Luna 2

• 1. Introduction

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  Luna 2 became the first human-made object to touch another world on the 14th of September 1959. A Soviet spacecraft, launched less than two days earlier, struck the Moon at about 3.3 km/s and ended a chapter of human history in which no artifact of civilization had ever left Earth to land somewhere else. What brought it there, what it carried, and what the world made of the moment are questions worth sitting with.

  The spacecraft had a name before it had its number. Soviet authorities originally called it the Second Soviet Cosmic Rocket. Western journalists nicknamed it Lunik 2. It was, by the internal accounting of the Luna programme, the E-1 No. 7 mission. It had taken six attempts to get here. Four previous spacecraft had failed entirely, never reaching the Moon. Luna 1, the closest the programme had come, missed the Moon by 5965 km. Luna 2 would not miss.

• 2. Six Attempts to the Moon

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  On the 23rd of September 1958, the first unnamed Luna probe exploded on the launch pad. Two more attempts, on the 11th of October and the 4th of December of that year, also failed to reach the Moon. Luna 1 launched on the 2nd of January 1959 and came the closest yet, but it still sailed past, missing by nearly 6000 km.

  One more failure separated Luna 1 and Luna 2: an unnamed probe that failed to launch properly on the 18th of June 1959. The Soviet programme did not publicize these failures. Spacecraft that did not succeed were simply never given names and were not acknowledged publicly.

  Luna 2 itself nearly joined that list of silent failures. The first launch attempt, on the 6th of September 1959, was scrubbed because of a loose electrical connection. A second attempt two days later stalled when ice blocked a pressure sensing line in the core stage's liquid oxygen tank. Engineers broke the ice plug, but the launch could not proceed. By that point the rocket fuel, RP-1, had been sitting in the tanks for nearly four days and risked a chemical breakdown called paraffinization. A third attempt on the 9th of September reached ignition but the engines climbed only to 75% thrust; an electrical switch had failed to open the valves to full throttle. The booster was rolled off the pad entirely and replaced. The mission finally launched on the 12th of September 1959 at 06:39:42 GMT.

• 3. What Luna 2 Carried

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  The probe weighed 156 kg on its own, with a combined mass of 390.2 kg once paired with its launch stage. Its body was spherical with protruding antennas, similar in shape to Luna 1 before it. Inside were five types of scientific instruments: scintillation counters to measure ionizing radiation, Cherenkov radiation detectors for electromagnetic radiation caused by charged particles, a Geiger counter assembly of three STS-5 gas-discharge counters mounted on the outside of an airtight container, ion traps, and a three-component fluxgate magnetometer with a dynamic range reduced to plus or minus 750 gammas to sharpen its precision compared to the Luna 1 instrument.

  The probe's batteries were silver-zinc and mercury-oxide. There were no propulsion systems on Luna 2 itself; once it separated from the rocket's upper stage it was committed to its trajectory.

  The spacecraft also carried pennants. Two sphere-shaped ones were mounted on the probe itself, each surface tiled with 72 pentagonal elements in a pattern that would later be familiar as the design of an association football. At the centre of each sphere sat an explosive charge. Each pentagonal tile was made of titanium alloy. The central regular pentagon bore the State Emblem of the Soviet Union and the Cyrillic letters for USSR. The surrounding five irregular pentagons each carried the inscription USSR SEPTEMBER 1959 in Cyrillic. A third pennant consisted of similar engravings pressed onto aluminium strips attached to the rocket's last stage. Scientists also took unspecified extra precautions to prevent biological contamination of the Moon.

• 4. Journey and Impact

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  Luna 2 left Earth at an initial velocity of 11.2 km/s. After the upper stage detached, the probe traveled on its own, rotating slowly and making one full revolution every 14 minutes. It transmitted signals on three frequencies: 183.6, 19.993, and 39.986 MHz. Those transmissions gave scientists on the ground precise trajectory data, enough to calculate that the probe would hit the Moon around 00:05 on the 14th of September by Moscow Time. That prediction was announced publicly on Radio Moscow.

  On the 13th of September, while still in flight, the spacecraft released a cloud of sodium vapour. The cloud expanded to a diameter of 650 km and was visible to observatories in Alma Ata in Kazakhstan, Byurakan in Armenia, Abastumani and Tbilisi in Georgia, and Stalinabad in Tajikistan. It served a dual purpose: a visible marker of the spacecraft's position, and an experiment in how sodium gas behaves in a vacuum with zero gravity.

  Shortly before impact, the two sphere-shaped pennants detonated as designed, sending their 72 titanium pentagonal shields outward in every direction. Luna 2 hit the Moon at 00:02:24 Moscow Time on the 14th of September 1959, striking at about 0 degrees west and 29.1 degrees north, east of Mare Imbrium near the craters Aristides, Archimedes, and Autolycus. The rocket's final stage struck the surface roughly 30 minutes later, though its precise landing point was never confirmed.

• 5. Bernard Lovell and the Skeptics

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  Bernard Lovell, the astronomer at Jodrell Bank Observatory at the University of Manchester, received a telex from Soviet scientists before the impact. It contained the expected time of impact and the transmission and trajectory details. Soviet scientists sent the message specifically because international observers had claimed that data from Luna 1 was fabricated.

  Lovell began tracking Luna 2 about five hours before it struck the Moon. He recorded its radio transmission. The signal cut off abruptly at the moment of impact. He then played that recording over a phone call to reporters in New York. He proved the signal was genuinely coming from Luna 2 by demonstrating the Doppler shift in its transmissions, which is the measurable change in radio frequency caused by an object moving toward or away from a receiver. American media remained skeptical until Lovell presented that evidence. His confirmation transformed a Soviet announcement into an independently verified fact.

• 6. What the Instruments Found

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  Luna 2's instruments sent data back to Earth approximately once every minute until the probe's final transmission, which came when it was about 55 km from the lunar surface. The probe did not detect any magnetic field around the Moon at or beyond the limits of the magnetometer's sensitivity, set at 2-3 times 10 to the negative 4 Gauss. It also found no radiation belt around the Moon comparable to the Van Allen belts around Earth.

  The ion traps recorded something else: at an altitude of 8000 km, the particle flux increased, which suggested the Moon might have a thin ionosphere. The probe also measured variations in the electron flux and energy spectrum within the Van Allen radiation belt during its passage through that region near Earth. Using the ion traps, Luna 2 made the first direct measurement of solar wind flux from outside the Earth's magnetosphere. All of the scientific data the probe generated was printed out across 14 km of teletype paper. Researchers analysed it and published their findings in the spring of 1960.

• 7. Khrushchev, the CIA, and the Pennant

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  Soviet Premier Nikita Khrushchev was visiting the United States later in September 1959. He gave President Dwight D. Eisenhower a replica of the Luna 2 pennants during that visit, his only trip to the United States. According to Donald William Cox, Americans had been reassuring themselves that although Soviet rockets were larger, American guidance systems were superior. Luna 2's success put that reassurance in doubt. At the time, the closest any American spacecraft had come to the Moon was about 60,000 km, achieved by Pioneer 4.

  During the same period, a Soviet exhibit of economic achievements was touring several countries and included Luna 2 on display. The CIA ran a covert operation to examine it. A team of CIA officers gained unrestricted access to the exhibit for 24 hours. What they found surprised them: the displayed object was a fully operational system comparable to the original spacecraft, not the replica they had expected. The team disassembled it inside its crate, photographed every component, and reassembled it without the Soviets noticing. The CIA report on the operation was classified for decades and declassified only in 2019-28 years after the dissolution of the USSR.

  The replica Khrushchev gave Eisenhower is kept today at the Eisenhower Presidential Library and Museum in Abilene, Kansas. A copy of the spherical pennant is also held at the Kansas Cosmosphere in Hutchinson, Kansas. On the 1st of November 1959, the Soviet Union issued two postage stamps commemorating Luna 2, depicting the trajectory of the mission.