NASA selects 2 Venus missions to explore Earth’s ‘hellish’ neighbor

For decades, scientists who study Earth’s neighbor Venus have watched with dismay as NASA sends mission after mission to Mars.

The last time the United States visited Venus was in 1989, when it sent the spacecraft Magellan to map the topography of the “hellish” planet. Although Venus is roughly the size of Earth, the planet is fundamentally different, encased in a dense, toxic atmosphere of carbon dioxide. The air pressure on Venus’ surface is equivalent to the pressure experienced a mile beneath Earth’s oceans.

Now, a Wesleyan professor is playing a key role in two newly-announced NASA missions to Venus.

“The question has always been, if you have two Earth-sized planets right next to each other, and one of them is habitable and teeming with life, and the other is not, what happened?” said Dr. Martha S. Gilmore, a professor of earth and environmental sciences at Wesleyan University in Middletown.

At long last, the moment to answer that question has come. Last week, NASA selected two Venus missions, both of which Gilmore helped develop, for its Discovery Program. Each project will receive about $500 million from NASA for development. The missions are expected to launch by 2028 to 2030.

One mission, VERITAS, will send an orbiter to Venus to create high-resolution imaging of the planet’s surface and gather data on the composition of its rocky topography. The other mission, DAVINCI+, will drop an atmospheric probe through Venus’ harsh atmosphere to measure its chemical composition.

“These two sister missions both aim to understand how Venus became an inferno-like world capable of melting lead at the surface,” NASA administrator Bill Nelson said in a speech last week. “They will offer the entire science community the chance to investigate a planet we haven’t been to in more than 30 years.”

NASA’s selection was a thrilling victory for Gilmore and other scientists in the small, insular research community that studies Venus. For years, researchers have submitted proposals to return to the planet, only to see them passed over in favor of other projects. In 2017, both Venus missions were in contention for NASA funding but lost out to two asteroid missions.

It’s different this time around.

“The relief we feel, it’s like, ‘Oh my god, finally!’” Gilmore said.

‘Other Earths’

Gilmore has been enamored of Venus since she was a doctoral student at Brown University, back when the Magellan mission was deployed. Although she has also studied Mars extensively over the course of her career, she has always been drawn to Venus, partly because the planet may hold the key to understanding what she calls “the basic building blocks of planets.”

“As we look out there, we want to find other Earths. We want to look at Earth-sized planets,” Gilmore said. “And so what better way to do that than to study an Earth-sized planet that we have access to, which is Venus?”

The Soviet space program began exploring Venus in the early 1960s and eventually landed spacecraft on the planet’s surface that took images of its rugged, rocky terrain — before getting crushed under the intense heat and pressure. Magellan spent four years in Venus’ orbit and mapped the planet’s surface, returning images that, at the resolution of a football field, showed that it was covered in ancient lava flows, indicating a history of volcanic activity.

Over the last decade, Gilmore said, scientific research has shown evidence for active volcanism on Venus, and new models have indicated that the planet’s climate may have been habitable for billions of years. The two new missions will provide the most extensive opportunity in years to explore the many unanswered questions about Venus — and our solar system.

For instance: Why do some planets become habitable while others don’t? Where does water come from? Do planets have an initial supply of water, or does it arrive from comets or meteorites?

“The imaging that DAVINCI+ will do and then mapping that VERITAS will do will let us look at landforms. That’s how we identified water on Mars: We can see sedimentary rocks; we can look for river channels and morphology,” Gilmore said.

In addition to obtaining high-resolution images of Venus’ surface, VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), the orbiter, will conduct a spectroscopy to determine the composition of the planet’s rocks, enabling scientists to study how the rocks were formed. Gilmore specializes in studying the oldest rocks on Venus, and her research suggests that those rocks are “compositionally different than the younger lava flows and different in a way that suggests they were formed in the presence of water.”

As it falls toward Venus’s surface, DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus) will have just 62 minutes to collect data and measure the atmosphere’s chemical composition. The probe is not designed to withstand the impact of landing.

On the DAVINCI+ mission, Gilmore has worked to fit the probe with a camera that will return high-resolution images of “tesserae,” unique geological features on Venus which may be similar to the Earth’s continents.

“As we go down over these old terrains, we can get images of them at the centimeter scale, to understand what those rocks are,” she said. “Are they sediments? Are there channels down there? We don’t know.”

Preparing for the launch

The two Venus missions are still seven to nine years away from being launched. In the coming years, Gilmore and other scientists will work with engineers to refine the mission designs. Gilmore is also conducting experiments on rocks that will eventually help her interpret the data the missions generate.

The real work begins once the missions are complete and a fresh trove of data is available for analysis — a task that Gilmore’s undergraduate and graduate students will be able to assist on.

“That’ll probably take me through the rest of my career,” she said.

For now, Gilmore said she’s proud of the work the Venus community has done to get to this point. And she’s eagerly anticipating the work to come.

“I’m still shocked,” she said. “But I’m thrilled.”