC-6 at Cape Canaveral. Although all three stages of the rocket fired, a guidance system malfunction and the failure of the third stage to separate from the RTV resulted in the payload reaching a peak altitude 164 kilometers higher than the intended 404 kilometers and travelling 587 kilometers short of its planned 2,040-kilometer range. Coupled with an azimuth error in the trajectory, the RTV missed its target area downrange in the Atlantic Ocean and the payload was not recovered. Radar tracking, however, indicated that the RTV’s new ablative heat shield worked as planned and that it had survived reentry intact.

With this second successful flight of the Jupiter C, the press started taking greater interest in von Braun’s Jupiter C satellite proposal. Of course von Braun was all too eager to extol the virtues of his system in comparison to the America’s “official” IGY satellite program, Vanguard, which was making painfully slow progress at the time. Since the Defense Department’s public position was that there was no military benefit in space exploration (never mind that the satellite “problem” was already being solved by Vanguard), they did not want defense dollars being spent on space programs. As a result, military leaders took a dim view of von Braun’s proselytizing. Finally on July 29, 1957 the Pentagon issued a directive to the three branches of the military forbidding anyone from discussing with the press space, space technology and space vehicles. The NRL’s Vanguard program was of course exempt from the directive since, on paper at least, they received their money and direction from civilian agencies like the National Science Foundation and the National Academy of Sciences.

Jupiter C Round 40 being prepared for the final launch of an RTV in support of the Jupiter IRBM program. (US Army)

The third flight of the Jupiter C, Round 40, was finally launched at 1:59 EST on August 8, 1957 from LC-5. Despite some minor issues, the RTV reached a peak altitude of 600 kilometers before arcing back into the atmosphere at a velocity of 19,300 kilometers per hour. The RTV survived reentry and came down by parachute 1,866 kilometers downrange where it was quickly recovered out of the Atlantic by the USS Escape – one of the US Navy’s Diver-class rescue and salvage ships. The RTV was subsequently presented by President Eisenhower on national television with the claim of it being the first object to be successfully recovered from space.

President Eisenhower shown with the RTV recovered from the August 8, 1957 flight of Jupiter C Round 40. (US Army)

With this successful third flight, the Jupiter C program had met all of its objectives and the program was declared completed. Future test flights of warhead nosecone designs would use purpose-built rockets like the USAF X-17 which had already started flights. The remaining three Jupiter C rockets, including Round 29 which was already in a satellite launcher configuration since it was a backup to the original flight of Round 27, were consigned to storage in the hopes that the Eisenhower administration and the Department of Defense would soon authorize a satellite launch.

 

Satellite Launches Authorized

After the completion of the Jupiter C program, von Braun and Medaris continued to press for permission to launch a satellite as part of a six-vehicle program that would serve as a backup for Vanguard. The proposal would have probably languished indefinitely had fate not intervened. As luck would have it, von Braun and Medaris were attending a cocktail party with Secretary of the Army Wilbur Brucker and the new Secretary of Defense, Neil McElroy, in the officer’s club at the Redstone Arsenal on the evening of October 4, 1957. In the midst of the festivities the announcement of the launch of Sputnik was made. One can only imagine von Braun’s frustration knowing he could have placed a satellite into orbit a year earlier if he had only received the required permission from his superiors. Von Braun immediately made his now famous pitch to McElroy to launch a satellite using a surplus Jupiter C within 60 days of authorization. Medaris suggested that 90 days would be a more realistic goal.

Secretary of Defense Neil McElroy (on the left in the front) getting a tour of the Redstone Arsenal in Huntsville, Alabama. (US Army)

A series of meetings ensued culminating in a three-day long meeting starting on October 23 at Fort Bliss, Texas where von Braun and Medaris presented their proposal to the Army Scientific Advisory Panel. As a result of this meeting, ABMA’s confidence in their hardware, and the public’s strong negative reaction to the Soviet satellite launch, Brucker was now much more supportive of the project. On October 27 the Advisory Group on Special Capabilities, now under Homer J. Stewart, approved the launching of two satellites using a four-stage version of the Jupiter C. To further distance the project from military programs, this satellite launch vehicle was now officially designated Juno I, although the “Jupiter C” moniker more familiar to the press was still frequently used. On November 8, just five days after the launch of the Soviet’s second satellite, Sputnik 2, Secretary of Defense McElroy finally authorized an initial two-satellite program with the first launch to take place in March of 1958. Within a month $3.5 million had been earmarked for the launches and, as result of the advance state of preparation, the date of the first flight was pushed up to the end of January 1958.

Left to right, William Pickering (JPL), James Van Allen (University of Iowa) and Wernher von Braun (ABMA) shown holding a model of Explorer 1 at a post-launch press conference. (NASA/JPL)

With the failure of the Vanguard TV-3 flight on December 6, 1957, von Braun and the ABMA finally got their chance to launch the first American satellite, Explorer 1, using Juno I Round 29 on the night of January 31, 1958. If the ABMA team’s plans had not been restricted by the Eisenhower Administration, Round 27 could have conceivably orbited the first satellite the year before before the Soviet Union launched Sputnik and long before NRL successfully orbited its first Vanguard satellite (see “Vintage Micro: The Original Nanosatellite”). The subsequent history of the early Space Age would likely have unfolded very differently as a result.

 

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Related Video

Here is an excellent JPL/ABMA documentary film on the events leading up to the launching of Explorer 1.

 

Related Reading

“Vintage Micro: The Original Standardized Microsatellite”, Drew Ex Machina, July 5, 2014 [Post]

“Vintage Micro: The Original Nanosatellite”, Drew Ex Machina, February 5, 2015 [Post]

“The First Atlas Test Flights”, Drew Ex Machina, June 11, 2015 [Post]

“Vintage Micro: The Talking Atlas”, Drew Ex Machina, December 18, 2014 [Post]

“Redstone: The Missile That Launched America into Space”, Drew Ex Machina, April 26, 2016 [Post]

 

General References

David Baker, The Rocket, Crown Publishers, 1978

Josef Boehm, Hans J. Fichtner, and Otto A. Hoberg, “Explorer Satellites Launched by the Juno 1 and Juno 2 Carrier Vehicles”, in Astronautical Engineering and Science, edited by Ernst Stuhlinger, Frederick I. Ordway III, Jerry C. McCall, and George C. Bucher, McGraw-Hill Book Co., pp. 215-239, 1963

Dwayne A. Day, “New Revelations About the American Satellite Programme Before Sputnik”, Spaceflight, Vol. 36, No. 11, pp. 372-373, November 1994

J.D. Hunley, Preludes to US Space-Launch Vehicle Technology: Goddard Rockets to Minuteman III, University Press of Florida, 2008

William H. Pickering, “History of the Juno Cluster System”, in Astronautical Engineering and Science, edited by Ernst Stuhlinger, Frederick I. Ordway III, Jerry C. McCall, and George C. Bucher, McGraw-Hill Book Co., pp. 203-214, 1963

Wernher von Braun, “The Redstone, Jupiter, and Juno”, in The History of Rocket Technology, edited by Eugene M. Emme, Wayne State University Press, pp. 107-121, 1964

Allen E. Wolfe and William J. Truscott, Juno Final Report Volume I – Juno I: Re-entry Test Vehicles and Explorer Satellites, JPL Technical Report No. 32-31, September 6, 1960