Ask any space enthusiast about “The Moon Race” (especially those of a particular age like myself) and the competition between the United States and the old Soviet Union to land crews on the Moon immediately comes to mind. While the US clearly won that race with the successful mission of Apollo 11 in July 1969, there was an even more intense race to the Moon a decade earlier which is often overlooked today. After the first satellites were launched into Earth orbit, both the US and Soviet Union were involved in an intense competition to reach the Moon first using small automated probes launched on the largest rockets of the day. And unlike the later Moon race, this head-to-head competition involved launches literally hours apart in a bid by each nation to take the high ground in the opening years of the Space Age.

The Beginnings of the Soviet Lunar Program

The launching of the first Sputniks under the direction of Soviet aerospace pioneer, Chief Designer Sergei Korolev of OKB-1 (the Russian acronym for “Experimental Design Bureau 1”), caused such a stir in the West that Soviet Premier Nikita Khrushchev could not help but exploit the propaganda value of Soviet space missions. But with the successful launching of the first three Sputnik satellites during the first months of the Space Age, all the “easy” space spectaculars had already been achieved. By the beginning of 1958 the Soviet Union’s infant space program had set its sights on the Moon.

Even in the opening months of the Space Age, Soviet engineers and scientists had already spent years studying potential lunar missions. While serious work on Earth satellites was moving forward during the early to mid-1950s, a handful of Soviet theoreticians and designers were quietly making the first tentative steps required to explore the Moon. At this point in time, the most basic questions had to be answered: What sort of missions were needed? What are the velocity requirements for these missions? How long would these missions take?

Over time a number of missions types were identified and investigated including lunar orbiters and “cycling stations” that would orbit continuously between the Earth and Moon. By far the most advanced concept publicly announced by the Soviet media was revealed on April 26, 1955 by Radio Moscow and later detailed in a Russian-language magazine article by Yuri S. Khlebtsecich the following November. Plans were outlined for a radio-controlled lunar “tankette” that would be launched by a large, multi-stage rocket. This remote-controlled rover could make observations over large stretches of the lunar surface and report its findings back to Earth. However, this sort of mission was well over a decade away.

Lunar missions were always part of Korolev’s space plans. When his satellite program was approved by the Soviet government in the beginning of 1956, work on more advanced missions also began to move forward not only at Korolev’s OKB-1 but at other institutions as well. Among these was a group at MIAN (Mathematical Institute of the Academy of Sciences) under Korolev’s friend and ally, Academician Mstislav V. Keldysh, who began making detailed calculations of over 600 trajectories to define precisely the requirements for various lunar missions.

Based on scientific objectives and the projected availability of technology, a three-step strategy for long-term lunar exploration was eventually devised. The first step, which could make use of current or soon to be available technology, consisted of a series of flyby, impact, or hard landing missions. With a few more years of development, the second step would become possible. In this phase, payloads would be delivered to the lunar surface and into orbit. The last phase, which would require many more years of work, involved delivering automated probes to the Moon and returning a payload of surface samples or exposed film back to Earth.

In April of 1957, the project department for the development of spacecraft at OKB-1 under Mikhail Tikhonravov submitted a report on the exploration of the Moon and the launching of manned satellites. The one point that was made clear immediately was the need to build a launch vehicle more capable than the existing derivatives of the two-stage R-7 ICBM (known internally as the 8K71 and as the SS-6 or Sapwood in the West) that would launch the first satellites (see “Sputnik: The Launch of the Space Age”). As early as 1955, Korolev had anticipated this need and considered attaching a third stage on top of the basic 8K71 to greatly improve its performance. By the summer of 1957 development of this stage, called Blok E, had begun.

The Gas Dynamics Laboratory at OKB-456 under the direction of Valentin Glushko was given the assignment of developing an engine, designated RD-109, for the Blok E. Glushko and his engineers felt that a fuel other than kerosene, which the 8K71 used, should be employed. Ultimately they chose UDMH (unsymmetrical dimethyl hydrazine). Since there was little experience in developing a large engine to burn such an exotic (not to mention corrosive and toxic) fuel, Korolev felt that developing the RD-109 would take much longer than Glushko expected. In order to avoid delays and despite Glushko’s protests, Korolev started parallel development of his own engine, the RO-5, at OKB-1 that burned the more conventional fuel, kerosene. Based on the S1.25800 steering engines OKB-1 developed for use with the RD-107 engine that powered the 8K71, the RO-5 would only be half as powerful as Glushko’s RD-109. Despite its smaller size, the RO-5 still provided the performance needed to reach the Moon.

The Soviet Program Moves Forward

With the successful launch of the first Sputnik and the furor that ensued, Khrushchev bypassed the existing chain of command and quickly conferred directly with Korolev to determine what other space spectaculars were possible. With Khrushchev’s backing, Korolev’s dreams for space exploration were to advance much more quickly than he could have ever imagined. The launching of additional satellites, such as Objects PS-2 and D (which became Sputnik 2 and 3, respectively – see “Sputnik 2: The First Animal in Orbit” and “Sputnik 3: The First Orbiting Geophysical Laboratory”), was immediately approved. Resources were also made available for the development of manned spacecraft as well as probes to the Moon and planets. Upon returning from his meeting with the Soviet leader, Korolev directed Tikhonravov and his project department to begin work on vehicles to explore the Moon. Tikhonravov delegated the task of designing and building the first Soviet lunar probes to a team of young engineers and scientists at OKB-1 affectionately known as the “Lunatics”.

By December of 1957 the outline for the two lunar launch vehicles based on the 8K71 ICBM, had been worked out. Both launch vehicles would use a stripped down version of the R-7 designated 8K71/III. The first rocket, the 8K72 would use a Blok E third stage built around Korolev’s RO-5 engine which by this time was being jointly developed with OKB-154 under Semyin Kosberg. This engine produced 49.9 kilonewtons of thrust for 450 seconds by burning about 6.93 metric tons of kerosene and LOX (liquid oxygen) held in separate toroidal tanks. This Blok E third stage, called 8K72E, was 2.66 meters in diameter and stood 5.0 meters tall with its conical nose shroud in place. It was attached to the top of the 8K71/III “basic packet” by a simple open truss which allowed the exhaust of the engine to escape as it ignited. Depending on the mission profile, the 8K72 could send up to about 400 kilograms of useful payload on a direct ascent trajectory to the Moon. This would be the most powerful launch vehicle of its day capable of lifting over an order of magnitude more payload to the Moon than any American rocket soon to be available (see “The Largest Launch Vehicles Through History”).

The second lunar launch vehicle, called the 8K73, would have a Blok E third stage incorporating the much larger RD-109 being developed by Glushko’s OKB-456. The RD-109 produced 101.6 kilonewtons of thrust and would consume 8.05 metric tons of UDMH and LOX during a 330 second burn. Despite the different engine, the 8K73E stage’s construction was very similar to the 8K72E. The 8K73E stage had the same diameter as the 8K72E but was 1.1 meters taller to accommodate the larger propellant load. With 16% more propellant, an engine that was 2% more efficient, and a 26% shorter burn time which cut gravity losses during a direct ascent towards the Moon, the 8K73E was better than the 8K72E for missions to the Moon and beyond with a lunar payload capability of over 550 kilograms.

In December of 1957 Korolev formally submitted his lunar plans for approval. The primary objective of the first mission would be to impact the Moon. In order to determine what instrumentation should be carried on this and subsequent lunar missions, Korolev met with Soviet astronomers to get their input. Given the secrecy that enveloped the development of Soviet space hardware and the fact the Space Age had just begun, these astronomers were amazed to discover that a flight to the Moon was not only possible but almost at hand. Eventually it was decided that the first lunar probes would measure magnetic fields, assess the radiation environment, and determine the density of micrometeoroids during its flight. These missions would only require a simple spheroidal probe about 1.2 meters in diameter with a mass of about 170 kilograms and no attitude control that could be quickly developed.

This Moon probe, designated E-1 (“E” being the next letter in the alphabet after the Sputnik 3 Object “D”), would use the 8K72 which was scheduled to make its first test flight in June or July of 1958. In order to maximize the payload, the launch was restricted to a two to three-minute window during a three-day period when the Moon was either about 10 or 23 days old, depending on the season. A short flight time of about 38 hours would ensure that the probe would be visible from the Soviet Union during its lunar encounter. This type of fast trajectory also had the benefit of minimizing the effects of aiming and final velocity errors. To help reduce the latter, the 8K72E stage would use radio commands to shutdown its RO-5 engine when the proper velocity had been achieved.

In the original proposal, post-launch tracking of the receding lunar probe would be aided by either an inflatable 30-meter in diameter aluminized balloon or, as proposed by Soviet astronomer Professor Iosef Shklovsky, an artificial comet of lithium or sodium vapor released from the spent Blok E stage. Depending on the available payload margin of the 8K72, additional engineering and scientific equipment could be carried by the Blok E to supplement investigations by the E-1 probe. Korolev scheduled this flight to take place around August or September of 1958.

The next set of missions would use more advanced, three-axis stabilized probes designated E-2 and E-3. These probes, with a mass of about 280 kilograms each, would image the unseen farside of the Moon using an automated photographic system. In addition to this primary instrument, these probes could carry other sensors to continue investigations of the cislunar environment. Because of the alignments of the Earth, Moon, and Sun these missions required, the E-2 and E-3 could only be launched in October-November or April-May. The development of these more sophisticated probes, which was made the responsibility of Yuri Mozzhorin, would require more time than the E-1. If all went according to schedule, the 8K73 would be available to launch the first of these probes in October or November of 1958.

One last lunar “probe” that was considered at this time was the E-4. Its mission would be to set off a nuclear explosion upon impact with the lunar surface that could be viewed from the Earth leaving no doubt that a Soviet probe had reached the Moon. Weighing in at about 400 kilograms, the E-4 would require the lifting capability of the 8K73. While an interesting publicity stunt, Korolev was not enthusiastic about beginning an era of lunar exploration with the nuclear bombardment of the Moon. There were also genuine concerns about the visibility of a nuclear detonation on the airless Moon. Ultimately the E-4 was cancelled. After these lunar missions Korolev intended to move on and use the 8K73 to launch the first probe to Venus, designated V1, in June of 1959 followed by launches to Mars the following year (see “The First Mars Mission Attempts” and “Venera 1: The First Venus Mission Attempt”). Korolev’s aggressive plans for lunar exploration were approved by the Soviet government on March 28, 1958.

American Plans to Reach the Moon

Dreams of reaching the Moon were hardly confined to the Soviet Union in the years leading up to the beginning of the Space Age. There were many studies made in the West about lunar missions during the post-war years which gripped the public’s imagination. Among these were grandiose proposals made by German rocket pioneer, Wernher von Braun, who had been relocated to the US after World War II to develop missiles for the US Army. 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.

More modest (and realistic) proposals for lunar missions which could be flown in the near term using available technology were studied by a wide range of groups. In the two years leading up to the launch of Sputnik and the beginning of the Space Age, serious proposals included one by Aerojet Corporation (which today is part of Aerojet Rocketdyne) to use a five-stage version of its Aerobee sounding rocket to send a probe to the Moon as well as Ford’s Aeronutronic division using a lash up of the Vanguard and X-17 rockets, Martin (which today is part of the aerospace giant Lockheed Martin) using their Titan ICBM then under development and the USAF employing the rocket booster of the Navaho cruise missile (then the largest American rocket to fly) combined with the Redstone and solid upper stages. The RAND Corporation proposed a lunar impactor launched using a version of the Atlas ICBM and the Massachusetts Institute of Technology studied recoverable lunar probes.

There were even serious proposals to detonate a nuclear weapon on the surface of the Moon just as had been proposed to be done by the Soviet E-4 probe. One such proposal was outlined in an article in the June 1957 issue of Scientific American written by the designer of the innovative Atlas ICBM, Krafft Ehricke, and Noble prize winning physicist, George Gamow. Called “Cow” (referring to the nursery rhyme line, “the cow jumped over the Moon”), one of their proposed flights would detonate a nuclear device on the lunar surface with a second probe following close behind to pass through the resulting debris cloud to retrieve lunar samples for return back to the Earth.

After the furor caused by the launching of the first Soviet Sputniks, some of these proposals started to receive serious attention by the American Department of Defense (DoD). In the hopes of quickly unifying the military’s research projects and securing a major share of the nation’s future space program for the DoD, Secretary of Defense Neil McElroy established the Advanced Research Projects Agency (ARPA) on February 7, 1958. ARPA was charged with coordinating all the DoD’s advanced research, including their space projects, to help eliminate duplicate efforts among the various branches of the service. Since the entire space program at this time was connected in some way to the military, by default ARPA would be in charge of almost all aspects of the American space program until Congress and the Administration made other arrangements.

On March 27, 1958 (just a week after the Soviet government had secretly approved Korolev’s lunar probe plans), President Eisenhower approved McElroy’s plan for ARPA to undertake its first series of space missions. The most ambitious of these was labeled “Operation Mona” which called for the launching of five probes to the Moon in hopes of beating the Soviet Union to our neighbor. Three of these attempts would be sponsored by the USAF Ballistic Missile Division while the von Braun’s group at the Army Ballistic Missile Agency (ABMA) would be responsible for the last two. ARPA believed that a successful military lunar mission would not only help the US leap frog ahead of the Soviet Union in the space race but also add credibility to the military presence in space. It was felt by some that these missions could help prevent any civilian space agency that Congress might create from taking an important share of the space program from the DoD. In addition, the long-distance guidance and tracking experience gained in the project would be useful for future scientific and weapons programs.

The USAF Moon Probes

The USAF would have the first shot at the Moon with the more ambitious of the two sets of ARPA lunar probes under the name of “Project Able-1”. For these missions, the USAF planned to use their new Thor-Able rocket which was cobbled together from existing rocket components. The first stage of this rocket was the Thor intermediate-range ballistic missile (IRBM) which, as a weapon, had a range of 2,600 kilometers. The Thor, built by the Douglas Aircraft Company (which became McDonnell-Douglas and much later merged with Boeing) for the USAF, was about 18.6 meters long and 2.4 meters in diameter at the base. The Thor incorporated a Rocketdyne MB-3 power plant burning kerosene and liquid oxygen (LOX) to produce 668 kilonewtons of thrust.

In the Thor-Able configuration, Thor’s one-ton nuclear warhead was replaced with an adapter upon which the 1.88 metric ton upper stages were mounted. These stages were modified versions of the ones originally developed for the Navy’s Vanguard program (see “Vanguard TV-3: America’s First Satellite Launch Attempt”). The Vanguard second stage built by Douglas was modified by the builders of the USAF lunar probes, STL (Space Technology Laboratory – a division of what would become TRW), for the Thor-Able program. In the Able configuration, the second stage retained its original 0.85 meter diameter but it was shortened to 5.8 meters to optimize its size for the Thor-Able mission. The second stage’s original Aerojet General AJ10-37 liquid propellant rocket engine was also replaced with the substantially improved AJ10-41 engine which generated 35 kilonewtons of thrust burning UDMH and nitric acid – the same fuel that Glushko’s OKB-456 planned to use for the new Soviet lunar launch vehicle upper stage. Before it had been selected for its lunar mission, a two-stage version of this rocket, designated Thor-Able 0, had been selected by the USAF for high-speed reentry testing of proposed ICBM reentry vehicle designs. STL had submitted the proposal for what became known as ARTV (Able Reentry Test Vehicle) on November 1, 1957 with work beginning in earnest the following month.

The third stage of what would become known as the Thor-Able 1 was the fiberglass-cased X-248 solid motor built by Allegany Ballistics Laboratory (which today is operated by ATK under contract from the US Navy). This innovative lightweight motor was an evolutionary outgrowth of work for the US Navy to develop a backup for the more conventional motor developed by the Grand Central Rocket Company for the Vanguard program. The X-248, which generated 12.5 kilonewtons of thrust for 38 seconds, was later incorporated into several other rocket designs including a high performance version of the Vanguard. Altogether, the Thor-Able I was 27 meters tall from its base to the top of its hemispherical “mushroom cap” payload fairing. Theoretically, the Thor-Able I could place 160 kilograms of payload into a 480-kilometer high orbit or up to 39 kilograms into a direct ascent escape trajectory to the Moon or beyond.

The USAF lunar probe, which was frequently labeled as “stage 4” in STL’s Thor-Able design, had the ambitious goal of being the first spacecraft to orbit the Moon less than a year after the first satellites had been launched into Earth orbit. Under contract by the USAF, STL built three 38-kilogram spin-stabilized probes each carrying 18 kilograms of scientific instruments. The orbiter consisted of a wide cylindrical belt with a diameter of 74 centimeters joining two flattened fiberglass cones. At the end of the bottom cone was a ring of eight vernier solid rockets which could be fired to correct the probe’s trajectory. At the other end of the 76-centimeter tall probe was a single Thiokol TX-8 solid rocket motor that would be fired about 65 hours after launch to slow the probe by about 850 meters per second and into lunar orbit. Without any attitude control system, the spinning probe would essentially maintain a constant orientation in inertial space after its release from the launch vehicle’s final stage. Removable black and white stripes applied to the probe’s exterior before launch were used for passive thermal control to maintain the internal temperature between 16° and 29° C.

The probe’s wide belt carried the control systems, batteries, radio, and scientific instruments to measure magnetic fields, radiation, and micrometeorites. The STL probe also carried a simple line-scan camera designed and built by the Naval Ordinance Test Station (NOTS) similar to units built for the NOTSNIK satellite in the hopes of obtaining the first close-up images of the Moon (see “NOTSNIK: The First Air-Launched Satellite Attempts”). This camera had a mass of only 400 grams and consisted of a small parabolic mirror that focused infrared radiation received from the Moon onto a special detector cell. The scene could then be slowly built up one line at a time as the probe moved in relation to the Moon. The camera would be activated automatically after the camera detected the light of its target following the firing of the retrorocket. Once activated, there would be sufficient battery power available to operate the camera and its dedicated 50-watt transmitter for a few hours – hopefully long enough to secure and transmit a single crude image of the Moon via the USAF’s primary tracking station in Hawaii.

Because of the mission requirements, the fixed orientation of the probe and the crude nature of the probe’s thermal control system, launches to the Moon were only possible during a four-day period each month with launch windows lasting no longer than 35 minutes. On the remote chance that the probe should accidentally impact the Moon, the spacecraft was decontaminated to minimize the chances that organisms from Earth would corrupt any future biological investigations on the Moon.

A Bad Start

Just as Korolev had feared, the development of the RD-109 engine dragged on much longer than planned. This delay along with problems with the R-7 and its engines uncovered during development flights and bench tests threatened to scuttle Korolev’s original optimistic lunar exploration schedule. But by May 1958 the first 8K71/III, serial number B1-14, had been modified in the shops at OKB-1 outside of Moscow and in early June it was delivered to the NIIP-5 range in Kazakhstan (which would eventually go by the name of the Baikonur Cosomdrome). Because of the lagging development of the RO-5, an engine-less Blok E equipped only with telemetry and control systems would be carried on this suborbital test flight to verify the overall design and structural integrity of the new rocket. The first 8K71/III finally lifted off on July 10, 1958. While there are conflicting accounts of what exactly happened, all the sources agree that the test was unsuccessful.

After a half year of intensive effort by the staff at STL and other USAF contractors, the USAF lunar probe was ready for launch with the first Thor-Able 1 rocket erected on Pad A at Launch Complex 17 (LC-17A) at Cape Canaveral, Florida. A quarter of the way around the planet, Soviet engineers were busy preparing their first E-1 lunar probe in the hopes of beating the Americans. Erected on its pad at Area 1 at the NIIP-5 Test Range was the first 8K72 launch vehicle serial number B1-3. Despite the problem encountered with the development of the 8K72, the imminent launch of the USAF probe and pressure from superiors to beat the Americans forced Korolev to attempt a launch anyway. A neck-and-neck race to be first to the Moon had materialized.

Celestial mechanics and trajectory requirements dictated that the USAF Project Able 1 would be first to attempt a launch. On August 17, 1958 at 8:18 AM EDT (12:18 GMT), Thor 127 lifted off from LC-17A and into a clear Florida sky carrying the Able-1 stages and payload. For the first time in the history of our species, we were attempting to reach the Moon. All seemed to be going as planned as the Thor-Able accelerated towards space. But as the quickly rising rocket passed an altitude of 15 kilometers some 73.6 seconds after launch, it exploded. Transmissions from the still active Pioneer probe were received until it and the remains of the Thor-Able plummeted into the Atlantic Ocean two minutes later. The first ARPA-sponsored lunar mission had failed.

Back in the Soviet Union preparations to launch the first E-1 probe early on August 18 were falling behind. Frustrated by a series of malfunctions on the pad, Korolev finally called off the launch after hearing of the USAF Thor-Able 1 failure. The uncooperative 8K72 rocket was removed from the pad and returned to the MIK assembly building in hopes of making another launch attempt the following month.

Meanwhile in the US, an analysis of the telemetry and hardware recovered by Navy divers showed that a fault in the turbopump in Thor’s MB-3 engine was to blame for the failure. A similar fault had also caused the failure of two earlier Thor launches including the first ARTV flight on April 24, 1958 although the Thor-Able 0 had operated satisfactorily during the two subsequent ARTV launches on July 10 and 14. With the cause of the first Able-1 failure determined, it was decided to replace Thor 129, which had already been erected on the launch pad on August 19 in preparation for a September launch attempt, so that the fault in its MB-3 engine could be corrected. The next launch attempt was pushed back a month with a modified Thor 130 substituted to serve as the booster. For the next launch window in September, Korolev’s team would have the stage to themselves. In the meantime, a new name was officially adopted by the USAF for this series of flights – Pioneer. The first unsuccessful launch attempt was retroactively designated “Pioneer 0” with the next mission scheduled for October to be called “Pioneer 1”.

On September 23, 1958, the Soviet 8K72 B1-3 was back on its pad ready to try for the Moon again. The unproven rocket smoothly lifted off at 12:03:23 Moscow Time (09:03:23 GMT) during its brief launch window and accelerated towards its target. But as the propellant tanks of the core and strap-on boosters emptied, longitudinal resonance vibrations (an effect called “pogo”) appeared. Pogo had been encountered in some earlier flights of the R-7 and Korolev’s engineers thought they had understood and corrected for its cause. The reappearance of this problem would finally doom the flight 93 seconds after launch when the strap-on boosters broke loose. The now free flying collection of uncontrolled rockets with the E-1 No. 1 probe still attached tumbled to the ground and exploded on impact. The Soviet’s first attempt to reach the Moon ended as ingloriously as the American’s. But unlike the American attempt, this failure was kept quiet firmly establishing the Soviet government’s policy of keeping launch failures secret.

The Race Heats Up

Another 8K72, serial number B1-4, was hastily modified by Korolev’s engineers for another clandestine launch attempt the next month. As in August, Korolev would have to race against the Americans who were preparing another Thor-Able to launch a 38.3 kilogram Pioneer probe towards lunar orbit. But unlike the August launch, ARPA was no longer in charge of the American effort. An act of Congress officially established the National Aeronautics and Space Administration (NASA) to run the United States’ civilian space program starting on October 1, 1958. Much to the chagrin of those who wanted the DoD to run the infant American space program, President Dwight Eisenhower transferred most of the DoD’s purely scientific space projects to the new agency including ARPA’s Pioneer program. With ARPA and the USAF relegated to an advisory role, the next Pioneer mission would be the first launch for the fledgling space agency.

With the USAF still officially in charge for the moment, Thor 130 was erected on the pad at LC-17A on September 22, 1958 to begin preparations for what would become the launch of NASA’s first space mission. A static test firing of the Thor without the upper stages and payload attached was successfully conducted on October 1. The second stage, with “USAF” still painted on its side, was mounted on top of the Thor the following day with the solid-propellant third stage added on October 8. The Pioneer 1 spacecraft, which finished the stack as “stage 4”, was identical to its predecessor except for the addition of an ion counter designed by Dr. James Van Allen. This new instrument was similar to those he had flown on earlier Explorer satellites launched by the ABMA team led by Wernher von Braun (see “Explorer 1: America’s First Satellite”).

As before, trajectory requirements allowed the US lunar probe to get off the pad first. After a number of built-in and unplanned holds to attend to issues during the countdown, Thor 130 lifted off on October 11, 1958 at 4:42:13 AM EDT (08:42:13 GMT) – only 13 seconds into its launch window. Unlike the previous attempt, the Thor first stage operated properly this time giving the Able stages their chance. The second stage fired followed by a nominal burn of the X-248 third stage. At first it seemed that the launch was a success and the probe would reach the Moon.

Meanwhile in the Soviet Union, word arrived about the successful launch of Pioneer 1 as Korolev and his team pushed hard to make their launch window during the early local morning of October 12. While Pioneer 1 was the first up, the faster trajectory of Korolev’s E-1 No. 2 probe would allow it to reach the Moon several hours before the American probe giving the Soviet Union another space first. A true race to the Moon like never seen before or since was on. After a night of hectic preparations, the second 8K72 lifted off its launch pad at 02:41:58 Moscow Time (23:41:58 GMT on October 11) to chase after its American competitor. But despite the best efforts of Korolev and his team, the pogo effect that destroyed the first 8K72 launch vehicle reappeared in the new rocket as it climbed towards space. After a flight of 104 seconds, 8K72 B1-4 finally disintegrated under the stress. With this latest failure, future launch attempts to the Moon using the 8K72 were put on hold until the cause of the ongoing problem could be ascertained and a fix implemented.

Fortunately for Korolev and his team, it was soon discovered that Pioneer 1 was not headed for the Moon after all. Initial tracking of the receding Pioneer 1 showed that the spacecraft was travelling slower than required. In the hours following launch, continued tracking made it apparent that the probe was also off course. Analysis of the telemetry received during ascent showed that the Thor autopilot had steered the rocket 2.5° too high and was travelling about 244 meter per second faster than expected at first stage cutoff. Because of the inability of the relatively primitive second stage guidance system to adapt, the amount of loft had increased to 3° with the second stage cutoff prematurely with ten seconds of propellant still left. This resulted in a velocity deficit of about 61 meters per second. A disturbance during separation and ignition of the third stage knocked the ascending rocket 15° further north than desired. At third stage burnout, Pioneer 1 was travelling 152 meters per second shy of its intended 10,731 meter per second final velocity and 5° off course. Even after firing its vernier rockets to gain another 49 meters per second, Pioneer 1 would reach no higher than 113,830 kilometers 21½ hours after launch before arcing back towards the Earth.

While reaching the Moon was out of the question, Pioneer 1 could still use its instruments to investigate this previously unexplored region of space. For the first time since their discovery earlier that year, the full extent of the Van Allen radiation belt was probed. Pioneer 1 found that it extended to 8,000 to 11,000 kilometers above the equator before fading out at an altitude of 15,000 kilometers. The Van Allen belt would not be a barrier to piloted missions passing through on their way to destinations beyond the Earth as some had begun to fear. Since Pioneer 1 travelled so much higher than any previous payload, it was also used in the first communication satellite tests with telemetry being relayed between tracking stations in Hawaii, Cape Canaveral and Manchester, England. It would be two months before the first dedicated communications satellite payload was launched as part of DoD’s Project SCORE (see “Vintage Micro: The Talking Atlas“).

To continue gathering useful data, ground controllers came up with an alternate mission plan. They decided to ignite Pioneer’s TX-8 solid retrorocket motor 28 hours after launch to raise probe’s perigee up to around 32,000 kilometers. Orbiting the Earth about once every 2½ days, Pioneer 1 could observe the outer reaches of Earth’s magnetosphere until its batteries were exhausted. It might also prove possible to use Pioneer’s camera to obtain the first image of the Earth from cislunar space.

While this plan promised to salvage something out of the flight, bad luck would strike again. The launch aim error had left Pioneer 1 spinning at an unintended angle to the Sun. The probe’s simple thermal control system could not adapt to the change and internal temperatures fell to 2° C. When the command to ignite the retrorocket was given, it failed to fire because the cold had affected the command receiver’s battery. Pioneer 1 was now forced to continue in its ballistic path which ended in a fiery reentry over the South Pacific Ocean off the coast of Peru 43 hours and 17 minutes after launch. And since the retrorocket did not fire, Pioneer’s camera failed to activate resulting in no pictures of the Earth as well. Even though Pioneer 1 did not reach the Moon, the record breaking flight still helped America’s flagging morale as preparations were made for the final launch of Project Able-1 .

While Korolev’s efforts to get the Soviet Union to the Moon first got a reprieve with the failure of Pioneer 1, it was only a brief one. The last of the original ARPA Pioneer orbiters was immediately prepared for launch in the hopes of beating the Soviets. Unknown to everyone in the West, this time the American attempt would go unanswered as a commission of Soviet engineers and scientists continued to investigate the cause of the 8K72 launch failures. But just as Korolev and his team were learning from their failures, Korolev’s American counterparts learned from theirs. In order to avoid another premature shutdown of the Thor-Able second stage for the last of the original Pioneer lunar orbiters, the guidance system was outfitted with a Doppler command system that would minimize trajectory errors and ensure a more accurate course to the Moon.

Modifications were also made to the probe itself raising its mass to 39.6 kilograms including 15.6 kilograms of instruments. One of those changes involved the replacement of the original camera supplied by NOTS with an improved 1.4-kilogram unit built by STL. More flexible in operation than its predecessor (and not dependent on the firing of the retrorocket to begin imaging), the new camera would build up one pixel of a 128-by-128 pixel image for each revolution of the probe spinning about twice each second. Like the earlier unit, the scene could then be slowly built up one line at a time over 2½ hours as the probe moved in relation to its target. The image scale was expected to be about 40 kilometers per pixel from a nominal range of 6,400 kilometers. Unlike the earlier camera, the STL-built unit would be capable of taking multiple images with one planned of the receding Earth during its departure, a second at about the time of retrofire of a half illuminated Moon and a last image of a full Moon which would include the unexplored far side.

On November 7, 1958 at 2:30 AM EST (07:30 GMT) the third Thor-Able 1 carrying Pioneer 2 blasted off from LC-17A. While the Thor 129 first stage as well as the modified second stage operated perfectly this time, the X-248 third stage failed to ignite thus dooming the latest NASA Moon probe. With a velocity of only 7,198 meters per second at the time of probe separation, Pioneer 2 reached a peak altitude of 1,550 kilometers before arcing back to Earth 42.4 minutes after launch to burn up over eastern Africa. Its new camera never had an opportunity to operate but if it had, its image of the Earth would have looked similar to the one successfully returned by a similar device on August 14, 1959 carried by the STL-built Explorer 6 satellite. While an image like this of the Earth and, if Pioneer 2 had reached its target, the Moon would have been historic, in retrospect it is doubtful that any features on the lunar surface would have been observed given the low contrast of the features on the lunar far side.

With this last Pioneer orbiter flight, NASA’s lunar hopes turned to the pair of smaller six-kilogram Pioneer flyby probes inherited from von Braun’s group at ABMA which would be ready to launch in December. But the different trajectory requirements of this probe dictated a launch window that opened two days after the next possible Soviet E-1 launch attempt. Fortunately the commission charged with finding the reason for the first two 8K72 launch failures were able to trace the source of the problem. While pogo had been largely eliminated from the two-stage R-7 variants, it was discovered that the addition of the new Blok E third stage raised the rocket’s center of gravity and altered its resonant vibration frequency in such a way to make the problem reappear as the rocket’s propellant tanks emptied. A simple baffle was introduced in the boosters’ oxidizer pipeline to eliminate the effect and Korolev’s team was ready to try for the Moon again. The next round in the race to be first to the Moon would start in December 1958.

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Related Video

Here is an excellent STL-produced video from 1958 about the Pioneer 1 launch entitled Project Able-1 Space Probe: Report No. 2.

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Pioneer 1: “Project Able-1 Space Probe” 1958 Space Technology Laboratories – US Air Force from Jeff Quitney on Vimeo.

Related Reading

“Pioneer 1: NASA’s First Space Mission”, Drew Ex Machina, October 11, 2016 [Post]

“The Largest Launch Vehicles Through History”, Drew Ex Machina, February 19, 2018 [Post]

General References

Brian Harvey, Soviet and Russian Lunar Exploration, Springer-Praxis, 2007

Wesley T. Huntress and Mikhail Ya. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer-Praxis, 2011

Gideon Marcus, “Pioneering Space”, Quest, Vol. 14, No. 2, pp. 52-59, 2007

Gideon Marcus, “Pioneering Space – Part II”, Quest, Vol. 14, No. 3, pp. 18-25, 2007

Ari Shternfeld, Soviet Space Science, Basic Books, 1959

Asif A. Siddiqi, “Before Sputnik: Early Satellite Studies in the Soviet Union 1947-1957 – Part 2”, Spaceflight, pp. 389-392, Vol. 39, No. 11, November 1997

Asif Siddiqi, “First to the Moon”, Journal of the British Interplanetary Society, Vol. 51, No. 6, pp. 231-238, June 1998

Adolph K. Thiel, “The Able Series of Space Probes”, May 20, 1960

Timothy Varfolomeyev, “Soviet Rocketry that Conquered Space Part 2: Space Rockets for Lunar Probes”, Spaceflight, pp. 49-52, Vol. 38, No. 2, February 1996

Timothy Varfolomeyev, “Soviet Rocketry that Conquered Space Part 3: Lunar Launches for Impact and Photography”, Spaceflight, pp. 206-208, Vol. 38, No. 6, June 1996

“1958 NASA/USAF Space Probes (Able-1) Final Report: Volume 1 – Summary”, Space Technology Laboratory, February 18, 1959

“1958 NASA/USAF Space Probes (Able-1) Final Report: Volume 2 – Payload and Experiments”, Space Technology Laboratory, February 18, 1959