Luna 4
Soviet lunar soft-lander that missed the Moon in 1963.
Luna 4, also known as Lunik 4, was a Soviet spacecraft of the Ye-6 series launched in 1963 with the objective of achieving the first soft landing on the Moon. Although it failed to perform a course correction and missed the Moon, the mission marked a transitional phase in the Space Race that eventually led to the successful Luna 9 landing in 1966.
Quick Facts
- Operator
- Soviet space program
- Satcat
- 566
- Mission duration
- 13 days (launch to last contact)
- Spacecraft
- Ye-6 No.4
- Manufacturer
- OKB-1
- Launch mass
- 1,422 kg / 3,135 lb
- Launched
- April 2, 1963, 08:04:00
- Launch rocket
- Molniya-L 8K78/E6
Facts from the source article.
Background
Following the Luna 3 mission, which returned the first images of the lunar far side, the Soviet Union sought to investigate the lunar surface and its suitability for landing and construction. On 10 December 1959, Premier Nikita Khrushchev signed a resolution for the creation of a lunar soft lander with scientific instruments and a television. The task was assigned to a group led by Nikolay Beresnev within Mikhail Tikhonravov's department at OKB-1, under Gleb Maksimov. Sergei Korolev initially led the project before handing it to Beresnev; by 1963, Boris Chertok had de facto management. The working designation was Ye-6. The spacecraft's mass exceeded the capacity of the three-stage Luna rocket, so the 8K78 booster was used, allowing a parking orbit. However, of the first ten 8K78 launches, only two succeeded. The team estimated a 10% chance of success.
Spacecraft
The Ye-6 spacecraft comprised three cylindrical modules, with a height of 2.7 m and a launch mass of 1422 kg. The first module was the Isayev rocket module, containing the main engine for mid-course correction and descent, four attitude control thrusters, and two cruise modules. The main engine used hypergolic propellant (nitric acid and amine) producing about 45,000 N of thrust; each thruster produced 245 N. A 5 m boom would deploy from the bottom to trigger the landing sequence. The second module was a pressurized compartment holding propellant, oxygen, communication equipment, an altimeter, and the I-100 control system. Luna 4 carried an astronavigation system (SAN) derived from aircraft systems. The I-100 package, weighing 80 kg, also controlled aspects of the Molniya rocket's third and fourth stages, a weight-saving measure prone to failures. The third module was a 58 cm diameter spherical lander protected by two hemispherical airbags. The 105 kg sphere contained communications, batteries, thermal control, a timer, and science experiments. Four petals would open on landing, deploying four whip antennas and a camera turret. Batteries were designed for 5 hours of operation over about 4 days. The scientific payload included an imaging system and an SBM-10 radiation detector, a gas-discharge counter 50 mm long and 10 mm in diameter, heavily shielded on one side, with continuous telemetry of radiation counts.
Mission
After development delays, the first flight Ye-6 was built in December 1962. Two earlier launches in January and February 1963 failed. Luna 4 launched on a Molniya-L at 08:16:37 UTC on April 2, 1963, from Site 1/5 at Baikonur, tracked from Simferopol. After reaching a parking orbit of 167 by 182 km, the upper stage restarted to send Luna 4 onto a translunar trajectory. The initial trajectory was correct, but a failure of the Yupiter astronavigation system, likely due to thermal control problems, prevented proper orientation for a midcourse correction. Consequently, Luna 4 missed the Moon by about 8400 km at 13:25 UT on April 5, 1963, entering a barycentric 90000 km × 700000 km Earth orbit. Coverage outside the USSR was front-page news, but TASS released scant details, irritating Boris Chertok. Western scientists deduced the mission was a soft-lander attempt based on the 3.5-day flight duration and larger payload. Radio Moscow's silence and the cancellation of the television program 'Hitting the Moon' on April 5, replaced by a poetry program and piano interlude, provided further evidence. TASS reports were brief, and the last mention in Pravda was a short reference on April 7.
Results and status
Luna 4 transmitted at 183.6 MHz until 15 April. French and Italian astronomers reported receiving pictures of the Moon taken by the probe. A 2.6 m telescope in Russia photographed Luna 4 as a 14th magnitude object early in its flight. Although it did not land, the spacecraft returned data on the radiation environment in cislunar space, showing variations in radiation flux over time comparable to previous missions but with smoother transitions. Because Luna 4 launched during the least active part of the solar 11-year cycle, the gentler variations were conjectured to be caused by changes in local magnetic field effects. Luna 4 also discovered that Earth's geomagnetic tail extended at least as far as lunar orbit. Its path appears to have been perturbed, and it now orbits the Sun.
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