Venera 3 Is the First Spacecraft to Impact Another Planet

Date November 16, 1965-March 1, 1966

The Soviet planetary probe, Venera 3, was the first human-made object to impact the surface of another planet.

Locale Venus

Key Figures

• G. N. Babakin (1914-1971), chief designer of interplanetary spacecraft
• A. M. Isayev (1908-1971), chief designer of the spacecraft propulsion system
• Sergei Korolev (1907-1966), chief designer of the Soviet space program, 1957-1966
• Vasily P. Mishin (1917-2001), chief designer of the Soviet space program, 1966-1974

Summary of Event

The Soviet Venus probe, Venera 3, was launched on November 12, 1965, by a three-stage A-2e booster from the Baikonur Cosmodrome, near Tyuratam (now in Kazakhstan). The chief designers were G. N. Babakin, A. M. Isayev, Sergei Korolev, and Vasily P. Mishin. The probe’s 43-meter-tall, 509,840-kilogram thrust booster placed Venera 3 into a temporary Earth parking orbit. Before completing its first revolution of Earth, the craft’s “escape stage” reignited and boosted Venera 3 into a heliocentric transfer orbit, which would reach the planet Venus after a flight of 280 million kilometers over 105 days.

The design of the 960-kilogram Venera 3 was based upon a standardized spacecraft bus developed by Soviet engineers for all Soviet unpiloted lunar and planetary spacecraft from the mid-1960’s through the early 1970’s. The overall length of Venera 3 was 3.5 meters. The core of the probe consisted of a 1-meter-diameter pressurized cylindrical compartment containing electronics, batteries, and command and communications equipment. Solar panels mounted on both sides of the spacecraft recharged Venera 3’s batteries. Excess heat generated by the probe’s electronics was carried by fluid circulation to a hemispherical radiator mounted at the end of each solar panel. A 90-centimeter-diameter planetary landing capsule was mounted at one end of the spacecraft bus. At the opposite end was a KDU-414 single-chamber 1.96-kilonewton-thrust course correction engine. Venera 3 was stabilized by nitrogen gas jets controlled by a system that used the Sun and the star Canopus for reference. Long-range communication was maintained through a 2-meter-diameter wire mesh dish high-gain antenna mounted on the side of the spacecraft.

The primary task of the spacecraft’s orientation system was to keep the solar panels aimed at the Sun by positioning the entire spacecraft in an attitude required to illuminate the panels. For this reason, the spacecraft’s attitude was changed to aim the high-gain antenna toward Earth only during scheduled periods of communication with the Soviet deep space tracking antenna in the Crimea. To aim the antenna at Earth, the spacecraft was rolled around the axis of the sun-seeking sensor until the earth-seeking sensor pointed the center of the antenna toward Earth. Another sensor used the star Canopus to orient the spacecraft for firings of the course correction rocket.

Navigation over the extreme distances between Earth and Venus were complicated by the fact that for every 0.3-meter error in the booster rocket’s final velocity, the probe would miss Venus by an additional 9,600 kilometers. The initial trajectory of the Venera 3 probe would have resulted in a 60,550-kilometer miss of the planet. A 21.66-meter-per-second course correction velocity change was accomplished on December 26, when the spacecraft was slightly more than 10 million kilometers from Earth. The speed and distance of Venera 3 was determined by measuring the Doppler shift in the probe’s radio signals.

To prepare for the course correction maneuver, Soviet space tracking engineers measured the position of Venera 3 using thirteen hundred distance measurements, five thousand speed measurements, and seven thousand measurements of the angle to Earth. The course correction was so accurate that Venera 3 would have hit the planet even if the aiming error had been ten to fifteen times as great. The course correction also had to ensure that the spacecraft arrived at Venus when it was in line of sight with the Soviet tracking station.

Venera 3 was a twin of the Venera 2 launched four days earlier; however, Venera 2 carried a photographic payload, whereas Venera 3 carried a 90-centimeter-diameter, 337-kilogram planetary landing capsule, which was intended to parachute to the surface. The two spacecraft were to pass on opposite sides of Venus and provide complementary data about Venus.

Investigations of deep space during the cruise phase of the Venera 3 mission included measurements of the interplanetary magnetic field, cosmic rays, low-energy charged particles, magnitude and energy spectra of solar plasma, micrometeorites, and long-wavelength cosmic radio emanations at wavelengths up to 15 kilometers.

Venera 3’s objectives at Venus included close-up radio studies of the planet’s surface using long-wave interferometry and determination of the characteristics and water content of the atmosphere and surface. The high temperature and pressure conditions now known to exist on the Venusian surface had not been confirmed at the time of the Venera 3 flight. Some Soviet scientists thought the high surface temperature readings sent back by the previous American Mariner 2 probe to Venus were really upper atmospheric temperatures and hoped that the surface conditions were more moderate. Because of this uncertainty, the descent capsule carried surface phase sensors to determine if it had landed on a solid surface or in an ocean.

In case Venera 3’s landing capsule successfully reached the surface of the planet, it carried a 70-millimeter-diameter commemorative sphere with the outline of Earth’s continents. Within the sphere was a medal with the coat of arms of the Soviet Union on one side and the planets of the solar system on the other, showing Earth and Venus in the correct position for the time of Venera 3’s launch. An inscription read “Union of Soviet Socialist Republics, 1965.” At the time of the Venera 3 mission, it was not known that the planet’s atmosphere was so hostile that no living organism could survive. To protect the Venusian environment from Earth contamination, the Venera 3 spacecraft was sterilized by various methods depending upon the tolerance of each spacecraft component. If the components were able to withstand it, portions of the spacecraft were subjected to 115- to 200-degrees-Celsius dry heat. Sensitive electronics and rubber seals that could not be heated were exposed to gamma-ray doses totaling 2.5 million rad. Other portions of the spacecraft were bathed in a 60 percent solution of ethylene oxide diluted by 40 percent methyl bromide. The latter chemical was used to render the former one nonexplosive and was a sterilant. All liquids in the spacecraft were filtered through medical-type asbestos filters.

Venera 3 arrived at Venus on March 1, 1966, and struck the planet at six hours, fifty-six minutes, and twenty-six seconds, Greenwich mean time, at a point only 450 kilometers from the center of the planet’s visible surface. Because the approach to Venus occurred when the planet was between the Sun and Earth, Venera 3 entered the atmosphere on the night side of the planet. Up to that point, the Soviets had successfully contacted the probe sixty-three times during its journey to Venus.

Several days after Venera 3 impacted Venus, the Soviets announced that contact with the spacecraft was lost prior to planetary encounter, and the landing capsule was not ejected. Soviet engineers admitted that as the spacecraft approached Venus, its temperature started to climb above anticipated levels. Initially, the Soviets attributed the loss of the spacecraft to unknown characteristics of Venus or its environment. There was also speculation that the atmosphere of Venus itself caused the radio blackout, but most likely the spacecraft overheated and the orientation system failed during the final hours of the mission. Portions of the landing capsule were likely to survive after being torn loose from the spacecraft bus during atmospheric entry. The landing capsule, however, was not designed to withstand the high-pressure Venusian atmosphere and was likely crushed during free fall.

Significance

The Venera 3 spacecraft has the historical distinction of being the first human-made object to reach the surface of another planet. Although the spacecraft failed only hours before reaching the planet and returned no planetary data, Venera 3 and its companion craft, Venera 2, were the first space probes to cross the distance successfully between Earth and Venus. Much data about interplanetary space between the two planets was relayed by the probe, and the scientific return from the flight to the Venusian planetary encounter was significant. Aside from the importance of being the first object from Earth to reach another planet, the impact of Venera 3 on the surface of Venus was the culmination of five years of repeated Soviet efforts to reach another planet in the solar system. Through the end of 1965, there had been a total of eleven Soviet launch attempts to reach the planet Venus and another seven unsuccessful attempts to reach Mars.

In 1961, two Venus flight attempts resulted in the single craft, Venera 1, entering a heliocentric orbit that would pass approximately 100,000 kilometers from Venus. Communication with Venera 1 failed when the craft was 7.25 million kilometers from Earth. Three more Venus launch attempts on August 25, September 1, and September 12, 1962, failed when their booster’s escape stage failed to reignite in Earth orbit to propel them into a heliocentric orbit.

Repeated planetary flight failures prompted Soviet engineers to launch a diagnostic flight to determine the cause of the malfunctions plaguing Venus probe attempts. This diagnostic flight, launched on November 11, 1963, also failed to leave Earth orbit. Another Venus launch attempt on March 27, 1964, was also trapped in Earth orbit by booster failure. The backup spacecraft for the 1964 Soviet Venus flights, Zond 1, did succeed in leaving Earth orbit on April 2. Bad luck still dogged the Soviet planetary program as communication with Zond 1 was lost on May 14, two months before it was to encounter Venus. Three more Venus probe launches were attempted in 1965. Venera 2 entered a trajectory toward Venus on November 12, and its companion craft, Venera 3, left Earth orbit on November 16. A third 1965 Venus attempt on November 23 exploded in Earth orbit.

Although both Venera 3 and Venera 2 arrived at Venus, the failure of both spacecraft to return any planetary data underscored the weak engineering base in the Soviet space program at that time. As a result of this engineering weakness, two major problems plagued Soviet planetary efforts in the 1960’s. Planetary launches are completed from a temporary Earth orbit. A design fault in the third “escape” stage of the A-2e booster prevented the reliable feed of weightless fuel to its engine while the stage was in Earth orbit. This fault resulted in a large number of early Soviet lunar and planetary launches being stranded in Earth orbit. A second problem that lay in Soviet planetary spacecraft design can be traced to the lack of Soviet space simulation chambers for testing spacecraft designs in a thermal and vacuum environment. Extensive American use of space simulation chambers revealed mission-threatening flaws before launch. The Soviets, however, lacking extensive simulation equipment, were forced to evaluate spacecraft designs in flight, often with less than successful results.

After the Venera 3 probe arrived at Venus, there was some skepticism among Western observers who questioned whether the spacecraft struck Venus by accident or by design. Eventually, however, the planetary impact was regarded as a momentous display of space navigation and the Soviets were congratulated for their achievement.

Bibliography

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Siddiqi, Asif A. Sputnik and the Soviet Space Challenge. Gainesville: University Press of Florida, 2003. An award-winning book that offers a comprehensive and detailed history of the Soviet space program, from its earliest days. An essential resource.

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Wilson, Andrew. Solar System Log. London: Jane’s, 1987. A compilation of all piloted and unpiloted lunar and planetary spaceflights up to mid-1985 by all spacefaring nations. A well-illustrated chronology of the history, spacecraft, mission, and discoveries of all deep-space exploration missions. Suitable for all readers.