Season 17, Episode 7: DAVINCI and the Mysteries of Venus

Hey StarTalkians! In Season 17, Episode 7, Neil and Chuck sit down with planetary astrobiologist David Grinspoon to talk about the upcoming DAVINCI mission to Venus. As Grinspoon euphemistically explains, the mission aims to “reach” (i.e. “crash on”) the surface of the planet and resolve some key mysteries in the process.

Why We’re Going Back to Venus, with David Grinspoon

If you know anything about Venus, you’ll see the challenge here. The Venusian surface is much hotter than any other planet in the solar system – at 464 °C (867 °F), hot enough to melt lead (Solar System Temperatures - NASA Science). The atmosphere is also suffocated with clouds of sulphuric acid, but it may have been more Earth-like in the past.

So what will DAVINCI be looking for on this hellish planet?

The Mysteries of Venus: What DAVINCI Will Measure

There are three key questions the DAVINCI mission will investigate in 2031 (Revealing the Mysteries of Venus: The DAVINCI Mission):

1. Atmospheric origin and Venusian water: Was Venus habitable in the past? Venus seems to have a much higher deuterium-to-hydrogen ratio than Earth. This could result from the splitting of water vapour, because hydrogen is lighter than deuterium, so more of it would be lost to space. A previous attempt to measure this ratio failed because the instrument got clogged with sulphuric acid. DAVINCI’s instrument will vaporize any such droplets, and the resulting measurement will allow scientists to test the history of water on the planet.

2. Atmospheric composition, impacts and volcanic history: Noble gases, especially argon-40, helium-4, xenon-129 and xenon-136 will help the team pin down the history of volcanic activity and impact events on Venus. For example, high xenon-129 would suggest Venus didn’t have a giant impact like the one on Earth which formed the moon. The gases within 20 km of the surface are relatively unknown, so DAVINCI will investigate this, along with carbon, hydrogen, nitrogen, oxygen, sulphur and phosphorus-containing compounds, elements critical to life on Earth.

3. Imaging the tessera: The coolest part of the mission for non-scientists will be the images from the descent, as the probe approaches a region known as Alpha Regio, a “tessera.” These may be ancient continents, raised up from the surface a bit like a mountain range. It will likely give us the clearest view ever of Venus’ surface.