Will NASA Choose A Venus Mission After Phosphine Discovery?

Today’s breaking news is the discovery of phosphine gas in the clouds of Venus. The evidence was detected using ground-based telescopes. The question now is whether spacecraft will be sent to further investigate.  NASA’s last dedicated Venus mission was launched decades ago, but two are competing for a chance in the ongoing round of Discovery missions.

The Royal Astronomical Society announced the phosphine gas findings by an international team of astronomers led by Prof. Jane Greaves of Cardiff University during a press conference today. The scientific paper is published in Nature Astronomy.

Headlines proclaimed the possible detection of life because biological activity is one source of phosphine, although the scientists insisted that is only one possibility.  MIT Prof. Sara Seager drove home that point during the press conference.

The United States, Soviet Union, European Space Agency, and Japan have sent dedicated probes to study Venus since the 1960s and additional probes enroute to other destinations have flown past the planet. Enshrouded by clouds composed of sulfuric acid and a surface with pressure 90 times that of Earth and temperatures over 900 degrees Fahrenheit, Venus is difficult to study and definitely inhospitable to humans.

Still, as Earth’s “sister planet,” about the same size as Earth and just next door in solar system terms, it is of great scientific interest.

NASA’s most recent dedicated Venus probe, the Magellan orbiter, was launched in 1989 and operated until 1994 making a detailed map of the surface using a synthetic aperture radar.

Attempts to win approval for a new NASA mission have been unsuccessful so far. NASA periodically invites scientists to compete for missions in its Discovery series of planetary probes. They are smaller than the mid-sized New Frontiers-class missions or flagship missions, the largest and most expensive. Two Venus missions were proposed in the 2015 Discovery round, but neither was selected.

Another Discovery round is currently in competition and those Venus missions are again in the mix: DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus) and VERITAS (Venus Emissivity, Radio Science, inSAR Topography and Spectroscopy).

DAVINCI+ consists of an orbiter and a probe that would descend through the atmosphere. VERITAS is an orbiter with a synthetic aperture radar.

Does the phosphine discovery heighten the chances that at least one of them will be chosen?  NASA Administrator Jim Bridenstine expressed enthusiasm in a tweet today.

Life on Venus? The discovery of phosphine, a byproduct of anaerobic biology, is the most significant development yet in building the case for life off Earth. About 10 years ago NASA discovered microbial life at 120,000ft in Earth’s upper atmosphere. It’s time to prioritize Venus. https://t.co/hm8TOEQ9es

— Jim Bridenstine (@JimBridenstine) September 14, 2020

The head of NASA’s Science Mission Directorate (SMD), Thomas Zurbuchen, was somewhat less ebullient, however.

As with an increasing number of planetary bodies, Venus is proving to be an exciting place of discovery, though it had not been a significant part of the search for life because of its extreme temperatures, atmospheric composition and other factors: https://t.co/DBtNSeeY6Y pic.twitter.com/hTeRDcn9TW

— Thomas Zurbuchen (@Dr_ThomasZ) September 14, 2020

Two of the next four candidate missions for @NASASolarSystem’s Discovery Program are focused on Venus, as is Europe’s EnVision mission, in which NASA is a partner. Venus also is a planetary destination we can reach with smaller missions. https://t.co/mmu1Ik07Bw pic.twitter.com/ZN9pwUkQyb

— Thomas Zurbuchen (@Dr_ThomasZ) September 14, 2020

The decision is expected next year. Lori Glaze was the Principal Investigator (PI) for DAVINCI in the 2015 competition. She is now Director of SMD’s Planetary Science Division and Jim Garvin of NASA’s Goddard Space Flight Center is DAVINCI+’s PI. Suzanne Smrekar of the Jet Propulsion Laboratory is the PI for VERITAS.

Government-funded missions may not be the only option. Peter Beck, founder and CEO of Rocket Lab, is passionate about sending a privately funded mission to study Venus’ clouds and that was before today’s announcement.

Astrobiologist David Grinspoon, author of Venus Revealed and a member of the DAVINCI+ team, is a long time advocate for more spacecraft missions to Venus and the idea that the planet might once have been habitable and its clouds still might harbor life. In a March 2020 interview in The Space Review he argued that “I’m not saying I think there is life on Venus, and we have to go find it. But there’s a whole industry in looking for life on Mars in aquifers that may or may not be there. And I would put Venus in the same category of plausibility.”