Loading
Loading...

Astronomy – Planet Venus

Venus photographed by the Magellan spacecraft

Venus taken from the Magellan spacecraft in 1991.

Stripping away the clouds from its hot, thick, corrosive atmosphere, the surface of Venus is
revealed to be a tortured volcanic landscape scarred by vast forces from the planet’s interior.
This false-colour image of Venus was created by bouncing radio signals off the planet’s surface.
Unlike visible light, radio waves can penetrate the thick layers of cloud, allowing us to map the planet in detail.

After the description of Venus there are details of the spacecraft that have visited the planet, landers, orbiters and fly-bys.

Some Basic Facts about Venus

Venus, the second planet in the Solar System from the Sun, has no known natural satellites (but see below) or rings.

It orbits the Sun once in 224.698 Earth days. All the planets of the Solar System orbit the Sun in a counter-clockwise direction as viewed from above the Sun’s north pole. Most planets also rotate on their axis in a counter-clockwise direction, but Venus rotates clockwise (retrograde) once every 243 Earth days, the slowest rotation period of any planet. Its surface temperature averages 462° C.

Its semi-major axis is 108,208,000 km, with its distance from the Sun ranging from 107,477,000 km to 108,939,000 km; its orbital eccentricity is 0.006 756, the smallest (most circular) of all the planets.

Its radius is 6,051.8±1.0 km, almost the same as the Earth’s, giving it a surface area of 4.60×108 km2. Its mass is 4.8685×1024 kg (0.815 of the Earth’s mass).

Venus’s atmospheric surface pressure is 92 bar (i.e. 92 times the Earth’s) and its atmosphere is made up of about 96.5% carbon dioxide, 3.5% nitrogen, and traces of sulphur dioxide, argon, water vapour, carbon monoxide, helium, neon, carbonyl sulphide, hydrogen chloride and hydrogen fluoride.

More about Venus from NASA; also see spacecraft that have visited the planet.

Planet Venus

Earth’s Twin, but Nothing Like a Twin!

Venus is shrouded by an opaque layer of highly reflective clouds of sulphuric acid, preventing its surface from being seen from space in visible light. It has the densest atmosphere of the four terrestrial planets (Mercury, Venus, Earth and Mars), consisting mostly of carbon dioxide. With a mean surface temperature of 735 K, Venus is by far the hottest planet in the Solar System. It has no carbon cycle to lock carbon back into rocks and surface features, nor does it seem to have any organic life to absorb it in biomass. Venus may have possessed oceans in the past, but these would have vapourized as the temperature rose due to the runaway greenhouse effect. The water has most probably photodissociated, and, because of the lack of a planetary magnetic field, the free hydrogen has been swept into interplanetary space by the solar wind. Venus’s surface is a dry desertscape interspersed with slab-like rocks and periodically refreshed by volcanism. Not the place for a holiday!

Clementine startracker image of the Moon obscuring the Sun, with Venus at the top.


Computer generated 3-dimensional perspective view of the “crater farm” on Venus, consisting of the 37.3 km diameter Saskia in the foreground (28.6° S, 337.1° E), 47.6 km Danilova (26.35° S, 337.25° E) to the left, and 62.7 km Aglaonice to the right (26.5° S, 340° E). The image was created by superimposing Magellan images in topography data, and colouring is based on Venera 13 and 14 Lander images.



Venus and the Pleiades

Coronal Mass Ejection from the Sun

A coronal mass ejection approaches Venus in this still from Dynamic Earth: Exploring Earth’s Climate Engine, a high-resolution movie made by NASA playing at planetariums around the world. This section of the film explores the power of the sun and how its energy drives the climate on Earth, and was created by NASA’s Goddard Scientific Visualization Studio

Transits of Venus


Venus in Transit across the Sun’s face on 8th June 2004

Transits of Venus (when Venus passes directly in front of the Sun) occur in cycles of 243 years with the current pattern of transits being pairs separated by eight years, at intervals of about 105.5 years or 121.5 years

In these photos, Venus is a small black dot on the surface of the Sun. The violent turbulence of the Sun’s surface can be seen; especially in the right-hand photograph you can see the lines of magnetic force causing solar flares.

On 5th and 6th June 2012, was the last Venus transit of the 21st century. The previous pair of transits were in December 1874 and December 1882. The next transits of Venus will be on 10th and 11th December, 2117, and in December 2125.

Venus in Transit on 5-6 June 2012

[Centre] An ultra-high definition view of the transit of Venus on 6th June 2012 captured by NASA’s Solar Dynamics Observatory

See this report that Venus orbits the Sun within a huge band of dust.


Satellites and Quasi-Satellites

Venus has no natural satellite, though the asteroid 2002 VE68 which has a diameter of about 200 m currently maintains a quasi-orbital relationship with it; from the point of view of Venus, it appears to travel around it during one Venusian year but it actually orbits the Sun, not Venus. It seems to have been co-orbital with Venus for only the last 7,000 years, and is destined to be ejected from this orbital arrangement about 500 years from now. This is an example showing how dynamic the structure of the Solar System really is.

2002 VE68 is included in the Minor Planet Center list of Potentially Hazardous Asteroids (PHAs) as it comes to within 0.05 AU of the Earth relatively frequently. Approaches as close as 0.04 AU occur with a periodicity of 8 years due to its near 8:13 resonance with the Earth. It was discovered during one of these close approaches (11th November 2002). During the last close encounter on 7th November 2010, 2002 VE68 approached Earth within 0.035 AU (13.6 lunar distances), brightening below 15th magnitude. Its next fly-by with the Earth will take place on 4th November 2018 at 0.038 AU (5,700,000 km). Numerical simulations indicate that an actual collision with Earth during the next 10,000 years is not likely, although dangerously close approaches to about 0.002 AU are possible.

In the 17th century, Giovanni Cassini reported a moon orbiting Venus, which was named Neith and numerous sightings were reported over the following 200 years, but most were determined to be stars in the vicinity. A study of models of the early Solar System (at the California Institute of Technology) shows Venus probably had at least one moon created by a huge impact billions of years ago. About 10 million years later, according to the study, another impact reversed the planet’s spin direction and caused the Venusian moon gradually to spiral inward until it collided and merged with Venus. If later impacts created moons, these also were absorbed in the same way.

List of All Spacecraft Missions to Venus

This list includes all known missions to Venus (including Failures) to date. Other missions that are indevelopment or proposals are listed at the end of this table.
Spacecraft Launch date Operator Mission Outcome Remarks
Sputnik 7 (Tyazhely Sputnik, Venera 1VA No.1) 4 February 1961 USSR Lander Failure Intended Venus flyby; Failed to escape from Earth orbit
Venera 1 12 February 1961 USSR Flyby Failure Contact lost 7 days after launch on 12 February 1961; first spacecraft to fly by another planet, 19 – 20 May 1961
Mariner 1 22 July 1962 NASA (United States) Flyby Failure Guidance failure shortly after launch
Sputnik 19 (Venera 2MV-1 No.1) 25 August 1962 USSR Lander Failure Failed to escape from Earth orbit
Sputnik 20 (Venera 2MV-1 No.2) 1 September 1962 USSR Lander Failure Failed to escape from Earth orbit
Sputnik 21 (Venera 2MV-2 No.1) 12 September 1962 USSR Flyby Failure Third stage exploded
Mariner 2 14 December 1962 NASA (United States) Flyby Successful 19 December 1962 flew by Venus; first successful Venus flyby; minimum distance 34,773 km
Cosmos 21 (Venera 3MV-1 No.1; tentatively identified) 11 November 1963 USSR Flyby Failure Third stage exploded; orbit decayed 14 November 1963
Venera 1964A (Venera 3MV-1 No.2, tentatively identified) 19 February 1964 USSR Flyby Failure Failed to reach Earth orbit
Venera 1964B (tentatively identified) 1 March 1964 USSR Flyby Failure Failed to reach Earth orbit
Cosmos 27 (Zond 3MV-1 No.3) 27 March 1964 USSR Flyby Failure Failed to escape Earth orbit
Zond 1 (tentatively identified) 2 April 1964 USSR Flyby and possible Lander Failure Communications lost 14 May 1964 en route; Venus fly-by 14 July 1964
Cosmos 96 (Venera-3MV-4 No.6) 23 November 1965 USSR Flyby or Lander Failure Exploded? Low Earth orbit until 9 December 1965
Venera 1965A (tentatively identified) 26 November 1965 USSR Flyby Failure Launch vehicle failure?
Venera 2 12 November 1965 USSR Flyby Failure Ceased to operate en route; closest approach to Venus (24,000 km) on 27 February 1966
Venera 3 16 November 1965 USSR Lander Failure Contact lost before arrival; first spacecraft to impact on the surface of another planet; possibly crashed on 1 March 1966
Kosmos 167 (Venera-4V-1 No.311) 17 June 1967 USSR Lander Failure Failed to escape Earth orbit; re-entry on 25 June 1967
Venera 4 12 June 1967 USSR Atmospheric probe Successful 18 October 1967 arrived at Venus; continued to transmit to an altitude of 25 km
Mariner 5 14 June 1967 NASA (United States) Flyby Successful 14 October 1967 flew by at minimum distance 5,000 km
Venera 5 5 January 1969 USSR Atmospheric probe Successful 16 May 1969, transmitted atmospheric data for 53 minutes, to an altitude of about 26 km
Venera 6 10 January 1969 USSR Atmospheric probe Successful 17 May 1969, transmitted atmospheric data for 51 minutes, to an altitude of perhaps 10–12 km
Cosmos 359 (Venera-4V-1 No.631) 22 August 1970 USSR Lander? Failure Failed to escape elliptical Earth orbit
Venera 7 17 August 1970 USSR Lander Successful 15 December 1970, first successful landing on another planet; signals returned from surface for 23 minutes
Cosmos 482 31 March 1972 USSR Lander? Failure Failed to escape Earth orbit; 3 April 1972 parts crashed in New Zealand
Venera 8 27 March 1972 USSR Lander Successful 22 July 1972, signals returned from surface for 50 minutes
Mariner 10 3 November 1973 NASA (United States) Flyby Successful On 5 February 1974 flew by at minimum distance 5768 km, en route to Mercury; first use of gravity assist by an interplanetary spacecraft
Venera 9 Orbiter 1975 USSR Orbiter Successful First spacecraft to orbit Venus; communications relay for Lander; atmospheric and magnetic studies
Venera 9 Lander 22 October 1975 USSR Lander Successful First images from the surface; operated on surface for 53 minutes
Venera 10 Orbiter 1975 USSR Orbiter Successful Communications relay for Lander; atmospheric and magnetic studies
Venera 10 Lander 23 October 1975 USSR Lander Successful Transmitted from surface for 65 minutes
Pioneer Venus Orbiter NASA (United States) Orbiter Successful Atmospheric and magnetic studies, 4 December 1978 – 1992
Pioneer Venus Multiprobe bus 9 December 1978 NASA (United States) Probe transporter Successful Deployed four Atmospheric probes, then burnt up in Venusian atmosphere, continuing to transmit to 110 km altitude
Pioneer Venus Multiprobe large probe 9 December 1978 NASA (United States) Atmospheric probe Successful Deployed four Atmospheric probes, then burnt up in Venusian atmosphere, continuing to transmit to 110 km altitude
Pioneer Venus Multiprobe north probe 9 December 1978 NASA (United States) Atmospheric probe Successful
Pioneer Venus Multiprobe day probe 9 December 1978 NASA (United States) Atmospheric probe Successful Survived impact and continued to transmit from surface for over an hour
Pioneer Venus Multiprobe night probe 9 December 1978 NASA (United States) Atmospheric probe Successful
Venera 12 flight platform 21 December 1978 SAS (USSR) Flyby Successful Minimum distance 34,000 km; deployed Lander and then acted as communications relay
Venera 12 descent craft 21 December 1978 SAS (USSR) Lander Partial success Soft landing; transmissions returned for 110 minutes; failure of some instruments
Venera 11 flight platform (identical to Venera 12) 25 December 1978 SAS (USSR) Flyby Successful Minimum distance 34,000 km; deployed Lander and then acted as communications relay
Venera 11 descent craft 25 December 1978 SAS (USSR) Lander Partial success Soft landing; transmissions returned for 95 minutes; failure of some instruments
Venera 13 bus 1 March 1982 SAS (USSR) Flyby Successful Deployed Lander and then acted as communications relay
Venera 13 descent craft 1 March 1982 SAS (USSR) Lander Successful Survived on surface for 127 minutes
Venera 14 bus (identical to Venera 13) 5 March 1982 SAS (USSR) Flyby Successful Deployed Lander and then acted as communications relay
Venera 14 descent craft 5 March 1982 SAS (USSR) Lander Successful Survived on surface for 57 minutes
Venera 15 1983–1984 SAS (USSR) Orbiter Successful Radar mapping
Venera 16 (identical to Venera 15) 1983–1984 SAS (USSR) Orbiter Successful Radar mapping
Vega 1 11 June 1985 SAS (USSR) Flyby Successful Went on to fly by Halley’s comet
Vega 1 lander 11 June 1985 SAS (USSR) Lander Failure Instruments deployed prematurely
Vega 1 atmospheric balloon 11 June 1985 SAS (USSR) Atmospheric balloon Successful Floated at an altitude of about 54 km and transmitted for around 46 hours
Vega 2 15 June 1985 SAS (USSR) Flyby Successful Went on to fly by Halley’s comet
Vega 2 lander 11 June 1985 SAS (USSR) Lander Successful Transmitted from surface for 56 minutes
Vega 2 atmospheric balloon 11 June 1985 SAS (USSR) Atmospheric balloon Successful Floated at an altitude of about 54 km and transmitted for around 46 hours
Galileo 10 February 1990 NASA (United States) Flyby Successful Gravity assist en route to Jupiter; minimum distance 16,000 km
Magellan 10 August 1990 – 12 October 1994 NASA (United States) Orbiter Successful Global radar mapping
Cassini NASA (United States)
/ESA (Europe)/
ASI (Italy)		 Flyby Successful 26 April 1998 and 24 June 1999: gravity assists en route to Saturn
Venus Express 11 April 2006 – 18 January 2015 ESA (Europe) Orbiter Successful Atmospheric studies; planetary imaging; magnetic observations
MESSENGER 24 October 2006 and 6 June 2007 NASA (United States) Flybys Both Successful Gravity assists only; minimum distances 2990 km and 300 km, en route to Mercury
Akatsuki (PLANET-C) 7 December 2010 (Venus Flyby) JAXA (Japan) Orbiter Failed to attain Venus orbit in 2010 In Venus orbit (orbit insertion on 7 December 2015); payload may be functional
IKAROS 8 December 2010 JAXA (Japan) Flyby Successful Solar sail technology development / interplanetary space exploration
Shin’en (UNITEC-1) December 2010? UNISEC (Japan) Flyby Failure Contact lost shortly after launch

Proposed Spacecraft

Venera (USSR)
(and Venera Failures identified as Kosmos)

The Venera (Cyrillic: Венера) series probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus. As with some of the Soviet Union’s other planetary probes, the later versions were launched in pairs with a second vehicle being launched soon after the first of the pair.

Ten probes from the Venera series successfully landed on Venus and transmitted data from the surface, including the two Vega program probes. In addition, thirteen Venera probes successfully transmitted data from the atmosphere of Venus.

The entire series could be considered highly successful. Unfortunately the surface conditions on Venus are extreme, which meant that the probes only survived on the surface for a duration of 23 minutes (initial probes) up to about two hours (final probes).

Venera 1VA
(1961 Beta 1), the first Soviet attempt at a fly-by probe to Venus was launched on 4th February 1961, but failed to leave Earth orbit. In keeping with the (then) Soviet policy of not announcing details on failed missions, this and several other failed attempts at Venus fly-by probes, but were not announced as planetary missions at the time, and hence did not officially receive the “Venera” designation.
Venera 1
(1961 Gamma 1), Venera-1VA No.2 and known in the West as Sputnik 8, was launched on 12th February 1961.
Venera 2MV-1 No.1
(1962 Alpha Pi 1) (known in the West first as Sputnik 23 then as Sputnik 19) was an atmospheric probe, launched on 25th August 1962. Its escape stage failed; it re-entered three days later.
Venera 2MV-1 No.2
(1962 Alpha Tau 1) (known in the West first as Sputnik 24 then as Sputnik 20) was an atmospheric probe, launched on 1st September 1962. Its escape stage failed; and it re-entered five days later.
Venera 2MV-2 No.1
(1962 Alpha Phi 1) (known in the West first as Sputnik 25 then as Sputnik 21) was a fly-by mission, launched on 12th September 1962. The third stage exploded and the spacecraft was destroyed.
Venera 3MV-1 No.2
(1964-F01) or No. 4A, also known as Venera 1964A in the West, was a Soviet spacecraft, which was launched on 19th February 1964 as part of the Zond programme. Due to a problem with its carrier rocket third stage it failed to reach low Earth orbit. It was intended to fly-by Venus.
Kosmos 27
(Cyrillic: Космос) (1964-014A), also known as Zond 3MV-1 No.3 was a space mission intended as a Venus fly-by. The spacecraft had an upper stage malfunction resulting in it failing to leave low Earth orbit. It was launched on 27th March 1964. (Most of the Zond spacecraft were intended to go to the vicinity of the Moon.
Venera 2
(1965-091A), Venera-3MV-4 No.4 was launched on 12th November 1965. It failed to return data after flying past Venus. The spacecraft made its closest approach to Venus on 27th February 1966, at a distance of 24,000 km. During the fly-by, all of Venera 2’s instruments were activated, requiring that radio contact with the spacecraft be suspended. The probe was to have stored data using onboard recorders, and then transmitted it to Earth once contact was restored. Following the fly-by the spacecraft failed to reestablish communications with the ground. It was declared lost on 4th March. An investigation into the failure determined that the spacecraft had overheated due to a radiator malfunction.
Venera 3
(1965-092A) or Venera-3MV No.3 was to explore the surface of Venus. It was launched on 16th November 1965. The probe possibly crash-landed on Venus on 1st March 1966. However, its communications systems failed before it reached the planet.
Kosmos 96
(1965-094A) or Venera-3MV-4 No.6 was a Soviet spacecraft intended to explore the atmosphere of Venus. It was launched on 23rd November 1965, but failed to leave Earth orbit, and reentered the atmosphere. It is believed by some researchers to have crashed near Kecksburg, Pennsylvania on 9th December 1965, an event which became known as the “Kecksburg Incident” among UFO researchers; however analysis found the spacecraft probably reentered several hours before the sightings. A 3MV-4 spacecraft launched as part of the Venera programme, Kosmos 96 was to have made a fly-by of Venus, however due to a launch failure it did not depart low Earth orbit. Late in third stage flight, a fuel line ruptured, causing one of the engine’s combustion chambers to explode. The rocket tumbled out of control, and as a result the fourth stage, a Blok-L, failed to ignite. The spacecraft was deployed into a low Earth orbit with a perigee of 209 km, an apogee of 261 km, and 51.9° inclination to the equator.

The 3MV-4 No.6 spacecraft was originally built for a mission to Mars, with launch scheduled for late 1964, however it was not launched by the end of the launch window, and was consequently repurposed, along with the spacecraft which were launched as Venera 2 and Venera 3, to explore Venus. Had it departed Earth orbit it would have received the next designation in the Venera series, at the time Venera 4.

Venera 4
(1967-058A) was launched on 12th June 1967. It was the first successful probe to perform in-place analysis of the environment of another planet. It may also have been the first probe to land on another planet, with the fate of its predecessor Venera 3 being unclear. Venera 4 provided the first chemical analysis of the Venusian atmosphere, showing it to be primarily carbon dioxide with a few percent of nitrogen and below one percent of oxygen and water vapours. The probe detected a weak magnetic field and no radiation field. The outer atmospheric layer contained very little hydrogen and no atomic oxygen. It sent the first direct measurements proving that Venus was extremely hot, that the atmosphere was far denser than expected, and that Venus had lost most of its water long ago. It continued to transmit atmospheric data to an altitude of about 26 km.
Kosmos 167
(1967-063A) or Venera-4V-1 No.311 was intended to land on Venus, however due to a launch failure it did not depart low Earth orbit. It was launched on 17th June 1967. Its escape stage failed and it never departed its parking orbit. It re-entered eight days later on 25th June. Due to a turbopump cooling problem, the rocket’s Blok-L fourth stage failed to ignite, and as a result the spacecraft never departed its parking orbit. It was deployed into a low Earth orbit with a perigee of 187 km, an apogee of 262 km, and 51.8° inclination to the equator. The spacecraft was named Kosmos 167, part of a series typically used for military and experimental satellites in order to cover up the failure; had it departed Earth orbit it would have received the next designation in the Venera series, at the time Venera 5.
Venera 5

Venera 5
(1969-001A) was also a successful atmospheric probe of Venus and was launched on 5th January 1969. When the atmosphere of Venus was approached, a capsule weighing 405 kg and containing scientific instruments was jettisoned from the main spacecraft. During satellite descent towards the surface of Venus, a parachute opened to slow the rate of descent. For 53 minutes on 16th May 1969 it transmitted data while the capsule was suspended from the parachute to an altitude of 25 km.
Venera 6
(1969-002A) was a successful atmospheric probe of Venus, launched on 10th January 1969. It was similar to but stronger than Venera 4, and on 17th May 1969 transmitted data for 51 minutes, to an altitude of perhaps 10 to 12 km.
Venera 7
(1970-060A), launched on 17th August 1970 made the first successful landing on another planet on 15th December 1970; signals were returned from the surface for 23 minutes. It was the first probe designed to survive Venus surface conditions and to make a soft landing. Massively overbuilt to ensure survival, it had few experiments on board, and scientific output from the mission was further limited due to an internal switchboard failure which stuck in the “transmit temperature” position. Still, the control scientists succeeded in extrapolating the pressure (90 atm) from the temperature data (465 °C), which resulted from the first direct surface measurements. The Doppler measurements of the Venera 4 to 7 probes were the first evidence of the existence of high-speed zonal winds (up to 100 m/s) in the Venusian atmosphere (super rotation). Venera 7’s parachute failed shortly before landing, fortunately very close to the surface. It impacted at 17 m/s and toppled over, but survived. Due to the resultant antenna misalignment, the radio signal was very weak, but was detected (with temperature telemetry) for 23 more minutes before its batteries expired. Thus, it became, on 15th December 1970, the first man-made probe to transmit data from the surface of Venus.
Kosmos 359
(1970-065A) or Venera-4V-1 No.631 was intended to land on Venus; it was launched on 22nd August 1970. Its escape stage failed and it ended up in an elliptical Earth orbit.
Venera 8
(1972-021A) was launched on 27th March 1972, and made a successful landing on Venus on 22nd July 1972, having entered the atmosphere at 08:37 UT; signals were returned from the surface for 50 minutes.
Kosmos 482
(1972-023A) was launched on 31st March 1972. Its escape stage exploded during trans-Venus injection; some pieces re-entered and others remained in Earth orbit. Kosmos 482 was launched four days after the Venera 8 atmospheric probe and may have been similar in design and mission plan. After achieving an Earth parking orbit, the spacecraft made an apparent attempt to launch into a Venus transfer trajectory. It separated into four pieces, two of which remained in low Earth orbit and decayed within 48 hours into south New Zealand (known as the “Ashburton balls incident”), and two pieces (presumably the payload and detached engine unit) went into a higher 210×9800 km orbit. It is thought that a malfunction resulted in an engine burn which did not achieve sufficient velocity for the Venus transfer and left the payload in this elliptical Earth orbit. At 1 am on 3rd April 1972, four red-hot 13.6 kg titanium alloy balls landed within a 16 km radius of each other just outside Ashburton, New Zealand. The 38 cm-diameter spheres scorched holes in crops and made deep indentations in the soil, but no one was injured. A similarly shaped object was discovered near Eiffelton, New Zealand, in 1978. Space law required that the space junk be returned to its national owner, but the Soviets denied knowledge or ownership of the satellite. Ownership therefore fell to the farmer upon whose property the satellite fell. Kosmos 482 was thoroughly analysed by New Zealand scientists which determined that they were Soviet in origin because of manufacturing marks and the high-tech welding of the titanium. The scientists concluded that they were probably gas pressure vessels of a kind used in the launching rocket for a satellite or space vehicle and had decayed in the atmosphere.
Venera 9
(1975-050D) (4V-1 No. 660), launched on 8th June 1975 was the first spacecraft to orbit Venus; it was a communications relay for a lander and made atmospheric and magnetic studies; it entered orbit on 20th October 1975 and on 22nd October the lander sent its first images from the surface, operating on the surface for 53 minutes. Venera 9 measured clouds that were 30 to 40 km thick with bases at 30 to35 km altitude. It also measured atmospheric chemicals including hydrochloric acid, hydrofluoric acid, bromine, and iodine.
Venera 10
(1975-054D) also orbited Venus; it was launched on 14th June 1975, and was a communications relay for a lander and made atmospheric and magnetic studies; on 23rd October 1975 the lander sent its images from the surface for 65 minutes.
Venera 11
(SAS) (1978-084D), launched on 9th September 1978 was identical to Venera 12; the flight platform successfully flew by Venus on 25th December 1978 at a minimum distance of 34,000 km;, deployed the lander and then acted as a communications relay. The descent craft made a soft landing on 25th December 1978; transmissions were returned for 95 minutes but with the failure of some instruments.
Venera 12
(SAS) (1978-086A), launched on 14th September 1978, was a fly-by flight platform, passing Venus at a minimum distance of 34,000 km on 19th December 1978; it deployed a lander and then acted as a communications relay. The lander was a partial success, making a soft landing; transmissions were returned for 110 minutes but there was a failure of some instruments.
Venera 13
(SAS) (1981-106A), launched on 30th October 1978, had a fly-by bus which, on 1st March 1982 deployed its lander and then acted as a communications relay. The descent craft lander was a success and survived on the surface for 127 minutes on 1st March 1982.
Venera 14
(SAS) (1981-110A) was identical to Venera 13. It was launched on 4th November 1978. Its bus deployed the lander on 5th March 1982 and then acted as a communications relay; the descent craft survived on the surface for 57 minutes.
Venera 15
(SAS) (1983-053A) was launched on 2nd June 1983 and reached Venus’ orbit on 10th October 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 16, with its orbital plane shifted by an angle of approximately 4° relative to the another probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a periapsis of about 1000 km, at 62°N latitude, and apoapsis of 65000 km, with an inclination about 90°, the orbital period being about 24 hours. Together with Venera 16, the spacecraft imaged the area from the north pole down to about 30°N latitude (approximately 25% of Venus’ surface) over the 8 months of mapping operations.
Venera 16
(SAS) (1983-054A), an identical craft, was launched on 7th June 1983 and reached Venus’ orbit on 11th October 1983, and also performed radar mapping in 1983 to 1984.

Venera-D (Russia)

The Venera-D (Cyrillic: Венера–Д) probe is a proposed Russian space probe to Venus, to be launched around 2024. Venera-D’s prime purpose is to make radar remote-sensing observations around the planet Venus in a manner similar to that of the Venera 15 and Venera 16 probes in the 1980s or the U.S. Magellan in the 1990s, but with the use of more powerful radar. Venera-D is also intended to map future landing sites. A lander, based on the Venera design, is also planned, capable of surviving for a long duration on the planet’s surface.

Venera-D will be the first Venus probe launched by the Russian Federation (the earlier Venera probes were launched by the former Soviet Union). Venera-D will serve as the flagship for a new generation of Russian-built Venus probes, culminating with a lander capable of withstanding the harsh Venusian environment for more than the 1½ hours logged by the Soviet-era probes. In order to keep research and development costs down, the new Venera-D probe will most likely resemble the Soviet-era probes, but will rely on new technologies developed by Russia since its last Venus missions (Vega 1 and Vega 2 in 1985). Venera-D will most likely be launched on the Proton booster, but may be designed to be launched on the more powerful Angara rocket instead.

Pioneer Venus Orbiter (NASA)

Pioneer Venus Orbiter (1978-051A) or Pioneer Venus 1 or Pioneer 12 was launched on 20th May 1978. It orbited Venus and made atmospheric and magnetic studies from 4th December 1978 until August 1992 when its orbit decayed.

Shin’en (UNITEC-1) (Japan)

Shin’en (2010-020F) was launched on 20th May 2010 with IKAROS and several other Japanese satellites. Shin’en, known before launch as UNITEC-1 or UNISEC Technology Experiment Carrier 1, is a Japanese student spacecraft which was intended to make a flyby of Venus in order to study the effects of interplanetary spaceflight on spacecraft computers. In doing so, it was intended to become the first student-built spacecraft to operate beyond geocentric orbit. It was operated by UNISEC, a collaboration between several Japanese universities. Contact was lost shortly after launch.

Vega Probes to Venus and Halley’s Comet
(USSR, Soviet Academy of Sciences)


Vega missions to Venus and Halley’s comet

The Vega program was a series of Venus missions which also took advantage of the appearance of Comet 1P/Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union (who provided the spacecraft and launch vehicle) and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland, Czechoslovakia, France, and the Federal Republic of Germany in December 1984. They had a two-part mission to investigate Venus and also flyby Halley’s Comet. The craft were designated Vega, a contraction of “Venera” and “Gallei” (Russian words for “Venus” and “Halley”, respectively). The spacecraft design was based on the previous Venera 9 and Venera 10 missions.

Venus Missions

The surface landers of Vega 1 and Vega 2 were identical to those of the previous five Venera missions. The objective of the Vega probes was the study of the atmosphere and the exposed surface of the planet. The scientific payload included a UV 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. Several of these scientific tools (the UV spectrometer, the mass spectrograph, and the devices to measure pressure and temperature) were developed in collaboration with French scientists.

Vega 1 (1984-125A) was launched on 15th December 1984. It made a successful Venus fly-by on 11th June 1985, and released a lander and balloon. Its Venus lander (1984-125E) failed because its instruments were deployed prematurely. Its atmospheric balloon (1984-125F) floated at an altitude of about 54 km and transmitted for around 46 hours.

The Vega 1 Lander/Balloon capsule entered the Venus atmosphere (125 km altitude) on 11th June 1985 at roughly 11 km/s. The parachute attached to the landing craft cap opened at an altitude of 64 km. The cap and parachute were released 15 seconds later at 63 km altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at 61 km altitude, at 8.1° N, 176.9°E. A second parachute opened at an altitude of 55 km, 200 seconds after entry, extracting the furled balloon. The balloon was inflated 100 seconds later at 54 km and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly 50 km and the balloon floated back to a stable height between 53 and 54 km some 15 to 25 minutes after entry. The mean stable height was 53.6 km, with a pressure of 535 mbar and a temperature of 300 to 310 K in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 69 m/s at nearly constant latitude. The probe crossed the terminator from night to day at 12:20 UT on 12th June after traversing 8,500 km. The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 13th June from 8.1° N, 68.8° E after a total traverse distance of 11,600 km. It is not known how much farther the balloon travelled after the final communication.

Vega 2 (1984-128A) was launched on 21st December 1984. It made a successful Venus fly-by on 15th June 1985, and went on to fly by Halley’s comet. Its lander (1984-128E) was a success and it transmitted from the surface for 56 minutes. Its atmospheric balloon (1984-128F) floated at an altitude of about 54 km and transmitted for around 46 hours.

The Vega 2 lander touched down on 15th June 1985 at around 7.14°S 177.67°E, in the northern region of Aphrodite Terra. The altitude of the touchdown site was 0.1 km above the planetary mean radius. The measured pressure at the landing site was 91 atm and the temperature was 736 K. The surface sample was found to be an anorthosite-troctolite rock, rarely found on Earth, but present in the lunar highlands, leading to the conclusion that the area was probably the oldest explored by any Venera vehicle.

The Vega 2 Lander/Balloon capsule entered the Venus atmosphere (125 km altitude) on 15th June 1985 at roughly 11 km/s. The parachute attached to the landing craft cap opened at an altitude of 64 km. The cap and parachute were released 15 seconds later at 63 km altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at 61 km altitude, at 7.45 degrees S, 179.8 degrees east. A second parachute opened at an altitude of 55 km, 200 seconds after entry, extracting the furled balloon. The balloon was inflated 100 seconds later at 54 km and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly 50 km and the balloon floated back to a stable height between 53 and 54 km some 15 to 25 minutes after entry. The mean stable height was 53.6 km, with a pressure of 535 mbar and a temperature of 308 to 316 K in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 66 m/s at nearly constant latitude. The probe crossed the terminator from night to day at 9:10 UT on 16th June after traversing 7,400 km. The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 17th June from 7.5° S, 76.3° E after a total traverse distance of 11,100 km. It is not known how much further the balloon travelled after the final communication.

Halley’s Comet Missions

After their encounters with Venus, the Vegas’ motherships were redirected by Venus’ gravity to intercept Halley’s Comet (officially designated 1P/Halley). Sling-shot manoeuvres sent them on to fly by Halley’s comet.

Images started to be returned from Vega 1 on 4th March 1986, and were used to help pinpoint Giotto’s close flyby of the comet. The early images from Vega showed two bright areas on the comet, which were initially interpreted as a double nucleus. The bright areas would later turn out to be two jets emitting from the comet. The images also showed the nucleus to be dark, and the infrared spectrometer readings measured a nucleus temperature of 300 K to 400 K, much warmer than expected for an ice body. The conclusion was that the comet had a thin layer on its surface covering an icy body.

Vega 1 made its closest approach to the nucleus on 6th March at around 8,889 km (at 07:20:06 UT). It took more than 500 pictures via different filters as it flew through the gas cloud around the coma. Although the spacecraft was battered by dust, none of the instruments were disabled during the encounter.

The data intensive examination of the comet covered only the three hours around closest approach. They were intended to measure the physical parameters of the nucleus, such as dimensions, shape, temperature and surface properties, as well as to study the structure and dynamics of the coma, the gas composition close to the nucleus, the dust particles’ composition and mass distribution as functions of distance to the nucleus and the cometary-solar wind interaction.

The Vega images showed the nucleus to be about 14 km long with a rotation period of about 53 hours. The dust mass spectrometer detected material similar to the composition of carbonaceous chondrites meteorites and also detected clathrate ice.

After subsequent imaging sessions on 7th and 8th March 1986, Vega 1 headed out to deep space.

Vega 2 (1984-128A), launched on 21st December 1984, initiated its encounter on 7th March 1986 by taking 100 photos of the comet from a distance of 14 million km. It made its closest approach at 07:20 UT on 9th March 1986 at 8,030 km. The data intensive examination of the comet covered only the three hours around closest approach. They were intended to measure the physical parameters of the nucleus, such as dimensions, shape, temperature and surface properties, as well as to study the structure and dynamics of the coma, the gas composition close to the nucleus, the dust particles’ composition and mass distribution as functions of distance to the nucleus and the cometary–solar wind interaction.

During the encounter, Vega 2 took 700 images of the comet, with better resolution than those from the twin Vega 1, partly due to the presence of less dust outside of the coma at the time. Yet Vega 2 recorded an 80% power loss during the encounter as compared to Vega 1’s 40%.

After further imaging sessions on 10th and 11th March 1986, Vega 2 finished its primary mission.

In total Vega 1 and Vega 2 returned about 1500 images of Comet Halley. Vega 1 ran out of attitude control propellant on 30th January 1987, and contact with Vega 2 continued until 24th March 1987.

Vega 1 and Vega 2 are now in heliocentric orbits.

Magellan (NASA)


Magellan

Magellan (1989-033B) was the first interplanetary mission to be launched from the Space Shuttle (Atlantis, STS-30); Atlantis was launched from the Kennedy Space Center on 4th May 1989 and Magellan was deployed from the shuttle’s payload bay 6 hours 14 minutes into the mission. Two successive Inertial Upper Stage (IUS) propulsion burns placed the spacecraft on its trajectory to Venus about an hour later. Magellan arrived at Venus on 10th August 1990 and was inserted into orbit around Venus at 17:00:00 UTC. It performed until 12th October 1994, a 243-day mission of mapping the planet’s surface with radar.

The Magellan spacecraft, also referred to as the Venus Radar Mapper, was a 1,035-kg robotic space probe, to map the surface of Venus using Synthetic Aperture Radar and measure the planetary gravity. It was the first to use an inertial upper stage booster and was the first spacecraft to test aerobraking as a method for circularizing an orbit. Magellan was the fourth successful, NASA funded mission to Venus and ended an eleven-year U.S. interplanetary exploration hiatus.

NASA has two web-sites about Magellan, for the Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC).

IKAROS and Akatsuki (Japan)


IKAROS solar sail

IKAROS (2010-020E) (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is a Japan Aerospace Exploration Agency (JAXA) experimental spacecraft. The spacecraft was launched on 20th May 2010 together with the Akatsuki (Venus Climate Orbiter) probe and four other small spacecraft into an Earth–Venus transfer heliocentric orbit. IKAROS is the first spacecraft to successfully demonstrate solar-sail technology in interplanetary space. IKAROS flew by Venus on 8th December 2010 at about 80,800 km distance, completing the planned mission successfully, and entered its extended operation phase, for solar sail technology development and interplanetary space exploration.

Akatsuki (2010-020D) was supposed to spend two years orbiting Venus, studying the hot planet’s clouds, atmosphere and weather. It was due to enter orbit around Venus on 6th December 2010, but its engine failed during a crucial orbit-insertion burn, and the probe went off into space. However, officials from JAXA haven’t given up and want the probe to take another shot at Venus during the next available opportunity, which could come as soon as 2015. So they’ve been testing the probe’s main engine, called the “orbit maneouvre engine”.

Pioneer Venus Multiprobe (NASA)


Pioneer Venus Multiprobe

Pioneer Venus Multiprobe (1978-078A) or Pioneer Venus 2 (Pioneer 13) was launched on 8th August 1978. It was a probe transporter bus that carried one large (1978-078D) and three small atmospheric probes, then burnt up in the Venusian atmosphere, continuing to transmit to 110 km altitude on 9th December 1978 until 1992. Its four probes (large probe, north probe, day probe and night probe) were all successful atmospheric probes, and the day probe survived impact and continued to transmit from surface for over an hour. The large probe was released on 16th November 1978, and the three small probes on 20th November. All four probes entered the Venusian atmosphere on 9th December, followed by the bus.

Venus Express (ESA)


Venus Express

Venus Express (2005-045A) was the first Venus exploration mission of the European Space Agency. It was launched by a Soyuz-FG/Fregat rocket from the Baikonur Cosmodrome in Kazakhstan on 9th November 2005 at 03:33:34 UTC. Venus Express has orbited Venus since 11th April 2006, and performed atmospheric studies, planetary imaging and magnetic observations. It finally ran out of power and full contact was lost on 28th November 2014. More detail here.

Mariner (NASA)

Most of the Mariner craft went to Mars, with a few exceptions. See the description of the Mariner program.


Mariner 2

The Mariner 2 craft (1962-041A) was launched on 27th August 1962 to Venus; the mission made the first successful Venus fly-by at a minimum distance of 34,773 km on 19th December 1962.

Mariner 5 (or Mariner Venus 1967) (1967-060A), launched on 14th June 1967, made a successful Venus fly-by at a minimum distance of 5,000 km on 14th October 1967.

Mariner 10 (1973-085A) was launched on 3rd November 1973 at 0545:00 UTC; it made a successful fly-by of Venus at a minimum distance of 5,768 km, en route to Mercury; this was the first use of gravity assist by an interplanetary spacecraft; it then made three fly-bys of Mercury on 29th March 1974 at a minimum distance of 704 km, on 21st September 1974 at 48,069 km, and on 16th March 1975 at 327 km.

Mariner 10 at Venus
Mariner 10 at Venus