Shrouded in thick clouds, our erstwhile sister planet Venus is rife with mysteries. Among the Solar System’s rocky planets, Venus is the one begging for more exploration. While potential habitability always catches people’s attention, scientists crave more fundamental knowledge about Venus: its geology.
Universe Today readers likely know that only a small handful of spacecraft have ever reached Venus’ surface. During the 70s and 80s, the USSR sent multiple spacecraft to Venus. Most of them succumbed to the planet’s harsh conditions in minutes, with the longest lasting only two hours.
As a result, scientists have only limited in-situ measurements of the planet’s geology. A new mission concept called Valkyrie aims to bolster our knowledge. “VALKYRIE: A MISSION TO THE VENUS SURFACE,” was presented at the 2025 Lunar and Planetary Science Conference in Texas. The authors are A. R. Santos from the Department of Earth and Environmental Sciences at Wesleyan University, and A. M. Parsons from NASA’s Goddard Space Flight Center.
Venus and Earth are very similar in size and mass. As rocky planets in the inner Solar System, they likely formed from similar materials. They have similar structures, with a core, a mantle, and a crust. However, the similarities seem to end there.
The pair of planets have wildly different atmospheres. While Earth’s atmosphere is dominated by nitrogen (78%) and oxygen (21%), Venus is dominated by carbon dioxide (96.5%). Earth’s atmosphere helps moderate the planet’s temperature and allows liquid water to persist on the surface, while Venus is more like hell than Earth. Its blistering temperatures and extreme atmospheric pressure are destructive. That’s why the Soviet landers lasted for such a short time.
The Soviet Union’s Venera 13 probe captured two colour panoramas of Venus’s surface in 1982. This panorama came from the rear camera. Image Credit: Russian Academy of Sciences / Ted Stryk
These differences are begging for deeper investigation. Geology is at the heart of these differences, and the Valkyrie mission proposal is aimed at geology.
“There currently are only three analyses of Venus rocks that provide major element chemistry, and five measurements of the naturally radioactive elements K, U, Th, all of which were provided by the 1970s-1980s era Venera and Vega missions from the USSR,” the authors write. “These analyses, while technological marvels of their time, have large error bars (e.g., Mg) and are missing elements key to igneous petrology, such as Na and P, rendering them of limited usefulness to current petrologic techniques.”
The authors also point out that the technology available decades ago led to poorly constrained landing sites. There was no way to target the landers at specific sites.
“The Valkyrie mission concept aims to fill the dearth of data from Venus rocks, allowing significant advances in the understanding of the planet and its evolution and helping address the question: were Venus and Earth different from the start?,” the authors write.
The Valkyrie concept isn’t complicated. It would consist of an orbiter that launches multiple identical landers to different locations on Venus’ surface, chosen because they represent different geological conditions. A constellation of small satellites and the orbiter would relay information back to Earth. The landers would carry the same payload: descent cameras, panoramic cameras, and gamma-ray spectrometers (GRS) with pulsed neutron generators (PNGs).
This simple cartoon shows small landers deployed to the surface of Venus communicating with small satellites and an orbiter, which then relay information back to Earth. Image Credit: Santos and Parsons 2025.
This level of technology wasn’t available when the Venera and Vega probes were sent to Venus. Some of the older probes carried similar technologies; for example, Venera 8 carried a GRS. But five decades have passed since then, and technology has advanced a lot.
One of the main differences between Valkyrie and previous probes concerns atmospheric pressure. When the Venera program began, scientists didn’t know that Venus’ atmospheric pressure was so high, which led to underbuilt probes. Now that we know Venus’ atmosphere is so highly pressurized, we can prepare for it.
The Valkyrie landers will have a pressure vessel with thermal controls to protect the instruments and allow them to function. “The landers will consist of a pressure vessel with thermal control elements, as this instrument suite cannot operate at ambient Venus conditions. These instruments allow regional context imaging of each landing site during descent, local landing site imaging once on the ground, and measurement of major, minor, and trace element chemistry of a bulk portion of rock beneath the lander,” the authors write.
Both neutrons and gamma rays can penetrate the vessel, meaning the instruments can be sealed off from the environment while still functioning. There’s no need for an opening of any kind, which simplifies the lander’s design. Plus, the instruments don’t need to be aimed, adding to the simplicity.
The Valkyrie landers would contain their instruments inside a pressure vessel for protection. Since the instruments are omnidirectional, there’s no need to aim them. There’s also no need for any openings. Image Credit: Santos and Parsons 2025.
“In addition, GRS are omnidirectional detectors, so if the landers can carry omnidirectional communication arrays, there is little risk associated with needing to keep the landers at specific orientations once on the ground,” the authors explain. The simplicity of design makes it cheaper to build several landers, another key aspect of the mission. “Multiple landers will allow investigation of multiple sites on the planet, allowing Valkyrie to sample from a range of rock types, compositions, and geologic environments.”
Though the Valkyrie landers will be robust enough to resist the pressure, the heat will still get to them. They’ll have a limited lifetime, which is why there are several small satellites rather than a single orbiter. “Due to the temperatures on the Venus surface, the lifetime of each lander will be limited; thus, data must be uploaded quickly and as often as possible from the landers,” Santos and Parsons write.
The Valkyrie landers hope to answer our biggest questions about Venus: when did Venus and Earth diverge in their evolution?
Scientists have pondered this question deeply and come up with different answers. Venus is closer to the Sun, and some think this could’ve had a huge impact on the planet. Some point to Venus’ lack of plate tectonics, which on Earth help regulate the climate and remove carbon from the atmosphere. Some scientists also think that Venus once had water but couldn’t retain it. Venus’ slow rotation compared to Earth could also be a factor, limiting the planet’s ability to generate a magnetic shield.
Valkyrie hopes to understand how the two planets are different by measuring the chemistry of rock at different locations. “By measuring the bulk chemistry of rocks, specifically basalts, from different parts of the planet, Valkyrie will allow reconstruction of the bulk composition of the planet Venus, from major to trace element level, to constrain any bulk chemical differences between Earth and Venus,” the authors explain. Ideally, five sites would be chosen.
When it comes to Mars, we have the good fortune of having its rock delivered to Earth for study in the form of meteorites. Studying these meteorites allowed scientists to determine Mars’ bulk composition from basalt chemistry, and even though rovers have studied Mars more intently, they haven’t changed our understanding of Mars’ bulk chemistry.
Martian meteorites like this one, named ‘Black Beauty,’ allowed scientists to study Mars’ bulk composition long before rovers could confirm it. We know of no meteorites on Earth that came from Venus, so that avenue of research isn’t available. Image Credit: By NASA – Public Domain, https://commons.wikimedia.org/w/index.php?curid=23571238
Unfortunately, we have no meteorites from Venus, so we have to go to Venus to study its bulk chemistry. The study of the Martian meteorites shows that the Valkyrie landers should be able to do the same by studying basalt on Venus.
“Because no meteorites currently in our collection can be linked to Venus, a mission like Valkyrie can obtain the necessary data for this type of calculation. Obtaining compositional information from Venusian basalts will advance several branches of science for Venus, finally allowing the full power of petrology to be applied in the understanding of this planet,” the authors write.
Whatever scientists can learn about Venus’ bulk composition from Valkyrie will tell us more about the Solar System and cosmochemistry in general, not just Venus itself. That knowledge can place “… constraints on the formation of the Solar System, as well as terrestrial planet evolution,” the authors explain.
At present, Valkyrie is just a concept. The authors say that a more formal mission concept study is needed to flesh out the idea. They also say that while they’ve worked with the idea of five surface locations, the mission is easily scalable.
Another benefit concerns the constellation of satellites. The authors say that these can be left in orbit to serve subsequent missions to Venus, which also likely face mission length constraints due to the hostile environment. This mirrors what’s happened at Mars, where long-lived orbiters have worked together with multiple landers and rovers during a long-term effort to understand the red planet.
Valkyrie could lay the groundwork for a long-term plan to study Venus as the Mars Exploration Program does for Mars. It could help scientists determine where to explore next and what questions need answers from which instruments.
Maybe Valkyrie could be the first mission in a series of missions that will unravel the mystery of our sister planet.
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