The First Lunar Probes
 
 
Don P. Mitchell
 
Following the Sputnik launches in 1957 and 1958, the Soviet Union's next achievement in space was the exploration of the Moon. In 1959, Luna-1, Luna-2 and Luna-3 were the first spacecrafs to achieve escape velocity, impact the Moon and photograph its far side.
 
Cosmic Rocket
 
The R-7 rocket was augmented with a third stage, making it possible to acheive escape velocity and reach the Moon. New ground facilities were built to deal with guidance, remote control and telemetry for the first deep space mission.
Even as the Sputnik missions were being built, chief designer Sergei Korolev and academic leader Mstislav Keldysh began planning the missions to send probes to the Moon. Under the payload code name of "Object-E", probes were designed to impact the Moon and photograph its far side.
The R-7 had been able to launch sizeable payloads into orbit, which requires acceleration to a speed of 7.9 km/sec. However, to reach escape velocity of 11 km/sec, twice the energy per payload mass was needed. To achieve that, the R-7 was augmented by a third stage, and a more accurate guidance and control system was developed.
 
The Three-Stage Luna Rocket
 
Luna Rocket
 
Block-E
 
Korolev and his associates began discussing concepts of Lunar missions as early as 1956, but in January of 1958, Mstislav Keldysh sent him a letter outlining specific mission goals, to impact the Moon with a probe and to photograph its far side and transmit the images to Earth by television. The two men convinced the authorities, and a government authorization was issued on March 20.
 
To achieve these goals, the power of the R-7 rocket was augmented by a third stage called Block-E. The resulting rocket was code named 8K72. Because it was designed for deep space, it was referred to publically as a Cosmic Rocket (raketa kosmicheskie). Block-E weighted 1.12 tons and carried 7 tons of kerosene fuel and liquid oxygen in a pair of toroidal tanks. The tanks and engine assembly was also used on the Vostok rocket, to launch heavy manned capsules and surveillance satellites. This new rocket would be able to carry 6 tons into low Earth orbit and 1.5 tons to escape velocity.
 
A 5-ton thrust engine, the RD-0105, was derived from the steering engines on the R-7. Although the R-7's main engine was designed by Glushko's firm, Korolev's own people worked with Semyon Kosberg's bureau to augment the R-7 vernier engines with fuel turbopumps and steering jets powered the pump's exhaust.
Block-E was developed by Korolev's chief deputy, Vasily Mishin, at the same time as the two-stage R-9 ballistic missile. Both rockets dealt with the problem of how to start a rocket stage in space. In both cases, the upper stage was attached by an open truss, allowing its engine to start while the 
Block-E with Luna-1 Scientific Pod
first stage was still accelerating. Acceleration kept the propellants settled at the bottom of their tanks and prevented bubbles from being sucked into the engine.
 
In addition to the new rocket stage, the retractable scaffold and gantry system at Baikonur had to be lengthened to permit fueling and preparation of the taller rocket. In Siberia, two new telemetry and tracking facilities were constructed at Tartask and Kolpashevo to monitor the flight of the third stage.
 
Tracking and Telemetry Systems
 
Radio Control System for Rocket Launch
RUP Antenna
The R-7 ICBM could fly with an autonomous inertial guidance system, but its accuracy was only about 10 km around the target. Using a ground-based radio trilateration and guidance system, accuracy was improved to 2 km. This precision would be vital for the launching of space missions, especially to intercept the Moon. The radio control system operated on 3 cm wavelength and was developed by Yevgeny Boguslavsky, at the design bureau RNII KP. It consisted of a pair of RUP stations (radio control points) situated 250 km on either side of the launch pad in Baikonur. Impulses transmitted by the primary station were returned by an onboard transponder and received by the relay station.
 
Using pulse-return time and doppler shift, this system measured radial distance, lateral devation from the nominal trajectory, and velocity. The lateral deflection of the sustainer stage of the R-7 was controlled with an accuracy of 5 minutes of arc, and the engine cut-offs were timed to give a final velocity accurate to 2 meters per second. When Block-E was engaged, its course was stabilized by onboard gyroscopic sensors. Engine cut-off was either timed by an onboard ?V sensor (an integrating accelerometer) or by radio control. More accurate Doppler readings of speed could be obtained from a third RUP behind the launch pad in Tashauz, Turkmenistan, but a new system replaced the multi-point radio control system before this was ever really put to use.
 
The Luna rocket was actually based on the new R-7A, a lighter-weight missile with a 12,000 km range. Along with the new rocket came an improve radio guidance system based on a single RUP using interferometry. This was probably used for the Luna missions, which were launched before the R-7A ICBM itself was tested.
 
 
The First Deep Space Communication System
 
For the Lunar missions, a system was needed for tracking the spacecraft position and velocity at great distances. The R-7 tracking and telemetry systems, were only designed to work down range from launch to a distance of where engine cut-off occurred. For the first three Lunar missions, a telemetry system was designed by Evgeny Boguslavsky, the designer of the RTS telemetry system and radio guidance systems used on the R-7. Commands were sent with a 10 kilowatt transmitter on 102 MHz, from a helical antenna array in Simferopol. Telemetry from Block-E and the Luna scientific pod were received in Baikonur, on 183.6 MHz (9/5 times 102) and on shortwave.
 
Luna-3 video was received on 183.6 MHz, using cooled parametric pre-amplifiers and large phased arrays of quadrupoles, mounted on Wurzburg radar turrets. Stations were located on the southern coast of the Crimea and on the Kamchatka peninsula. A large parabolic receiver was under construction in Simferopol, which would eventually replace the Lunar telemetry stations in Baikonur and Crimea.
 
At some point in the Luna program, a pulse system for ranging was replaced by continuous-wave frequency modulation (CWFM). This used a 0.5 second frequency shift of the subcarrior, comparing the outgoing frequency to the returned signal. This used a narrower bandwidth than radio pulses, and so could tune out more background noise and permit greater amplification. The CWFM radio ranging system had an accuracy of 2 km and was called vektor skorosti (vector velocity). It was operated from the station in the Crimea, perhaps using the same antenna later used for Luna-3 video.
 
The first system used by the ballistic control center, for trajectory calculations and analysis, was the Ural-1 computer. This machine contained 800 vacuum tubes, several thousand germanium diodes and a magnetic-drum memory holding 1024 words of data. Real-time flight control of the rocket was most likely performed by another, special purpose, computer.
 
 
 
The Ural-1 Computer
 
When launched, the R-7 sustainer stage, Block-A, burned for about five minutes. To gain better accuracy of the rocket's velocity, the main engine was cut off early and the final speed was trimmed by burning just the small steering engines. Block-E burned for about seven minutes, and at engine cut-off the stage was about 1500 km above Siberia. From there, it would coast for 34 hours before reaching the Moon.
 
The total payload to escape velocity was about 1.5 tons, which includes the Block-E rocket stage after its fuel was exhausted. The Block-E stages carried a small "scientific pod" that was released after engine shutdown. While we often think of the scientific pod as the spacecraft, both the pod and the rocket stage carried radio and scientific gear and both made the journey to to the Moon.
 
Rzhiga's 20 MHz Antenna
 
Rzhiga's 40 MHz Antenna
 
Rocket telemetry from Block-E was sent with the RTS-8E system on 183.6 MHz. After engine cut-off and deployment of the scientific pod, RTS-8E turned off, and the pod began to send telemetry on the same frequency, using the RTS-12B system. Later, these frequencies were adjusted to be 1.6 MHz different, so both the pod and Block-E could work without interfering. 183.6 MHz telemetry was sent using pulse-time modulation from four short antennas on the top of the pod. They were received at Baikonur on the AFU-U-A-12B antenna system. 120 sensor measurements were repeatedly transmitted at the rate of one per second.
 
As a safety measure, the same telemetry was sent by the Jupter system. After ejection from Block-E, the scientific pods unfurled two steel ribbons to form a V-dipole antenna. These operated on 19.993 MHz (Jupiter-1) or twice that frequency, 39.986 MHz (Jupiter-2, used with Luna-3). Block-E also contained shortwave transmitters operating on various combinations of 19.995, 19.997 and 20.003 MHz on different missions. These signals were sent with pulse-duration modulation, recieved at Baikonur with the AFU-Yu1 directional antenna field. Five rhombic antennas were mounted on wooden poles, aimed to cover a 150 swath of the sky. The 40 MHz Jupiter-2 signal was recieved by a steerable Yagi antenna.
 
Experimental receivers for the Luna telemetry were erected near the Mount Koshka telemetry station, by Vladimir Kotelnikov, Oleg Rzhiga and engineers from the Insitute of Radio Engineering and Electronics. Antennas were dipole and quadrupole Yagi arrays, seen above. The pair of dipole arrays used for 20 MHz was designed to combine the direct signal and the signal reflected off the surface of the water. Systems were tested using the still-active Mayak signal from Sputnik-3.
 
PDM telemetry consisted of a 7-second syncronization tone, followed by a sequence of 120 values from scientific instruments and spacecraft status. Variation in the signal strength was due to the slow tumbling of the scientific pod.
Typical PDM signal (from Luna-2)
 
Pioneer/Able Program
 
Soviet Lunar Stage, Block-E
 
Pioneer-3 Atop Its Rocket Stage
 
Concurrent with Soviet efforts, the United States made eight attempts to send simple probes to the Moon, as part of the Pioneer/Able program. All of these missions failed, but Pioneer-3 got high enough to detect the outer radiation belt in its equatorial region (Sputnik-3 had first detected it at the point where the belt approached the north pole of the Earth). Pioneer-4 was the first American spacecraft to reach escape velocity, on March 3 of 1959, but it missed the Moon by 60,000 km.
 
At that point in time, Soviet rocket technology was considerably more powerful and accurate. Payload capacity to translunar trajectory of the Luna rocket was more than 100 times that of the Juno II missile used for Pioneer 3 and 4.
 
 
Lunar Impact
 
The first phase of Lunar exporation was Program E1, a series of missions to explore deep space and impact the Moon. Satellites had discovered properties of near Earth orbit, most noteably the radiation belts. The E1 probes would measure cosmic radiation, plasma and micrometeorites well beyond the influence of the Earth's magnetic field. They would also measure the distant magnetic field of the Earth and try to detect the Moon's field, if it had one.
 
The Scientific Pod
 
In the schematic diagram, above right, the numbered components are:
 
1 Magnetometer
2 183.6 MHz Antenna
3 Micrometeorite Counter
4 Batteries & Electronics
5 Ventilator Fan
6 Spacecraft Shell
7 Ion Traps
8 Ribbon Antenna for 19.993 MHz
Luna-1 Scientific Pod
 
Schematic
 
Most scientific instrumentation for program E1 was housed in a spherical pod 80 cm in diameter, made from an aluminum magnesium alloy. Two hemispherical sections were joined with bolts and a rubber gasket, then filled with nitrogen under 1.3 atmospheres of pressure. The capsule weighed 170 kilograms, which included silver-zinc and mercury-oxide batteries for power. Like the sputnik-1 capsule, the temperature of the probe was regulated to 20-25C by the object's reflectivity, and a ventilator fan inside distributed heat from the working electronics to the cold outer shell.
 
Internals of Scientific Pod
 
Electronic Gear on Block-E
 
Scientific experiment inside the pod was mounted on a tubular magnesium frame. It included:
1 Flux-Gate Magnetometer
2 Plexiglas Cherenkov Detector
3 2 Micrometeorite Counters
4 4 Ion Traps
5 Sodium-Iodide Scintillation Counter
6 2 Interior Geiger Counters (Luna-1)
 
 7 3 Interior Geiger Counters (Luna-2)
 8 3 Exterior Geiger Counters: 2 copper-clad, 1
        lead-clad (Luna-2)
 9 19.993 MHz Transmitter (Jupiter-1)
10 39.986 MHz Transmitter (Jupiter-2)
11 183.6 MHz Transmitter (RTS-12B)
 
The pod was ejected from Block-E so its sensors, radio and cooling systems would not be affected by the large rocket stage. Block-E followed close behind carrying an additional 220 kg of scientific instrumentation to the Moon. Scientific equipment onboard Block-E included:
 
1 Cherenkov Detector with Plexiglas Detector (Luna-2)
2 Cesium-Iodide Scintillation Counter
3 Sodium-Iodide Scintillation Counter (Luna-2)
4 Sodium Vapor Experiment
5 19.995 & 19.997 MHz Transmitters (Luna-1)
619.997 * 20.003 MHz Transmitters (Luna-2)
7 183.8 MHz Transmitter (RTS-8E)
 
The pod also contained commemorative pennants, to be delivered to the Lunar surface. These included a metal ribbon bearing the date and the name of the USSR, and a pair of stainless steel spheres (7.5 and 12 cm in diameter) made up of pentagonal medals with the Soviet coat of arms. The spheres were filled with liquid and an explosive charge to burst apart on impact and scatter the pennants. However, with a Lunar impact speed of 3.3 km/sec, it is questionable if any part of the spacecraft could survive without being vaporized.
Soviet Pennants for Luna-2
 
Launches of Luna-1 and Luna-2
After less than a year of rapid development, the first launch was attempted on September 23rd, 1958. The first stage of the rocket failed after 87 seconds, due to combustion instability, and a second attempt on October 12th ended in the same way after 104 seconds. The problem was traced to a resonant vibration of 9 to 13 Hz in the fuel lines. After correcting this problem with fuel line dampers, a third launch took place on December 4th. This time the rocket failed after 245 seconds due a defect in the hydrogen peroxide pump of the engine.
Luna Rocket Launch
 
Concerns about the reliability of the RTS-12B telemetry system led to the installation of a redundant radio system called Jupiter-1, designed by Evgeny Gubenko. RTS-12B sent 120 measurements in a two-minute cycle using pulse-time modulation (PTM). Jupiter sent the same information as RTS-12B, on 19.993 MHz using pulse-duration modulation (PDM). An extensible ribbon antenna was added to the scientific pod, on the opposite end from the magnetometer mast. Jupiter was first used on the third Luna launch attempt.
 
At 16:41:21 GMT on January 2 1959, a launch was almost completely successful and the "First Soviet Cosmic Rocket" became the first spacecraft to achieve escape velocity. A few years later, the mission was retroactively referred to as "Luna-1". The Luna-1 rocket should have been able to hit a target on the Moon within 100-200 km, but an error in the ground-based guidance system caused Block-E to burn a few seconds too long, and it missed the Moon by 6000 km after 34 hours of flight and entered into a heliocentric orbit. The trajectory error was caused by a 2-degree error in presetting the R-7 radio guidance system. Radio communication was maintained for 62 hours, to a distance of 597,000 km. The RTS-12B telemetry system had failed, but the 183.6 MHz ranging system still
functioned, and scientific telemetry was sent by the Jupiter-1 shortwave system.
 
A fifth launch attempt made on June 18 failed.
 
At 06:39:42 GMT on September 12, the Second Cosmic Rocket was successfully launched. Engine cut-off occured at 6:51:45, at which point it was on an escape trajectory that would intersect the Moon. Based on results from Luna-1, some changes and additions to scientific instrumenation were made. Luna-2 carried out its mission successfully and impacted the Moon near the region of Palus Putredinus at about 30 N, 0W. Impact of the scientific pod occured at 21:02:24 GMT on September 13, followed by the impact of Block-E about 30 minutes later.
The Trajectory of Luna-2
Tracking the Impact of Luna-2
 
Interferometer Antenna
 
Another view
 
Boguslavsky's long-distance tracking system on Mount Koshka measured the range and radial velocity of the scientific pod. Nearby, radio astronomers from the Lebedev Institute of Physics erected two parabolic antennas to measure the probe's angle of direction by radio interferometry. The antennas had an aperture of about 200 square meters and were calibrated against several known sources, such as the radio galaxy in Cygnus A. The distance between the focal points was thus determined to great accuracy (175.896 meters), before the interferometer was aimed at the 183.6 MHz signal from the Luna-2 scientific pod.
 
As the pod's angle crossed the lobes of constructive interference between the antennas, its signal was amplified, then diminished as it passed through a zone of destructive interference. Each peak represented a change in angle of 31.9 arc minutes. The moment of signal loss was noted at lobe 53.43, giving an angular measurement accurate to about one arc minute.
 
Interferometer Signal from Luna-2
 
The position of Luna-2's impact was estimated from several measurements. In England, the Jodrell Bank Radio Observatory had the world's largest steerable parabolic antenna at that time, and the Russians sent them tracking and frequency information. From the probe's acceleration, they were able to calculate that it struck somewhere within 7 arc minutes of the center of the Moon's face.
 
The rectangular region indicated above represents the impact calculated from the rocket's initial course, as measured by the radio guidance system. It demonstrates a remarkably accurate trajectory, for that time. The radio interferometry system measured only one angular dimension, placing the impact point within one arc minute of a line.
 
Locating the Impact of Luna-2 on the Moon's Face
 
The estimated time and location of the impact was announced ahead of time, and so a number of astronomers looked for the impact by telescope. With a final speed of 3 km/sec, the scientific pod had enough kinetic energy to generate about 300,000 calories, raising its temperature to as high as 4500 K and ejecting dust. It is a matter of some debate whether this could have been observed from Earth. In all, seven sightings were published, but many have been discounted.
 
The English astronomer Patrick Moore, using a 12.5 inch relfector, observed a pinpoint of light at about 21:02:23 near the schneckenberg mountains, 11.2 N 4.97E. This flash was observed at the same time and spot by another English astronomer, H. Percy Wilkins, using a 15 inch reflector. Wilkins also reported seeing a small dark ring following the flash. At the Konkoly Observatory in Hungary, a dark expanding dust cloud was observed at the moment of impact, at the coordinates 25.7 N 4.97 E.
 
Scientific Experiments and Results
 
Sh.Sh. Dolginov designed the magnetometer on Sputnik-3, and on the Luna scientfic pods he installed a three-component metal core flux magnetometer. The device was located on the end of a long spindle, removing it from the influence of the pod's electronics. On Luna-2, the sensitivity of the device was increased by 4, but it still did not measure a Lunar magnetic field. This was a noteable discovery, indicating that if the Moon had a field it must be less than 1/10,000 times as strong as the Earth's.
 
Cherenkov Counter
 
Luna-2 Scientific Pod
 
NaI Scintillation Counter
 
The Luna missions were one of the first opportunities to measure cosmic radiation in deep space, beyond the influence of the Earth's radiation belts. Some of the instrumentation was similar to that used on Sputnik-3. Sputnik-3 had discovered belts of radiation near the north and south pole of the Earth, and the American Pioneer-3 probe demonstrated that this was part of a large and much more powerful outer belt. Luna-1 was the next spacecraft to pass through this region.
Cherenkov counters measure a flash of light caused by relativistic charged particles traveling through a block of plexiglas. Lidiya Kurnasova placed a counter inside the pod and (on Luna-2) one in the Block-E stage. The signal is proportional to charge (Z) squared, so it is a particularly good way to measure the rare heavy-nuclei component of cosmic rays. On the Luna-2 mission, a total of 30,000 counts of Z ? 2, 3,000 counts of Z ? 5 and 100 particles with Z ? 15 were detected.
 
Sergey Vernov and his colleagues placed a variety of scintillation counters and gas discharge (Geiger) tubes in the scientific pods and on Block-E. After the experience of Luna-1, he added three gas discharge detectors shielded with copper or lead, to take measurements in the intense outer radiation belt. These can be seen mounted outside the Luna-2 pod, on the base of the magnetometer spindle. Radiation measurements showed a constant level beyond the Earth's magnetosphere, and no evidence that the Moon had a radiation belt -- further evidence that it lacked a magnetic field.
Radiation Counts from Luna-2
 
Block-E on Luna-1 and Luna-2 carried an experiment to vaporize sodium in space. Four kilograms of the metal was boiled with thermite, and the resulting cloud fluoresced brightly enough to be observed from Earth-based telescopes. This was done to get a precise optical trilateration of the position of the spacecraft, and also to observe the effects of diffusion of vapor in the extremely rarified environment beyond Earth orbit.
 
Sodium Vapor Released by Luna-2
 
The thermite evaporator was tested on September 19, 1958 at an altitude of 430 km, using an R-5A sounding rocket. On January 3, 1959 at 00:58 GMT, the experiment operated at a distance of 119,000 km; however, observation of this was poor, due to a large error in the program timer. On September 12 at 18:42:42, the sodium vaporizer was activated at 152,000 km, and the cloud was visible for about 4 minutes at the Almaa-Ata observatory and from three Tu-4 bombers with telescopes installed, to observe the sodium cloud from an altitude of 10 km.
 
The experiment was carried out by Russian astrophysicists Vladimir Kurt and Iosif Shklovsky. They were able to calculate the pressure of the trace of atmosphere at 430 km from the diffusion pattern, which formed a giant orange glow 10-20 degrees across. At more than 100,000 km, the mean free path of a sodium atom was too long to be scattered by interplanetary matter.
 
Micrometeorite Counter
 
Ion Trap
 
The scientific pods had two piezoelectric micrometeorite counters, built by Tatiana Nazarova. The total area of the detectors was 0.2 square meters. 0.002 impacts per square meter per second was observed in deep space. These were objects of extremely small mass (much less than a millionth of a gram) traveling at extremely high velocity (15 to 40 km/sec).
 
Konstantin Gringauz installed four ion traps on the outside of the pods. These measured interplanetary plasma. As low-energy ions drifted into the region between two charge screens, they would be attracted to them by electrostatic force, creating a small flow of current. On Sputnik-3, he installed two spherical traps that detected plasma from all directions; however, on the Luna missions, the traps were hemispherical.
 
The Solar Wind, An Ion Trap Signal from Tumbling Luna Pod
 
Because the ion traps were hemispherical, they measured the flow of plasma coming from one direction. On Luna-1, Gringauz observed a periodic fluxuation in signal as the scientific pod slowly tumbled in space. This appeared to be the result of a flow of plasma in one direction -- what we now call the Solar Wind. This was probably the most important scientfic discovery of program E1.
 
Before publishing this result, he made a small change on Luna-2. The hemispheres of the pod were offset by 90, so the four ion traps would be in a tetrahedral arrangement instead of co-planar, as can be seen in images of the Luna-1 and Luna-2 scientific pods above (as an aside, diagrams of early pod design show all four traps mounted on one hemisphere). Again, once the spacecraft was outside the Earth's magnetosphere, a constant flow of plasma was discovered in deep space. This flow of plasma was called the "Solar wind", predicted by some theoreticians, but was not widely accepted until these observations were announced.
 
The Hidden Side of the Moon
 
Locked by tidal forces, the Moon keeps one face toward Earth as it orbits, and its far side was never seen by man. Program E2 was the next phase of Soviet Lunar exploration, proposed by Keldysh in January of 1958, it would photograph the far side of the Moon and transmit the images by television to Earth.
 
The Automatic Interplanetary Station
 
In place of the E1 scientific pod, the E2 missions carried an "automatic interplanetary station" designed by Gleb Maximov. The probe was made from an aluminum alloy, cylindrical with hemispherical end caps. Weighing 278.5 kg, it was 130 cm long and 95 cm in diameter, with a wide section 120 cm in diameter. The hemispherical end caps are similar to the two halves of the E1 pod, with a noteable addition of a camera window on one end. Shutters protected the window glass from micrometeorite etching.
The E2A Automatic Interplanetary Station (Luna-3)
 
Like the E1 pods, the probe was filled with nitrogen at 1.5 atm of pressure and had a ventilation fan to circulate the gas, carrying heat from equipment to the outer wall. In addition, a motor on the outside of the probe could slide shutters open or closed, to change the exposure of the wall to the cold of space. This system was designed to maintain an internal temperature of 25 C.
 
Power was supplied by rechargable silver-zinc batteries, supplying 26 volts with a capacity of 6 amp-hours. Power usage varied. The 3-axis orientation system, for example, consumed 60 watts during its operation. Because of the long mission duration, the batteries were recharged by solar cells, installed by Nikolai Lidorenko. He had placed experimental solar cells on Sputnik-3, and like the American Vanguard satellite, they powered a radio beacon. However, Luna-3 was the first spacecraft with systems fully powered by solar cells.
 
Sensors and Camera Window
 
Equipment Framework
 
Many of the E1 experiments were included on E2A, except for the magnetometer. The probe contained a Cherenkov detector, a NaI scintillation counter, three gas-discharge counters (some mounted externally), and four ion traps. Four micrometeorite counters were installed, smaller than the ones on E1 and having a total area of 0.1 square meters. Diagrams show a mass spectrometer mounted on the outside of the spacecraft, but it may have malfunctioned, since there are no results published from it. It was probably intended to test for any trace of a rarified Lunar atmosphere. In addition, Block-E contained 156.5 kg of scientific equipment.
 
The probe sent data on two frequencies, 183.6 and 39.986 MHz, using the quadrupole antenna and a V-dipole ribbon antennas like to those on the E1 pods. The launched probe was designated E2A, because it had a new telemetry system, designed by Evgeny Boguslavsky at the Institute of Space Device Engineering (RNII KP). That system replaced the original E2 radio system, built by the Moscow Energy Institute.
 
The Phototelevision System
 
"Yenisey-2" Phototelevision System
 
AFA-E1 Optical Component
 
To photograph the Moon, a phototelevision unit was developed at the Leningrad Scientific Research Institute of Television (NII-380), in an effort led by Petr Bratslavets. Work began in April 1958 on a system called Yenisey, designed to take photographs on film, automatically develop it, and then scan the images to generate a television signal. The flown camera was an improved version, Yenisey-2, which had two speeds of television scanning.
 
The dual-objective optical component of the camera, code named AFA-E1, was build at the Krasnogorsk Mechanical Plant (KMZ), makers of cameras (both civilian and aerial reconnaissance), telescopes and other optical devices. It took two pictures simultaneously through a 200 mm lens with f/5.6 aperture and a 500 mm lens with f/9.5 aperture. To bracket exposure, the shutter speed cycled though 1/200, 1/400, 1/600 and 1/800 seconds.
 
Diagram of Phototelevision System
 
Petr Bratslavets
 
After photography was complete, the film would be developed and fixed in a one-step chemical process. The film slid through rubber seals to enter and exit the chamber filled with the viscous reagent mixture. It was then dried and stored on a take-up reel. 40 frames of film were stored in the lead-lined magazine, each containing pre-exposed reference marks and photometric wedges for calibration purposes. These were preceded by a zebra-pattern (Shtrichovaya Mira) resolution chart and a standard 0249 television test chart. Following the 40 frames was a photograph of the Moon taken by telescope, the 0249 chart, and pre-developed copies of the 0249 and the zebra test charts.
 
Once developed, the pictures could be scanned and transmitted repeated, upon radio command. During video transmission, a scanning spot of light from a model 8LK2B oscilloscope CRT was focused on the film, and the image was read by an FEU-15 photomultiplier tube. Images were scanned at about 1500 lines/frame at a rate of 0.8 lines/sec, or in a fast mode of 50 lines per second. The film was moved slowly and continuously during the scanning process. Video was sent on the 183.6 MHz carrier using 3 watts of power. The 400 Hz video signal was modulated by FM on a 25 kHz subcarrier. This gave an equivalent resolution of 1000 pixels per scan line. About 30 minutes were required to scan one frame.
 
The Orientation System
 
One of the most novel technologies in the E2 probe was the orientation control system, needed to aim its camera at the Moon. To solve this problem, Boris Raushenbakh and a team of engineers developed the first successful 3-axis stabilization system, called Chaike ("Seagull").
The "Chaike" Orientation Control System
 
Wide-angle photocells measured the direction of the Sun, 4 around the camera window (S) and four on the aft (B). Three gyroscopes (d) measured angular velocity, and a narrow-angle Moonlight sensor (m) looked out through the window with five photocells. These fed into a special purpose computer built from relays, which in turn controlled 8 micro jets. Four jets aimed perpendicular to the central axis (Z) of the probe induced yaw and pitch. Two pairs of jets aimed at a tangent induced clockwise or counterclockwise roll. These could operate continuously, or for finer control, they could emit 1/10 second pulses. The jets were powered by a resevoir of nitrogen under 150 atm of pressure, reduced to 4 atm by a regulator (g).
 
Sensors of Orientation System
 
Micro Jets and a Solar Sensor
 
During most of its mission, the probe would tumble slowly, initially with a period of 165 seconds. Before photography of the Moon, the orientation system would halt this motion, using feedback from the three angular-velocity sensors. All eight jets are needed to reduce rotation,= about all three axes to less than 0.15 deg/sec, which would take about 10 minutes.
 
Next, the aft end of the probe must be pointed approximately toward the Sun, with a precision of about 5. Only the four lateral jets, controlling yaw and pitch, are used for this operation, . In the plane perpendicular to the X axis, are four Solar sensors (two S and two B) and two jets. Based on sensor feedback, the jets act to maximize the S signals from the aft sensors and minimize the B signals. The same operation is performed independantly on the plane of the Y axis with the orthogonal set of four Solar sensors and two jets. Two of the gyroscopic rotation sensors (X and Y axes) are also employed to dampen motion.
 
Given the launch date and trajectory, this would place the Moon within the 60 field of view of the Moonlight sensor (and the Earth was guaranteed to be well outside the view). Using the five-component sensor and the lateral jets, the camera was aimed at the Moon with a precision of 0.5, a process that took about 30 minutes. After photography was complete, a small rotation (180 second period) was imparted to the craft before the orientation system shut down, so it would be heated evenly by the Sun during the rest of the mission.
 
The gyroscopic angular-velocity sensors played a key role during these orientation maneuvers. In the absence of air friction, a spacecraft could oscillate forever, overshooting and correcting its aim. Raushenbakhs system simulated the effect of friction by dampening the microjet impulses in proportion to angular velocity.
 
Planning And Executing The Trajectory
 
The Strela-1 Computer
The trajectory of the E2 probe would be the most complex spacecraft maneuver performed up to then. To photograph the Moon from a distance of 40,000 to 100,000 km and return near the Earth for television transmission, the probe had to be launched on an orbit extending beyond the distance of the Moon. This in itself was a delicate operation, since the velocity after Block-E burn would have to be just 60-90 meters/sec below escape velocity. Soviet rockets and their tracking and guidance systems were designed to launch northward, but an orbit that traveled to the Moon from the north would return from the south, out of radio range of the Soviet Union's territory.
 
The only solution was a gravity-assist maneuver, using the Moon to deflect the probe back in an orbit that returned from the north. The rocket would have to be aimed to pass near the Moon's south pole, coming within a few thousand kilometers of its surface. Dmitri Okhotsimsky oversaw this work, using the new Strela-1 computer at the Steklov Institute of Mathematics.
 
Families of trajectories were calculated, simulating the gravitation attraction of the Earth, Moon and Sun. Considerations included launch energy, percentage of Lunar far side visible during photography and radio visibility from the USSR during the return flight and television transmissions. The study advised two radio reception points at the far eastern and western extremes of Soviet territory. Two photography times were considered: before closest approach, or afterwards while flying away from the Moon. Photographing the Earth was also considered but rejected.
 
The third Soviet cosmic rocket was launched on October 4, 1959 at 00:43:39.7 GMT. A few years later, it would retroactively become known as "Luna-3". October 4 was the second anniversary of Sputnik-1, and only two days before an optimum launch date calculated by Okhotsimsky. The probe reached its closest approach to the Moon (7940 km from center) at 14:16 GMT on October 6. At 03:30 October 7, at a distance of 65,200 km from the Moon, the program timing unit
Luna-3 Trajectory
activated the  hototelevision system. Photography lasted 40minutes, ending at a distance of 68,400 km. At the midway point, the spacecraft position was ?=117.4, ?=17.1, ?=66,800 km in selenographic coordinates.
 
The automatic chemical development of the film was then performed in about 15 minutes, completing the automatic cycle of the camera system. 17 images were acquired and relayed to Earth, although it is possible that 29 photographs were actually taken. 13 images of the Moon are known to exist, and several test patterns were probably also received.
 
Receiving The Images
 
Video telemetry was received by two special radio stations, one at the Mount Kashka station in the Crimea and one at the telemetry station in Yelizovo on the Kamchatka peninsula. 8 hours was required to transmit the images, but the spacecraft's transmitter was operated for only one hour at a time, followed by two hours in standby mode, for solar recharging of batteries. Thus, a total of 25 hours was needed to download the entire set of images. Commands sent to the spacecraft initiated and controlled the film scanning and video transmission.
 
Yenisey-II Receiver
 
Skiatron Image (simulated)
 
Two specialized video recording devices were built, Yenisey-I designed for recording of the video in fast mode (50 lines/sec) and Yenisey-II for slow mode (0.8 lines/sec). One of each device was installed in Simeiz and Yelizovo. The incoming video was recorded on several media. The FM video signal was recorded on magnetic tape, and images were stored on 35 mm film with a flying spot CRT. An electrochemical paper image was printed and a skiatron image storage tube was written, for immediate viewing. The Skiatron was also photographed for additional archiving of the valuable images.
 
A skiatron tube records images by creating f-center dislocations in a crystalline screen, with an electron beam. The back-lit translucent screen becomes dark purple where exposed, and the image can be erased by heat. A simulation of the result is shown above.
 
Frame 28 (500 mm lens)
 
Frame 29 (200 mm)
 
The first attempted telemetry session took place when the probe was at a distance of 470,000 km, about 10 hours after photography, and the results were extremely noisy. The best images were obtained when the probe was about 40,000 km from Earth, on the night of October 18. The photography had been timed so the Moon would appear fully illuminated from the vantage point of the probe, but this also meant that the contrast of the Lunar terrain was somewhat poor. Seen above are examples of images taken by the 500mm and 200mm lenses.
 
Keldysh enlisted the help of British radio astronomer Bernard Lovell, who managed the massive radio telescope at Jodrell Bank. Lovell made some recordings of Luna-3 video, which he shared with the American Jet Propulsion Lab. They have not been seen, but are reported to only show a television test pattern. Sven Grahn has written an excellent history of the work at Jodrell Bank here and a history of the Luna-3 telemetry here.
 
Oct 27, 1959
 
1961
 
1967
 
The collection of images from Simeiz and Yelizovo, were sent to the Sternberg Astronomical institute, where Yuri Lipsky and his associates analyzed them extensively. Copies were also sent to the Pulkovo Observatory and the Gorky Observatory in Kharkov.
 
The first results were published in Pravda on October 27, 1959, carefully reconstructed from the film recordings. Lipsky's team used equipment developed to create better images from the magnetic tape recordings of the video signal, and these were published in 1961 in Atlas Obratnoy Storony Luny. In 1967, a second volume of his atlas was published, with the new Zond-3 images, the second view of the Lunar far side. This also included an improved image made from the Luna-3 magnetic tape.
 
The outstanding geological feature was the lack of large mare basins on the far side of the Moon. Teams at several institutes studied the photographs carefully to catalog and name details. The left crescent of Luna-3's view covers the front of the Moon, and about 70 percent of the far side of the Moon appeared on the right. The dark crator with the central peak in the south was named Tsiolkovsky and the large dark spot to the north Mare Muscoviense (Moscow Sea). Other craters were named after famous Russian scientists, such as Mendeleev, Lomonosov and even the atomic bomb scientist Kurchatov. Images from later spacecraft revealed a few mistakes, such as the Soviet Mountains, where turned out to be impact rays.
 
After Luna-3, the far side of the Moon would not be seen again until Zond-3, in 1965. Complete coverage of the far side by photography was not complete until the American Lunar Orbiter 5, in August of 1967.
 
Pulkovo Observatory's Map
 
 
Two types of test patterns were included on the Luna-3 film, a standard Soviet television chart and a type of zebra-stripe resolution chart called Shtrichovaya Mira. These are not actual images from Luna-3, they just illustrate what was imprinted on the film.
 
Shtrichovaya Mira
 
Television Test Card 0249
 
 
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