The table below shows the number of launches of spacecraft that were destined for Venus. There have been many that have passed by and observed Venus as part of their closest passes on the way to primary target such as Cassini. We will talk more specifically about each and every mission in detail at a later date, but we will be providing details about the most important and successful missions here.

Decade	Number Of Launches
1960s	18
1970s	11
1980s	7
2000s	1
2010s	5

There have been several flybys of the planet, which have not recorded as much relevant information; therefore, we will be focusing on the other probes launched to Venus.

On February 12th, 1961, the Soviet spacecraft Venera 1 was the first probe launched to another planet. An overheated orientation sensor caused it to malfunction, losing contact with Earth before its closest approach to Venus of 100,000 km. However, the probe was first to combine all the necessary features of an interplanetary spacecraft: solar panels, parabolic telemetry antenna, 3-axis stabilization, course-correction engine, and the first launch from parking orbit.

The first successful Venus probe was the American Mariner 2 spacecraft, which flew past Venus in 1962, coming within 35,000 km. A modified Ranger Moon probe, it established that Venus has practically no intrinsic magnetic field and measured the temperature of the planet’s atmosphere to be approximately 500 °C.^[1] In 1974, Mariner 10 swung by Venus on its way to Mercury and took ultraviolet photographs of the clouds, revealing the extraordinarily high wind speeds in the Venusian atmosphere.

On March 1st, 1966 the Venera 3 Soviet space probe crash-landed on Venus, becoming the first spacecraft to reach the surface of another planet.

The descent capsule of Venera 4 entered the atmosphere of Venus on October 18th, 1967, making it the first probe to return direct measurements from another planet’s atmosphere. The capsule measured temperature, pressure, density and performed 11 automatic chemical experiments to analyze the atmosphere. It discovered that the atmosphere of Venus was 95% carbon dioxide

These results were verified and refined by the Venera 5 and Venera 6 in May 1969. But thus far, none of these missions had reached the surface while still transmitting. Venera 4′s battery ran out while still slowly floating through the massive atmosphere, and Venera 5 and 6 were crushed by high pressure 18 km above the surface.

The first successful landing on Venus was by Venera 7 on December 15th, 1970. It remained in contact with Earth for 23 minutes, relaying surface temperatures of 455 °C to 475 °C. Venera 8 landed on July 22nd, 1972. In addition to pressure and temperature profiles, a photometer showed that the clouds of Venus formed a layer, ending over 35 kilometers above the surface. A gamma ray spectrometer analyzed the chemical composition of the crust.

Venera 9 Through 14

The Soviet probe Venera 9 entered orbit on October 22nd, 1975, becoming the first artificial satellite of Venus. A battery of cameras and spectrometers returned information about the planet’s clouds, ionosphere and magnetosphere, as well as performing bi-static radar measurements of the surface. The descent vehicle that separated from Venera 9 landed and then took the first pictures of the surface and analyzing the crust with a gamma ray spectrometer and a densitometer. During descent, pressure, temperature and photometric measurements were made, as well as backscattering and multi-angle scattering (nephelometer) measurements of cloud density. It was discovered that the clouds of Venus are formed in three distinct layers. Venera 10 arrived around this time and performed similar experiments.

Venera 11 and 12 flew past Venus, dropping descent vehicles on December 21st and December 25th respectively. The landers carried colour cameras and a soil drill and analyzer, which unfortunately malfunctioned. Each lander made measurements with a nephelometer, mass spectrometer, gas chromatograph, and a cloud-droplet chemical analyzer using X-ray fluorescence that unexpectedly discovered a large proportion of chlorine in the clouds, in addition to sulfur. Strong lightning activity was also detected.

In 1981, the Soviet Venera 13 sent the first colour image of Venus’s surface and analysed the X-ray fluorescence of an excavated soil sample. The probe operated for a record 127 minutes on the planet’s hostile surface. Also in 1981, the Venera 14 lander detected possible seismic activity in the planet’s crust.

Vega 1 and Vega 2 The objective of the probe was the study of the atmosphere and the exposed surface of the planet. The scientific payload included an ultraviolet spectrometer, temperature and pressure sensors, a water concentration meter, a gas-phase chromatograph, an X-ray spectrometer, a mass spectrometer, and a surface sampling device. A night landing was made so no photos were taken.

The Pioneer Venus Project’s main objective was to investigate the solar wind in the Venusian environment, map the planet’s surface through a radar imaging system and study the characteristics of the upper atmosphere and ionosphere. [2] The Pioneer spacecraft would last from its arrival at Venus in 1978 to 1992 when it was destroyed, at which time atmospheric scientific data gathering ceased.

Venus Express was a mission by the European Space Agency to study the atmosphere and surface characteristics of Venus from orbit. The design was based on ESA’s Mars Express and Rosetta missions. The probe’s main objective was the long-term observation of the Venusian atmosphere, which it is hoped will also contribute to an understanding of Earth’s atmosphere and climate. It also made global maps of Venerean surface temperatures, and attempted to observe signs of life on Earth from a distance.

Venera 15 analyzed and mapped the upper atmosphere with an infrared Fourier spectrometer. From November 11th, 1983 to July 10th, 1984, both satellites mapped the northern third of the planet with synthetic aperture radar. These results provided the first detailed understanding of the surface geology of Venus, including the discovery of unusual massive shield volcanoes such as coronae and arachnoids. Venus had no evidence of plate tectonics, unless the northern third of the planet happened to be a single plate. The altimetry data obtained by the Venera missions had a resolution four times better than Pioneer’s.

On August 10th, 1990, the American Magellan probe, named after the explorer Ferdinand Magellan, arrived at its orbit around the planet and started a mission of detailed radar mapping. Whereas previous probes had created low-resolution radar maps of continent-sized formations, Magellan mapped 98% of the surface with a resolution of approximately 100 meters. The resulting maps were comparable to visible-light photographs of other planets, and are still the most detailed in existence. Magellan greatly improved scientific understanding of the geology of Venus: the probe found no signs of plate tectonics, but the scarcity of impact craters suggested the surface was relatively young, and there were lava channels thousands of kilometers long. After a four-year mission, Magellan, as planned, plunged into the atmosphere on October 11th, 1994, and partly vaporized; some sections are thought to have hit the planet’s surface.

Venus Express successfully assumed a polar orbit on April 11th, 2006. The mission was originally planned to last for two Venusian years, which is about 500 Earth days, but was extended to the end of 2014 until its propellant was exhausted. Some of the first results emerging from Venus Express include evidence of past oceans, the discovery of a huge double atmospheric vortex at the south pole, and the detection of hydroxyl in the atmosphere.

Akatsuki was launched on May 20th, 2010, by JAXA, and was planned to enter Venusian orbit in December 2010. However, the orbital insertion maneuver failed and the spacecraft was left in heliocentric orbit. It was placed on an alternative elliptical Venerian orbit on December 7th, 2015. The probe then imaged the surface in ultraviolet, infrared, microwaves, and radio, and looked for evidence of lightning and volcanism on the planet. Astronomers working on the mission reported detecting a possible gravity wave that occurred on the planet Venus in December 2015.[3]

Sources And Further Reading

Check out the Planetary Bodies Category for previous and upcoming articles on the solar system planets.

[1] = Mayer, C. H.; McCollough, T. P.; Sloanaker, R. M. (1958). “Observations of Venus at 3.15-CM Wave Length”. Astrophysical Journal. 127: 1–9. Bibcode:1958ApJ…127….1M. doi:10.1086/146433.
[2] = https://www.nasa.gov/mission_pages/pioneer-venus/
[3] = Chang, Kenneth (16 January 2017). “Venus Smiled, With a Mysterious Wave Across Its Atmosphere”. New York Times.