We’re going back to Venus!
Last week, NASA announced that it had selected two new missions to Venus to join its Discovery program, which funds small spacecraft proposals to explore the solar system. Past Discovery missions included the famous Kepler planet-hunting telescope, and the soon-to-launch Lucy and Psyche spacecrafts which will explore various asteroids. Each of the new selected missions — known as DAVINCI+ and VERITAS — will plan to launch by 2030.
It’s been quite a while since NASA has been to Venus — the last NASA orbiters, known as the Magellan spacecraft, orbited the planet in the 1990s. Since then, the European Space Agency sent their Venus Express orbiter from 2005 to 2014, and the only spacecraft currently in orbit around Venus is Japan’s Akatsuki, which arrived in 2015. In the entire history of Venus exploration, we’ve only seen the surface for a few hours with the Soviet Venera landers in the 1970s — the landers took photos until they were crushed and melted by Venus’ suffocatingly thick atmosphere.
Venus returned to front-page news after the detection of phosphine, a possible sign of life, last fall. This momentous discovery was the first plausible detection of a biosignature (a chemical element that can only be produced by life). However, experts are still debating the conclusions: some astronomers disagree with the methods of analysis, others reject the idea that phosphine can only be produced by life.
Even if the phosphine detection wasn’t a surefire sign of life, it reignited interest in our sister planet, which is often thought of as too hot and too inhospitable to host life. We do know the Venusian surface isn’t likely to be habitable — Venus’ atmosphere consists of carbon dioxide and sulfuric acid, which leads to acid rain and crushing pressures 90 times more dense than Earth’s on the surface. But what if life evolved on the planet before these toxic conditions took hold of the surface? If that life moved up into Venus' clouds, temperatures and pressures could be comfortable enough for it to persist. Some scientists propose that microbial life may exist aloft in the clouds, and could produce a phosphine signature.
It’s worth mentioning that Venus isn’t the only exciting place for weird life in our solar system. For example, outer solar system moons, like Jupiter's Europa and Saturn's Enceladus, have water oceans that might hold life. Two other proposed missions that would explore some of these interesting, weird worlds — the Io Volcano Explorer, which would visit Jupiter’s volcanic moon Io, and the Trident expedition to Neptune’s icy moon Triton — lost the NASA Discovery program bid in favor of DAVINCI+ and VERITAS.
The first of the two new spacecraft, DAVINCI+, or the Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging, will dive into the atmosphere to make measurements and take a peek at Venus’s elusive surface. Using a variety of instruments, such as a mass spectrometer and an imaging camera, DAVINCI+ will make measurements inside the atmosphere that can help scientists figure out how the history of Venus differs from that of Earth and Mars — did Venus ever have an ocean, and if so, where did it go? The probe will also take images of rock formations known as “tesserae” on the surface. Tesserae are analogous to our Earth’s continents, so scientists expect studying them will reveal important insights into Venus’s plate tectonics and how rocky planets form.
The second chosen proposal for VERITAS, or Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy, takes a different approach to understanding Venus. VERITAS will orbit the planet and study its geology from afar. Using radar and infrared images the orbiter will create detailed maps of Venus’s surface topography and composition. Knowing how Venus' surface landscape is shaped will improve our understanding of the planet's geology and find any possible hints of past or present water.
Both missions also include “technology demonstrations” — new bits of tech that are more experimental, and NASA engineers want to see how they work before implementing them as crucial parts of future missions. DAVINCI+ will carry an instrument known as CUVIS, a new kind of spectrometer that measures high energy ultraviolet light. The idea is that it will help figure out what mysterious substance in Venus’s atmosphere is absorbing a large chunk of incoming sunlight — some scientists think it's a kind of gas like sulfur dioxide, and some scientists suggest it might even be microbes! VERITAS will have a new version of the Deep Space Atomic Clock, an ultra-precise clock that will allow future spacecraft to navigate more accurately than ever before.
NASA isn't the only agency making plans to check out Venus, either. The European Space Agency announced earlier this week that they too are sending an orbiter to our sister planet, also launching in the early 2030s. Known as EnVision, the orbiter will carry a radar instrument to map the surface, a sounder to see underground, and more. Together with DAVINCI+ and VERITAS, the ESA claims that this "trio of new spacecraft will provide the most comprehensive study of Venus ever."
These missions aren't slated to launch until later this decade, but the journey to Venus will only take a few months once the launch happens. Although we still have a while to wait, a revolution in our knowledge of Venus is on the horizon. It's about time we get to know our next door neighbor better!