RESEARCH STARTER

Venus's surface experiments

Venus's surface experiments have provided critical insights into the planet's geology and soil composition, despite the challenges posed by its dense atmosphere. Early exploration by Soviet spacecraft in the 1970s, particularly the Venera series, marked significant milestones, as they successfully landed on Venus and transmitted valuable data back to Earth. These missions revealed that the soils on Venus are primarily igneous in nature, with a chemical composition similar to basalt and granite found on Earth. For example, Venera 8 discovered volcanic soils, while subsequent landers like Venera 9 and 10 provided images showing various rock types with minimal erosion, which was unexpected given Venus’s extreme conditions.

Further experiments by Venera 13 and 14 explored the rocks in more detail, hinting at possible sedimentary processes despite the absence of water on the planet. The analysis from these missions suggested that Venus may still be geologically active, as indicated by the presence of sulfur and other volcanic elements. Additional missions, including ESA's Venus Express and Japan’s Akatsuki, have continued to contribute to our understanding of Venus's surface and atmosphere. Collectively, these studies have not only enhanced knowledge of Venus itself but have also provided a comparative framework to understand Earth’s geological history and future.

Full Article

An understanding of the geology of the other planets in the solar system is important for understanding the geologic past and future of Earth. Venus holds many clues to this understanding, including its surface geology, which appears to be mostly igneous and basaltic in nature.

Overview

The planet Venus is considered one of the terrestrial, or Earth-like, planets because of its position in the solar system, its planetary diameter, its geology, and other characteristics. Despite being called Earth’s twin because of those similarities, Venus is actually very different. The study of the planet Venus has been, at best, difficult because of its heavy cloud cover.

The best information on the Venusian surface and its soils came early from the Soviets, who focused on exploring the planet, successfully landing six spacecraft on the surface. Even though these craft operated for only limited amounts of time because of the planet’s extreme temperatures and the pressure of its atmosphere, the data provided by them have given astronomers and geologists important clues about the soils on Venus. Much of the information obtained by the Soviets can be compared with that known about Earth and to the data obtained from firsthand examination of the lunar rocks and soils. For example, photographs can be useful in examining the appearance of the soil, rocks, and their distribution. Images taken by Venusian landers can be compared with photographs of similar materials found on Earth and the Moon.

Venera 8 was one of the early Soviet landers to provide clues to the Venusian soils; however, the first successful soft landing on Venus was achieved earlier by Venera 7 in 1970. Venera 8 landed on July 22, 1972, in a region generally thought to be like the rolling plains of Earth. The probe analyzed the surface and soils directly underneath it with a gamma-ray spectrometer designed to determine the chemical composition of surface material. Results showed that the soils under the Venera 8 were igneous, or volcanic, in origin. The layer was found to be approximately 4 percent potassium, approximately 200 parts per million uranium, and approximately 650 parts per million thorium. The layer was also determined to have a density of approximately 1.5 grams per cubic centimeter (0.05 ounces per cubic inch) (in comparison, water has a density of one gram per cubic centimeter at a temperature of 277 kelvins [3.8 degrees Celsius; 39 Fahrenheit]). From these data, astronomers and geologists were able to ascertain not only that the soils under Venera 8 were igneous but also that they were probably similar to the granites or basalts found on Earth.

In 1975, Venera 9 and 10 provided an even better look at the Venusian soils. Each lander transmitted an image that showed the soil and rocks surrounding it. These photographs revealed rocks that were, on average, 20 centimeters (8 inches) wide, about 50 to 60 centimeters (20 to 24 inches) long, and slablike in appearance. A few of the rocks showed evidence of volcanic origin. Many of the rocks had jagged edges, which demonstrates little erosion, although some did show signs of weathering. This relative lack of erosion surprised many astronomers and geologists. They had believed that, because of the planet’s extremes in temperature, atmospheric pressure, wind velocity, and chemical composition, the photographs would show well-eroded landscapes. Astronomer Carl Sagan, among others, hypothesized that low wind velocities at the surface levels of Venus produce little effect on the rock. Apparently, the Venusian surface temperature stays fairly constant and thus does not create much wind. Chemical analysis of the rocks again showed the elements potassium, uranium, and thorium. Nevertheless, the sites differed in the type of rock material. At one Venera lander site, the rocks were basaltic in appearance, similar to those lining Earth’s oceans. At the other site, the rocks were more like granite, similar to that found in Earth’s mountains. The rocks appear to be relatively young in age. This would indicate that the planet has been geologically active in the geologically recent past. The Venusian soil in the areas observed photographically appeared to be loose, coarse-grained dirt. It was also evident from the photographs that Venus (or at least parts of it) is a dry and dusty planet. Radar images from other Venera missions, as well as Pioneer Venus and the Magellan spacecraft, verified this for the rest of the planet.

The Soviets continued their studies of the Venusian surface with two additional spacecraft, Venera 13 and 14. These two spacecraft performed similar examinations but in a much more complex manner. Rather than single images, near-panoramic views of the landing sites were produced. Photographs showed rocks somewhat similar to those found at the Venera 9 and 10 landing sites. Rocks also showed evidence, however, of what appears to be thin layering, ripple marks, and fracturing, especially around Venera 14. Some rocks showed evidence of erosion. On Earth, rocks that show layering—such as sandstone and limestone—are usually sedimentary. Based on the photographs and measurements made by the spacecraft, several Soviet scientists suggested that the Venusian rocks might be sedimentary, but that has not been confirmed.

The possible cause or causes of the erosion remain unknown. In the absence of water, several possibilities have been suggested. These include chemical weathering or erosion caused by nearby volcanism and its resulting ash, dust, and lava. Chemical weathering seems the most likely explanation. Venus’s thick atmosphere has cloud layers laced with sulfuric acid, which rains down as a caustic, corrosive agent on the surface.

Both spacecraft collected a cubic centimeter of Venusian soil for analysis. The probes utilized an X-ray source to stimulate emissions from the collected soil samples. This chemical analysis revealed that the samples were similar to basalt in composition, although the basalts differed at the two sites. Near the Venera 13 landing site, the type of basalt found is referred to as leucitic high-potassium basalt, while near the Venera 14 landing site, a tholeiitic basalt, similar to that found on the ocean floors on Earth, was found. The soil itself appeared fine-grained, and the photographs revealed many small rocks. It has been speculated that this also indicates that weathering processes of some type are at work, breaking down larger rocks into smaller ones, eventually reducing them to soil.

Another pair of Soviet probes, the Vega 1 and 2 spacecraft, landed on Venus in June 1985. Vega 2 results revealed a Venusian soil and surface that are again similar to basalt. Nevertheless, the new data also revealed a surface rich in the element sulfur, which is usually associated with volcanism. This presence has provided another clue to the surface and geology of Venus.

Venera 8 landed about 5,000 kilometers (3,100 miles) east of an area referred to as the Phoebe region. Venera 9, 10, 13, and 14 all landed between 900 and 3,000 kilometers (560 and 1,860 miles) east of the raised areas known as Beta Regio and Phoebe Regio. Even though the craft landed on and took samples from an area that could be of the same or similar geologic makeup, they have given astronomers and geologists a good idea of the planet’s surface composition.

The probes produced mostly photographic data, although some chemical analysis was conducted on-site. Thus, any discussion of soil samples is based on the evidence reported by these spacecraft since no samples have ever been returned to Earth for detailed study. Spacecraft data have enabled astronomers and geologists to begin to understand not only the surface of the planet Venus and its chemical makeup but also the planet’s evolutionary path. Scientists continued to collect data about Venus in the twenty-first century. The Akatsuki spacecraft entered Venus’s orbit in 2015 after being launched in 2010, and the Parker Solar Probe, launched in 2018, and the Solar Orbiter, launched in 2020, both made multiple fly-bys of the planet.

Knowledge Gained

It appears that Venus may still be an active planet geologically, which scientists inferred from the discovery of high concentrations of sulfur in Venus’s atmosphere. Thus, its soils, for the most part, must be considered with that fact in mind.

Analysis of Venusian rocks around the landers provided scientists with interesting but sometimes confusing data. For example, the fact that most of the rocks appear to lack signs of erosion at first seemed puzzling. An understanding of the weather patterns on Venus and the planet’s atmospheric chemistry, however, has led to the development of theories relating the small-scale erosion to a low wind velocity at the surface because of its virtually uniform temperature. The rocks themselves appeared to be mostly igneous in nature. Most igneous samples appeared to be similar to basalt, much like those rocks and materials that line Earth’s ocean floors. Some of the rocks resembled granite, like those that form Earth’s mountains. However, despite apparent volcanic origins for Venus’s crust, some specimens appeared to be sedimentary. This led to further questions which remain unanswered. Although the sedimentation process on Earth is usually accomplished by water, present-day Venus has no water, nor is there any evidence of water in its near past. The origins of this phenomenon remain unknown.

Analyzed samples varied slightly from site to site, as was expected by geologists, since samples on Earth also differ. In fact, the variation of Earth samples is greater than that of the limited Venusian ones. Nevertheless, potassium—a key element in igneous and especially basaltic materials—was detected, as were uranium and thorium. Geologically, the rocks are relatively young, presenting additional evidence that Venus is a planet that may be experiencing continuous changes. Fine-grained soils were found at some sites, while coarser soils appeared at others. At one site, at least, smaller rocks led scientists to theorize that erosion does occur on the planet, thus producing soil.

Context

When the planets of the solar system are categorized, one usually finds two major groupings: the terrestrial or Earth-like planets and the Jovian or Jupiter-like planets (sometimes also called the gas giants). Venus, because of its relative size, atmosphere, position within the solar system, and surface, is naturally among the set of terrestrial planets: Mercury, Venus, Earth, and Mars.

An understanding of the nature of the terrestrial planets, their atmospheres, planetary geologies, and soils can give astronomers and geologists clues to the pasts not only of these worlds but also of the Earth—revealing how these planets were formed, what geological changes they have undergone, and how they might be related. Venus holds many clues to the formation of the solar system. Unfortunately, observations of the Venusian surface are nearly impossible because of the dense atmosphere that surrounds the planet. Orbiting spacecraft provide information regarding the general geologic contours on the surface—the planet’s mountains, valleys, craters, and other surface features—but hard evidence of the nature of the surface, particularly its soil, can come only from the surface of the planet. Prior to the landing of Soviet probes, no information about the Venusian surface existed.

Materials sampled and photographed in the vicinities of the Soviet landers proved to be mostly igneous in nature. Additional on-site chemical analysis showed these materials—both rocks and soils—to be similar to granite or basalt. Basalt-type materials are not unique to the second planet from the Sun. These materials have been found on Mars in the vicinities of the American Viking landers, in samples brought back from the Moon by the American Apollo crews, and by uncrewed Soviet spacecraft. As Soviet spacecraft became more sophisticated and knowledge of the harsh Venusian environment grew, landers were able to provide data on the surface of Venus, among other things. Additional information may provide scientists with clues to the past of the terrestrial planets, part of which is hidden in the Venusian surface and soil. Perhaps more important, Venusian soil information may provide clues to Earth’s future, particularly regarding the Earth’s fragile environment.

Comparative planetology is essential for achieving a more complete understanding of the Earth. As Venus, Earth, and Mars started out relatively similar in the early solar system, and all three are in the habitable zone, why is it then that Venus is devoid of water and hot with a thick atmosphere of carbon dioxide, Earth is capable of supporting life, and Mars has no liquid surface water and is cold, with a thin atmosphere of carbon dioxide? Only when that question is answered will scientists have a clear idea of Earth’s complex planetary environment.

Work performed along the way to that understanding has included spacecraft dispatched to the veiled planet Venus by both the Soviet Union and the United States. American spacecraft have only flown by Venus or studied it from orbit. The Japanese Aerospace Exploration Agency and the European Space Agency have also produced orbiters that have either orbited the planet or made fly-bys. The National Aeronautics and Space Administration (NASA) has had more interest in exploring Mars than Venus. However, because the Soviets have had only bad luck when it comes to Martian exploration, they have emphasized the study of Venus with flyby craft, landers, orbiters, and even balloons temporarily floating within its hellish atmosphere. NASA announced plans to return to the study of Venus in the 2020s through the launch of two robotic probes, the DAVINCI+, a probe that will fall into the planet’s atmosphere, and the VERITAS, which will enter orbit around Venus. In the meantime, the European Space Agency’s (ESA) Venus Express began orbiting Venus on April 11, 2006, conducting mapping operations and other scientific investigations of Venus’s surface and atmosphere. In October 2012, the ESA agreed to continue funding the orbiter through December 2014.

The Japanese spacecraft Akatsuki, also known as the Venus Climate Orbiter, began orbiting Venus in 2015 as Japan's first spacecraft to orbit a planet other than Earth. During its mission, it mapped clouds and atmospheric constituents, detected lightning, and observed the structure and gravity waves in Venus’s atmosphere. However, in April 2024, Japan announced they had lost contact with Akatsuki but were attempting to reestablish operations.

The Parker Solar Probe made its first flyby of Venus on October 3, 2018, and on November 6, 2024, it completed its seventh and, according to NASA’s prediction, final flyby of the planet. On its final flyby, it came within about 385 kilometers (240 miles) of Venus’s surface. During its mission, the probe gathered many important pieces of information about the planet. During its third and fourth flybys, it captured the first visible-light images taken from space of Venus' nightside surface, revealing plateaus and other features previously not visible because of cloud coverage.

A 2026 budget shortfall is impacting several missions focused on surface mapping and geology, including the VERITAS mission and the EnVision mission. NASA may reduce its contributions—such as the VenSAR radar—potentially transferring more of the responsibility to ESA.


Bibliography

Cattermole, Peter John. Venus: The Geological Story. Johns Hopkins UP, 1996.

Corliss, William R., editor. The Moon and the Planets. Sourcebook Project, 1985.

“DAVINCI.” NASA Science, National Aeronautics and Space Administration, 3 Mar. 2026, science.nasa.gov/mission/davinci/. Accessed 6 May 2026.

Esposito, Larry W., et al., editors. Exploring Venus as a Terrestrial Planet. American Geophysical Union, 2007.

Fimmel, Richard O., et al. Pioneering Venus: A Planet Unveiled. National Aeronautics and Space Administration, 1995.

Foust, Jeff. “NASA Grappling with Planetary Science Funding Shortfall.” SpaceNews, 18 Mar. 2026, spacenews.com/nasa-grappling-with-planetary-science-funding-shortfall/. Accessed 6 May 2026.

Frazier, Kendrick. Solar Systems. Rev. ed., Time-Life Books, 1985.

Garvin, James B., et al. “DAVINCI MISSION TO VENUS’ ATMOSPHERE AND SURFACE: SCIENCE UPDATE 2026.” Lunar and Planetary Science Conference 2026, NASA Goddard Space Flight Center, Greenbelt, MD, 2026, www.hou.usra.edu/meetings/lpsc2026/pdf/1685.pdf. Accessed 6 May 2026.

Grinspoon, David Harry. Venus Revealed: A New Look below the Clouds of Our Mysterious Twin Planet. Basic Books, 1998.

Hartmann, William K. Moons and Planets. 5th ed., Thomson Brooks/Cole, 2005.

Howell, Elizabeth. “Russia Aims to Reclaim Soviet Space Glory with 2036 Launch of Ambitious Venus Mission.” Space.com, 14 Mar. 2026, www.space.com/astronomy/venus/russia-aims-to-reclaim-soviet-space-glory-with-2036-launch-of-ambitious-venus-mission. Accessed 6 May 2026.

Ksanfomality, L. V. “Abundance of Unusual Objects on the Planet Venus According to the Data of Missions of 1975–1982.” Cosmic Research, vol. 52, no. 6, 2014, pp. 430–36, doi:10.1134/S0010952514040066. Accessed 6 May 2026.

Ksanfomality, L. V. “Results of the New Processing of Images Obtained from the Surface of Venus in a TV Experiment Onboard the VENERA-9 Lander (1975).” Solar System Research, vol. 46, no. 5, 2012, pp. 364–73, doi:10.1134/S0038094612050061. Accessed 6 May 2026.

Kuthunur, Sharmila. “NASA’s Ambitious ‘Decade of Venus’ Exploration May Bank on 1 Probe: ‘Not Everything Can Move Forward.’” Space.com, 27 Mar. 2026, www.space.com/space-exploration/missions/nasas-ambitious-decade-of-venus-exploration-may-bank-on-1-probe-not-everything-can-move-forward. Accessed 6 May 2026.

Morrison, David, and Tobias Owen. The Planetary System. 3rd ed., Pearson/Addison-Wesley, 2003.

Sheehan, William, and Klaus Brasch. The Space Age Generation: Lives and Lessons from the Golden Age of Solar System Exploration. U of Arizona P, 2024.

Snow, Theodore P. The Dynamic Universe. Rev. ed., West, 1991.

“Venus Atmosphere and Cloud Particle Sample Return for Astrobiology.” NASA, 26 July 2023, www.nasa.gov/directorates/spacetech/niac/2022/Venus_Atmosphere_and_Cloud_Particle_Sample_Return_for_Astrobiology. Accessed 6 May 2026.

“Venus Facts.” NASA Science, 31 Mar. 2026, science.nasa.gov/venus/venus-facts/. Accessed 6 May 2026.

“Venus—Venera 8 Landing Site in Navka Region.” NASA, 26 Sept. 1996, science.nasa.gov/photojournal/venus-venera-8-landing-site-in-navka-region/. Accessed 6 May 2026.

Zastrow, Mark. “NASA to Return to Venus with Two Missions by 2030.” Astronomy Magazine, 18 May 2023, www.astronomy.com/science/nasa-to-return-to-venus-with-two-missions-by-2030. Accessed 6 May 2026.

Full Article

An understanding of the geology of the other planets in the solar system is important for understanding the geologic past and future of Earth. Venus holds many clues to this understanding, including its surface geology, which appears to be mostly igneous and basaltic in nature.

Overview

The planet Venus is considered one of the terrestrial, or Earth-like, planets because of its position in the solar system, its planetary diameter, its geology, and other characteristics. Despite being called Earth’s twin because of those similarities, Venus is actually very different. The study of the planet Venus has been, at best, difficult because of its heavy cloud cover.

The best information on the Venusian surface and its soils came early from the Soviets, who focused on exploring the planet, successfully landing six spacecraft on the surface. Even though these craft operated for only limited amounts of time because of the planet’s extreme temperatures and the pressure of its atmosphere, the data provided by them have given astronomers and geologists important clues about the soils on Venus. Much of the information obtained by the Soviets can be compared with that known about Earth and to the data obtained from firsthand examination of the lunar rocks and soils. For example, photographs can be useful in examining the appearance of the soil, rocks, and their distribution. Images taken by Venusian landers can be compared with photographs of similar materials found on Earth and the Moon.

Venera 8 was one of the early Soviet landers to provide clues to the Venusian soils; however, the first successful soft landing on Venus was achieved earlier by Venera 7 in 1970. Venera 8 landed on July 22, 1972, in a region generally thought to be like the rolling plains of Earth. The probe analyzed the surface and soils directly underneath it with a gamma-ray spectrometer designed to determine the chemical composition of surface material. Results showed that the soils under the Venera 8 were igneous, or volcanic, in origin. The layer was found to be approximately 4 percent potassium, approximately 200 parts per million uranium, and approximately 650 parts per million thorium. The layer was also determined to have a density of approximately 1.5 grams per cubic centimeter (0.05 ounces per cubic inch) (in comparison, water has a density of one gram per cubic centimeter at a temperature of 277 kelvins [3.8 degrees Celsius; 39 Fahrenheit]). From these data, astronomers and geologists were able to ascertain not only that the soils under Venera 8 were igneous but also that they were probably similar to the granites or basalts found on Earth.

In 1975, Venera 9 and 10 provided an even better look at the Venusian soils. Each lander transmitted an image that showed the soil and rocks surrounding it. These photographs revealed rocks that were, on average, 20 centimeters (8 inches) wide, about 50 to 60 centimeters (20 to 24 inches) long, and slablike in appearance. A few of the rocks showed evidence of volcanic origin. Many of the rocks had jagged edges, which demonstrates little erosion, although some did show signs of weathering. This relative lack of erosion surprised many astronomers and geologists. They had believed that, because of the planet’s extremes in temperature, atmospheric pressure, wind velocity, and chemical composition, the photographs would show well-eroded landscapes. Astronomer Carl Sagan, among others, hypothesized that low wind velocities at the surface levels of Venus produce little effect on the rock. Apparently, the Venusian surface temperature stays fairly constant and thus does not create much wind. Chemical analysis of the rocks again showed the elements potassium, uranium, and thorium. Nevertheless, the sites differed in the type of rock material. At one Venera lander site, the rocks were basaltic in appearance, similar to those lining Earth’s oceans. At the other site, the rocks were more like granite, similar to that found in Earth’s mountains. The rocks appear to be relatively young in age. This would indicate that the planet has been geologically active in the geologically recent past. The Venusian soil in the areas observed photographically appeared to be loose, coarse-grained dirt. It was also evident from the photographs that Venus (or at least parts of it) is a dry and dusty planet. Radar images from other Venera missions, as well as Pioneer Venus and the Magellan spacecraft, verified this for the rest of the planet.

The Soviets continued their studies of the Venusian surface with two additional spacecraft, Venera 13 and 14. These two spacecraft performed similar examinations but in a much more complex manner. Rather than single images, near-panoramic views of the landing sites were produced. Photographs showed rocks somewhat similar to those found at the Venera 9 and 10 landing sites. Rocks also showed evidence, however, of what appears to be thin layering, ripple marks, and fracturing, especially around Venera 14. Some rocks showed evidence of erosion. On Earth, rocks that show layering—such as sandstone and limestone—are usually sedimentary. Based on the photographs and measurements made by the spacecraft, several Soviet scientists suggested that the Venusian rocks might be sedimentary, but that has not been confirmed.

The possible cause or causes of the erosion remain unknown. In the absence of water, several possibilities have been suggested. These include chemical weathering or erosion caused by nearby volcanism and its resulting ash, dust, and lava. Chemical weathering seems the most likely explanation. Venus’s thick atmosphere has cloud layers laced with sulfuric acid, which rains down as a caustic, corrosive agent on the surface.

Both spacecraft collected a cubic centimeter of Venusian soil for analysis. The probes utilized an X-ray source to stimulate emissions from the collected soil samples. This chemical analysis revealed that the samples were similar to basalt in composition, although the basalts differed at the two sites. Near the Venera 13 landing site, the type of basalt found is referred to as leucitic high-potassium basalt, while near the Venera 14 landing site, a tholeiitic basalt, similar to that found on the ocean floors on Earth, was found. The soil itself appeared fine-grained, and the photographs revealed many small rocks. It has been speculated that this also indicates that weathering processes of some type are at work, breaking down larger rocks into smaller ones, eventually reducing them to soil.

Another pair of Soviet probes, the Vega 1 and 2 spacecraft, landed on Venus in June 1985. Vega 2 results revealed a Venusian soil and surface that are again similar to basalt. Nevertheless, the new data also revealed a surface rich in the element sulfur, which is usually associated with volcanism. This presence has provided another clue to the surface and geology of Venus.

Venera 8 landed about 5,000 kilometers (3,100 miles) east of an area referred to as the Phoebe region. Venera 9, 10, 13, and 14 all landed between 900 and 3,000 kilometers (560 and 1,860 miles) east of the raised areas known as Beta Regio and Phoebe Regio. Even though the craft landed on and took samples from an area that could be of the same or similar geologic makeup, they have given astronomers and geologists a good idea of the planet’s surface composition.

The probes produced mostly photographic data, although some chemical analysis was conducted on-site. Thus, any discussion of soil samples is based on the evidence reported by these spacecraft since no samples have ever been returned to Earth for detailed study. Spacecraft data have enabled astronomers and geologists to begin to understand not only the surface of the planet Venus and its chemical makeup but also the planet’s evolutionary path. Scientists continued to collect data about Venus in the twenty-first century. The Akatsuki spacecraft entered Venus’s orbit in 2015 after being launched in 2010, and the Parker Solar Probe, launched in 2018, and the Solar Orbiter, launched in 2020, both made multiple fly-bys of the planet.

Knowledge Gained

It appears that Venus may still be an active planet geologically, which scientists inferred from the discovery of high concentrations of sulfur in Venus’s atmosphere. Thus, its soils, for the most part, must be considered with that fact in mind.

Analysis of Venusian rocks around the landers provided scientists with interesting but sometimes confusing data. For example, the fact that most of the rocks appear to lack signs of erosion at first seemed puzzling. An understanding of the weather patterns on Venus and the planet’s atmospheric chemistry, however, has led to the development of theories relating the small-scale erosion to a low wind velocity at the surface because of its virtually uniform temperature. The rocks themselves appeared to be mostly igneous in nature. Most igneous samples appeared to be similar to basalt, much like those rocks and materials that line Earth’s ocean floors. Some of the rocks resembled granite, like those that form Earth’s mountains. However, despite apparent volcanic origins for Venus’s crust, some specimens appeared to be sedimentary. This led to further questions which remain unanswered. Although the sedimentation process on Earth is usually accomplished by water, present-day Venus has no water, nor is there any evidence of water in its near past. The origins of this phenomenon remain unknown.

Analyzed samples varied slightly from site to site, as was expected by geologists, since samples on Earth also differ. In fact, the variation of Earth samples is greater than that of the limited Venusian ones. Nevertheless, potassium—a key element in igneous and especially basaltic materials—was detected, as were uranium and thorium. Geologically, the rocks are relatively young, presenting additional evidence that Venus is a planet that may be experiencing continuous changes. Fine-grained soils were found at some sites, while coarser soils appeared at others. At one site, at least, smaller rocks led scientists to theorize that erosion does occur on the planet, thus producing soil.

Context

When the planets of the solar system are categorized, one usually finds two major groupings: the terrestrial or Earth-like planets and the Jovian or Jupiter-like planets (sometimes also called the gas giants). Venus, because of its relative size, atmosphere, position within the solar system, and surface, is naturally among the set of terrestrial planets: Mercury, Venus, Earth, and Mars.

An understanding of the nature of the terrestrial planets, their atmospheres, planetary geologies, and soils can give astronomers and geologists clues to the pasts not only of these worlds but also of the Earth—revealing how these planets were formed, what geological changes they have undergone, and how they might be related. Venus holds many clues to the formation of the solar system. Unfortunately, observations of the Venusian surface are nearly impossible because of the dense atmosphere that surrounds the planet. Orbiting spacecraft provide information regarding the general geologic contours on the surface—the planet’s mountains, valleys, craters, and other surface features—but hard evidence of the nature of the surface, particularly its soil, can come only from the surface of the planet. Prior to the landing of Soviet probes, no information about the Venusian surface existed.

Materials sampled and photographed in the vicinities of the Soviet landers proved to be mostly igneous in nature. Additional on-site chemical analysis showed these materials—both rocks and soils—to be similar to granite or basalt. Basalt-type materials are not unique to the second planet from the Sun. These materials have been found on Mars in the vicinities of the American Viking landers, in samples brought back from the Moon by the American Apollo crews, and by uncrewed Soviet spacecraft. As Soviet spacecraft became more sophisticated and knowledge of the harsh Venusian environment grew, landers were able to provide data on the surface of Venus, among other things. Additional information may provide scientists with clues to the past of the terrestrial planets, part of which is hidden in the Venusian surface and soil. Perhaps more important, Venusian soil information may provide clues to Earth’s future, particularly regarding the Earth’s fragile environment.

Comparative planetology is essential for achieving a more complete understanding of the Earth. As Venus, Earth, and Mars started out relatively similar in the early solar system, and all three are in the habitable zone, why is it then that Venus is devoid of water and hot with a thick atmosphere of carbon dioxide, Earth is capable of supporting life, and Mars has no liquid surface water and is cold, with a thin atmosphere of carbon dioxide? Only when that question is answered will scientists have a clear idea of Earth’s complex planetary environment.

Work performed along the way to that understanding has included spacecraft dispatched to the veiled planet Venus by both the Soviet Union and the United States. American spacecraft have only flown by Venus or studied it from orbit. The Japanese Aerospace Exploration Agency and the European Space Agency have also produced orbiters that have either orbited the planet or made fly-bys. The National Aeronautics and Space Administration (NASA) has had more interest in exploring Mars than Venus. However, because the Soviets have had only bad luck when it comes to Martian exploration, they have emphasized the study of Venus with flyby craft, landers, orbiters, and even balloons temporarily floating within its hellish atmosphere. NASA announced plans to return to the study of Venus in the 2020s through the launch of two robotic probes, the DAVINCI+, a probe that will fall into the planet’s atmosphere, and the VERITAS, which will enter orbit around Venus. In the meantime, the European Space Agency’s (ESA) Venus Express began orbiting Venus on April 11, 2006, conducting mapping operations and other scientific investigations of Venus’s surface and atmosphere. In October 2012, the ESA agreed to continue funding the orbiter through December 2014.

The Japanese spacecraft Akatsuki, also known as the Venus Climate Orbiter, began orbiting Venus in 2015 as Japan's first spacecraft to orbit a planet other than Earth. During its mission, it mapped clouds and atmospheric constituents, detected lightning, and observed the structure and gravity waves in Venus’s atmosphere. However, in April 2024, Japan announced they had lost contact with Akatsuki but were attempting to reestablish operations.

The Parker Solar Probe made its first flyby of Venus on October 3, 2018, and on November 6, 2024, it completed its seventh and, according to NASA’s prediction, final flyby of the planet. On its final flyby, it came within about 385 kilometers (240 miles) of Venus’s surface. During its mission, the probe gathered many important pieces of information about the planet. During its third and fourth flybys, it captured the first visible-light images taken from space of Venus' nightside surface, revealing plateaus and other features previously not visible because of cloud coverage.

A 2026 budget shortfall is impacting several missions focused on surface mapping and geology, including the VERITAS mission and the EnVision mission. NASA may reduce its contributions—such as the VenSAR radar—potentially transferring more of the responsibility to ESA.


Bibliography

Cattermole, Peter John. Venus: The Geological Story. Johns Hopkins UP, 1996.

Corliss, William R., editor. The Moon and the Planets. Sourcebook Project, 1985.

“DAVINCI.” NASA Science, National Aeronautics and Space Administration, 3 Mar. 2026, science.nasa.gov/mission/davinci/. Accessed 6 May 2026.

Esposito, Larry W., et al., editors. Exploring Venus as a Terrestrial Planet. American Geophysical Union, 2007.

Fimmel, Richard O., et al. Pioneering Venus: A Planet Unveiled. National Aeronautics and Space Administration, 1995.

Foust, Jeff. “NASA Grappling with Planetary Science Funding Shortfall.” SpaceNews, 18 Mar. 2026, spacenews.com/nasa-grappling-with-planetary-science-funding-shortfall/. Accessed 6 May 2026.

Frazier, Kendrick. Solar Systems. Rev. ed., Time-Life Books, 1985.

Garvin, James B., et al. “DAVINCI MISSION TO VENUS’ ATMOSPHERE AND SURFACE: SCIENCE UPDATE 2026.” Lunar and Planetary Science Conference 2026, NASA Goddard Space Flight Center, Greenbelt, MD, 2026, www.hou.usra.edu/meetings/lpsc2026/pdf/1685.pdf. Accessed 6 May 2026.

Grinspoon, David Harry. Venus Revealed: A New Look below the Clouds of Our Mysterious Twin Planet. Basic Books, 1998.

Hartmann, William K. Moons and Planets. 5th ed., Thomson Brooks/Cole, 2005.

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