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Luna 4



Luna 4 (Ye-6 no.4) was the USSR's first successful spacecraft of their "second generation" lunar program. The spacecraft, also referred to as an automatic interplanetary station, launched on a Molniya 8K78 on 2 April 1963 at 08:04:00 UT (A launch time of 08:16:37 UT has also been reported) Rather than being sent on a straight trajectory toward the Moon, the spacecraft was placed first in a 167 x 182 km Earth orbit and then was rocketed in a curving path towards the Moon. Luna 4 achieved the desired initial trajectory but during trans-lunar coast the Yupiter astronavigation system failed (most likely due to thermal control problems) and the spacecraft could not be oriented properly for the planned midcourse correction burn. Communications were maintained, but Luna 4 missed the Moon by about 8400 km (sources give reports of 8336.2, 8451, and 8500 km) at 13:25 UT on 5 April 1963 and entered a 89 250 x 694 000 km equatorial Earth orbit. The spacecraft transmitted at 183.6 MHz at least until 7 April. The orbit is believed to have been later perturbed into a heliocentric orbit.

Luna 4 had a mass of 1422 kg and carried an imaging system and radiation detector. The structure was built by design bureau OKB-1 based on the Ye-6 satellite body. The intended mission of the probe was never revealed, it was announced it would travel to "the vicinity of the Moon". It was speculated, and has since been confirmed, that the probe was designed to perform a soft landing on the Moon based on the trajectory and on the later attempted landings of the Luna 5 and 6 spacecraft, as well as the advances made over the 3 years since the successful Luna 3 flyby. (And the fact that a lecture program entitled "Hitting the Moon", scheduled to be broadcast on Radio Moscow at 7:45 p.m. the evening of April 5, was cancelled.)

Spacecraft and Subsystems

The spacecraft was based on the Soviet Ye-6 design, which consisted of a stack of three cylindrical modules. The first module was the Isayev rocket module, which held the main engine, used for midcourse correction and the descent to landing, four thrusters for attitude control, and two cruise modules. The main engine propellant was hypergolic nitric acid and amine, and could produce a thrust of about 45,000 N. The four thrusters were mounted on outriggers and could produce 245 N each. A 5-meter boom would be deployed from the bottom of the spacecraft, used to trigger the final landing sequence. The second module was a hermetically sealed pressurized compartment that contained communication, attitude orientation, an altimeter, and the I-100 control system. It also held the propellant and oxygen.

The third module was the lunar lander, a 58 cm diameter sphere protected by two hemispherical airbags. The 105 kg sphere had a hermetically sealed compartment that held communications apparatus, batteries, thermal control systems, a timer, and the science experiments. The top of the sphere had four petals, which would open up on landing, allowing deployment of four 75 cm whip antennas and the lander camera turret. Control of the lander was done by the timing device onboard or by communication from Earth. The batteries were designed to operate for a total of 5 hours over about 4 days. The scientific payload contained an imaging system and an SBM-10 radiation detector. The three sections had a height of 2.7 meters and a launch mass of 1422 kg.

The mission plan was to initialize the landing sequence at an altitude of about 8300 km. At 70 - 75 km altitude the cruise modules would be jettisoned, the main engine would start, the radar altimeter would be activated, and the lander airbags would inflate. At 250 to 265 meters altitude the main engine would shut off and the four thrusters would ignite. The 5 meter boom would touch the surface first, causing the ejection of the lander, which would hit the surface, cushioned by the airbags, at about 15 m/s. The airbags would deflate, the petals would open, causing the sphere to be oriented correctly, and the antennas and instruments could be deployed.

Alternate Names

  • 00566
  • Luna4
  • Lunik 4
  • Ye-6 no.4

Facts in Brief

Launch Date: 1963-04-02
Launch Vehicle: Modified SS-6 (Sapwood) with 2nd Generation Upper Stage + Escape Stage
Launch Site: Tyuratam (Baikonur Cosmodrome), U.S.S.R
Mass: 1422 kg

Funding Agency

  • Unknown (U.S.S.R)


  • Planetary Science
  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail

Selected References

  • Kolcum, E. H., Lunik 4 believed to have failed in mission, Aviation Week Space Technol., 78, No. 15, Apr. 1963.
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