Under consideration to become the next Discovery Program mission, VERITAS would reveal the inner workings of Earth's mysterious "twin."

Imagine Earth. Now fill the skieswith thick, Sun-obscuring clouds of sulfuric acid; boil off the oceans bycranking up the temperature to 900 degrees Fahrenheit (nearly 500 degreesCelsius), and boost the air pressure high enough to flatten you like a pancake.What you now have is Venus, a rocky planet similar in size to Earth butdifferent in almost every other way.

How these "sister planets"evolved so differently has been a burning scientific question for decades, anda proposed mission called VERITAS seeks to provide answers by transforming ourunderstanding of the internal geodynamics that shaped the planet. The missioncould lend insights into our own planet's evolution and even help us better understandrocky planets orbiting other stars.

Short for Venus Emissivity,Radio Science, InSAR, Topography & Spectroscopy, VERITAS is beingconsidered for selection under NASA'sDiscovery Program and would be managed by NASA's Jet PropulsionLaboratory in Southern California. The project's partners include LockheedMartin, the Italian Space Agency, the German Space Agency, and the French SpaceAgency.

"Venus is like thiscosmic gift of an accident," said Suzanne Smrekar, principal investigatorof VERITAS at JPL. "You have these two planetary bodies - Earth and Venus -that started out nearly the same but have gone down two completely differentevolutionary paths, but we don't know why."

This interactive model compares the sizes of Venus (left) and Earth. To discover more about the similarities and differences of the two planets, zoom in and give them a spin, or use the search function at bottom for more. Credit: NASA/JPL-Caltech. View the full interactive experience at Eyes on the Solar System. Credit: NASA/JPL-Caltech

The last mission to study theplanet's surface, NASA's Magellan spacecraft, ended in 1994. While it providedtantalizing clues about Venus' geology, the instrumentation couldn't providecertitude as to the origin of many of the planet's surface features.

Proposed for a 2026 launch, VERITASwould orbit the planet and peer through the obscuring clouds with a powerful state-of-theart radar system to create 3D global maps and a near-infrared spectrometer to figureout what the surface is made of. It would also measure the planet'sgravitational field to determine the structure of Venus' interior. Together,the instruments would offer clues about the planet's past and present geologicprocesses, from its core to its surface.

AWindow Into Early Earth

Here on Earth, the rigid crustthat envelops the planet is broken into a jigsaw puzzle of tectonic plates atopthe mantle. Convection in the mantle helps drive motion of the surface plates. Assome plates descend into the interior - a process known as subduction - they melt,and volcanic outgassing releases volatiles (such as water, nitrogen, carbondioxide, and methane) into the atmosphere.

Learning more about thegeologic processes on Venus - where the warm crust is a good analogy for earlyEarth's, when the plates were just beginning to form - could offer a valuableglimpse into how these processes beganon Earth.

"The biggest mystery tome is the extent of deformation structures on Venus" - areas of rock onthe surface that have buckled under immense geologic pressure - "that couldbe studied to understand the nature of tectonic activity on the planet,"said science team member Joann Stock, a professor of geology and geophysics atCaltech's Seismological Laboratory in Pasadena.

Producing high-resolution 3Dtopographic maps VERITAS would bring into focus structures that have previouslybeen too small to resolve, added Stock. These structures could include raised topography on both sides of strike-slip faults,like the San Andreas Fault, which is an indicator of major tectonic activity.VERITAS would also look for active surface faulting using something called interferometricdeformation maps for the first time beyond Earth.

In addition, VERITAS wouldstudy vast deformation structures called tessera. These plateau-like featuresmay be analogous to Earth's continents. A leading theory is that Earth's continentsformed when iron-rich oceanic crust subducted and melted in the presence ofwater, producing huge volumes of new, less iron-rich continental crust that roseabove the ocean.

To determine if Venus' tesseraplateaus formed in a similar way to Earth's continents, VERITAS would constructthe first global multispectral maps of Venus' surface composition. If theircomposition resembles that of continental crust, we'd also gain informationabout Venus' wetter past.

AVolcanic World

On Earth, plate tectonics andvolcanism go hand in hand. But what about on Venus?

"Determining whetherVenus is actively undergoing volcanic activity and understanding what processis driving it is one of the really exciting questions I'd love to see answered,"said planetary scientist Jennifer Whitten, a VERITAS science team member atTulane University in New Orleans.

Using its spectrometer, VERITASwould determine which rocks recently formed from erupting magma, before interactionswith the atmosphere have had time to change their chemical composition. Inaddition, the spectrometer would search for hotspots from active eruptions,while the radar instrument would search for active faulting, an indication oftectonic activity.

In getting to know Venus'volcanoes and the geophysical processes causing them, scientists could also gaugetheir impact on the planet's climate and, perhaps, answer another key question:Does the planet's interior still contain large quantities of water like Earth'sdoes?

MakingPlanets Habitable

Plate tectonics and volcanism don'tjust affect how a planet takes shape; they are intimately tied to a planet's habitability.Plate tectonics strongly affects Earth's long-term climate by influencing theprocesses that keep the atmosphere in balance: volcanism, which releasevolatiles into the atmosphere, and subduction, which recycles volatiles back intothe interior. Also, the formation and erosion of Earth's continents have amajor influence on the composition of the oceans and atmosphere. Together,these processes provide the nutrients and a habitable climate for life tothrive.

But what is the delicate geodynamicbalance that ultimately makes a planet habitable? Considering the discovery ofthousands of exoplanets orbiting stars other than our Sun, the answer couldinform our understanding of their nature.

"To unwrap the mysteriesof Venus we have to look under the hood at Venus' interior; it is the enginefor global geologic and atmospheric evolution," said Smrekar. "AreVenus and Earth fundamentally unique worlds? Or are the differences betweenthese 'twins' only cosmetic? Answering this question is key to understandingwhat makes other rocky planets habitable and, ultimately, emerge with life."

Read more about DiscoveryMission proposals selected to develop concept studies here.

News Media Contact

Grey Hautaluoma / Alana JohnsonHeadquarters, Washington202-358-0668 / 202-358-1501grey.hautaluoma-1@nasa.gov / alana.r.johnson@nasa.gov

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VERITAS: Exploring the Deep Truths of Venus - Jet Propulsion Laboratory