Venus was one of the first planets to be visited by spacecraft from Earth. Probes do not last long on the surface, where the atmosphere is 50 times denser than Earth's and temperatures are hot enough to melt lead. Spacecraft headed to Mercury use Venus' gravity to adjust their trajectories; even missions headed to the outer solar system often fly by Venus first.
The European Space Agency's Venus Express studied the planet's ionosphere and atmosphere, enabling scientists to draw important conclusions about the surface.
NASA's MESSENGER spacecraft flew past Venus twice on its way to Mercury.
NASA and the European Space Agency's Cassini-Huygens mission visited Venus twice during its long trek out to Saturn.
NASA's Magellan orbiter mapped over 98% of Venus at a resolution of 100 meters or better using its radar.
NASA's Galileo spacecraft used Venus' gravity to adjust its trajectory on the way to Jupiter.
Vega 1 and 2
En route to comet Halley, The Soviet Union's identical Vega 1 and 2 probes deployed balloons into Venus' atmosphere to measure the temperature, pressure, wind velocity, and visibility as they floated around the planet.
Venera 15 and 16
Venera 15 and 16 created a radar map of Venus during a joint mission lasting 8 months.
Venera 13 and 14
Venera 13 and 14 were identical landers to explore Venus' surface. Venera 13 returned the first color images from the surface.
NASA's Pioneer Venus mission sent 2 spacecraft to study the planet. Pioneer Venus 1 was an orbiter that made a radar map of the surface, while Pioneer Venus 2 consisted of 4 atmospheric probes. One of the probes survived to transmit data for over an hour after it impacted with the surface.
The Venera 10 spacecraft separated into two different sections, an orbiter and a lander, on October 23, 1975. Two days later, the lander touched down on the surface of Venus 2,200 kilometers from the Venera 9 lander, somewhere within a 150 km radius of 15.42° N, 291.51° E. With the orbiter acting as a relay, the lander transmitted images from the surface as well as data about clouds and the surface environment.
The Venera 9 lander separated from the orbiter on October 20, 1975. Two days later, the lander touched down and became the first spacecraft to transmit a picture from the surface of another planet. It landed within a 150-kilometer radius of 31.01° N, 291.64° E. In addition, the lander sent back information on the Venusian clouds, atmospheric composition, and light levels. All of the information was transmitted from the surface to the orbiter, which then relayed the signal to Earth. Besides acting as a data relay, the orbiter also studied the cloud structure of the planet.
Launch: November 3, 1973
Venus flyby and gravity assist: February 5, 1974
Mariner 10 flew by Venus for a gravity assist on its way to Mercury. It flew within 4,200 kilometers (2,600 miles) of Venus and took the first ultraviolet images of the planet.
Upon Venus arrival Venera 8 used aerobraking to decelerate, and then deployed a parachute. A refrigeration unit cooled the spacecraft's components, protecting them from the intense heat as the lander descended to the surface. Once on the ground, the spacecraft transmitted data for 50 minutes, confirming a very high surface temperature and crushing atmospheric pressure. It also measured the light level on Venus’ surface and found it suitable for surface photography, setting the stage for the images to be returned by Venera 9, 10, 13, and 14.
When Venera 7 arrived it deployed a parachute and began its descent to the surface. Scheduled to take 60 minutes to descend, the probe touched down in only 35 minutes, possibly because its parachute may have been damaged by high winds. The spacecraft then transmitted a weak signal for 23 minutes, becoming the first spacecraft to return data from the surface of another planet. It reported surface temperatures of 475°C and atmospheric pressures 90 times greater than Earth's.
Twin to Venera 5, Venera 6 arrived just a day after its sister ship. Once at Venus, the spacecraft deployed a parachute and descended through the atmosphere. Scientists on Earth received 51 minutes of data as the probe descended 38 kilometers (almost 24 miles). The spacecraft was damaged the crushing pressure before it reached the surface.
Mariner 5 flew within 4,000 kilometers (2,400 miles) of the Venusian cloud tops. During its flyby, the spacecraft measured a surface temperature of 267°C.
When Venera 4 arrived at Venus it dropped several instruments, including a thermometer and a barometer, into the atmosphere. It received data back from these probes before it deployed a parachute and descended into the atmosphere itself. Preliminary readings seemed to indicate that the probe had taken measurements all the way down to the surface, but later analysis suggested that the crushing atmosphere damaged the spacecraft at an altitude of almost 25 kilometers. The probe revealed an atmosphere made almost entirely of carbon dioxide, with temperatures ranging from 40°C high up in the atmosphere to 280°C closer to the surface, and pressures ranging from 15 to 22 atmospheres.
The final stage of the rocket carrying the spacecraft into orbit failed and it was unable to achieve the necessary trajectory to carry it on to Venus.
Mariner 2 was the first spacecraft to successfully fly by Venus, at an altitude of 34,773 kilometers. The spacecraft discovered ground temperatures as high as 428°C (800°F). Other instruments detected no water vapor in the atmosphere or any evidence of a magnetic field around the planet. Radio contact was lost on January 3, 1963.
NASA's Mariner 1 veered off course after launch and had to be destroyed by ground controllers.