As planetary scientists resumed meeting in person, Venus experts had something special to celebrate.
For decades, the Venus community has been crying out for missions: Only one dedicated spacecraft is currently studying our next-door neighbor, and NASA's last robotic Venus visitor ended its mission in 1994. Within just a couple weeks in 2021, however, Venus scientists suddenly had a veritable banquet to look forward to, with NASA and its European counterpart committing to three new missions due to launch in the early 2030s.
For planetary scientists who focus on Venus, this year's Lunar and Planetary Science Conference (LPSC) held in Texas and virtually was an opportunity to celebrate the triumph.
"I would like to just take a moment to acknowledge how fantastic it is that we've actually moved now from talking about what proposed Venus missions could do to actually talking about what our missions will do at Venus," Jörn Helbert, a planetary scientist at the German space agency DLR, said during a talk on Tuesday (March 8). "This is just an incredible moment."
Over a few short weeks of June 2021, NASA committed to two new Venus missions, VERITAS and DAVINCI, while the European Space Agency greenlit one called EnVision. All three are expected to conduct the bulk of their observations in the early 2030s and are designed to revolutionize scientific study of the planet.
Venus scientists have taken to celebrating "the decade of Venus," and the moment has been a long time coming. "The Venus community, we are tight," said Martha Gilmore, a planetary geologist at Wesleyan University in Connecticut who focuses on Venus and who gave a plenary talk to the conference on Monday (March 7). "We've been battling this whole time and proposing."
Even with a decades-long gap in NASA missions, that work hasn't been in vain: Neither VERITAS nor DAVINCI was a first-time proposal, allowing scientists to sharpen their designs until selection. Still, Venus boosters have struggled to keep convincing scientists to dedicate their careers to a planet with such a dearth of missions.
Gilmore referenced her first LPSC, in 1992 during NASA's last era of Venus spacecraft, noting that the program included three full days of Venus talks. The planet isn't quite back to its former glory, but this year, presentations about the planet next door filled out the conference schedule on Tuesday, with talks spanning topics including strange geological features, Venus' long-lost oceans and cloud activity.
The day began with VERITAS principal investigator Sue Smrekar, a planetary scientist at NASA's Jet Propulsion Laboratory in Southern California, who offered an introduction to the mission she first proposed to the agency in 2015.
VERITAS, targeting launch in 2027, is tailored to peer through the planet's thick clouds and give scientists their first glimpse of the Venusian surface since the end of NASA's Magellan mission in 1994. The spacecraft's instruments will offer data about rock composition, geologic activity and the planet's interior.
"VERITAS will produce these incredible foundational datasets that will just tell us so much about Venus and pave the way for the 'decade of Venus' and all the exciting investigations that are going to be discussed today and hopefully many, many future missions," Smrekar said.
One of the instruments aboard VERITAS, the Venus Emissivity Mapper, will see a near-twin fly on ESA's mission EnVision, targeting launch in the early 2030s. With their staggered arrivals, the pair of instruments will complement each other, Helbert said during his presentation, particularly because Venus is the only inner planet where rock types have not been mapped across the full surface. The instruments will also be able to identify whether Venus' surface hosts any active lava flows: such features would glow compared to cooler rock nearby and give clouds above an eerie shine.
Other speakers teased their own anticipated science returns from the trio of Venus missions. While the strength of VERITAS and EnVision's science focuses on the planet's surface, DAVINCI's observations will emphasize Venus' thick, carbon-rich atmosphere. Unlike the other two missions, DAVINCI, which is targeting launch in 2030, includes two components: a main spacecraft and an atmospheric probe that will spend about an hour coasting down to the surface.
DAVINCI's probe will land in a particularly complex area called Alpha Regio, the target of research presented by Margaret Deahn, a graduate student working with Gilmore at Wesleyan University. "It's pretty intimidating," Deahn said of the landscape, where she is working to pick apart a web of ridges, troughs and other features in advance of the probe's arrival.
Gilmore attributed the Venus community's sudden wealth of missions to both the scientists' work and two lucky breaks. One was the September 2020 announcement of phosphine detected in Venus' atmosphere. On Earth, the chemical is associated with life, and the detection spurred a rush of renewed interest in the planet's habitability throughout time.
The other stroke of luck was the cross-disciplinary partnerships formed with exoplanet scientists in recent years as the number of known alien worlds has skyrocketed. The first data points scientists typically gather about an exoplanet are its size and its orbital distance from a star. By those criteria alone, Earth and Venus look essentially the same, and many exoplanets look more or less like Venus.
"Exoplanets: who knew, they're everywhere and a lot of them are Venus-size," Gilmore said. "The exoplanet folks and the Venus folks have become like BFFs because we're trying to understand how an Earth-size planet happens."
But if getting a spacecraft mission to Venus has been difficult, getting one to an exoplanet will be impossible. "This is a rather haunting thing to think about," Stephen Kane, an astronomer at the University of California, Riverside said during his presentation. Instead, exoplanet scientists interested in rocky, potentially habitable worlds can only work from spacecraft studying the few terrestrial planets in our own solar system. And for questions of atmosphere, Venus is an obvious reference point, since its atmosphere is by far the most massive.
So while Venus scientists will still face a four-decade drought in NASA data about the planet next door, brighter days are finally ahead of them. Gilmore celebrated, she told the audience, by changing her license plate to read "TO VENUS."
"There's so much that we can do with this opportunity to go to Venus," Gilmore said. "We are all invested, I think, in learning everything we can with this opportunity."