NASA scientists are preparing to paint the most detailed picture yet of Venus’s atmosphere when the aptly named DAVINCI — or Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging — mission drops a probe onto the planet’s surface.
When the DAVINCI mission’s 0.9-meter (3-foot) wide descent sphere makes its one-way parachute flight VenusSurface in the early 2030s, it will carry the VASI (Venus Atmospheric Structure Investigation) instrument along with five other instruments. VASI collects data on temperature, pressure and wind The Atmosphere of Venus as it makes its hellish descent and enters the planet’s crushing lower atmosphere.
“There are actually some great mysteries about the deep atmosphere of Venus,” said Ralph Lorenz, scientific director of the VASI instrument and planetary scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Maryland, in a expression. “We don’t have all the pieces of this puzzle and DAVINCI will give us those pieces by measuring composition at the same time as pressure and temperature as we approach the surface.”
Venus’ dense atmosphere hides several mysteries, including its structure and the interaction of the planet’s many volcanoes over the eons. One of the scientists’ main goals is to dip a probe through the atmosphere of the second planet Sun is to determine if this world is still volcanically active. The probe could sniff this out by taking measurements of atmospheric temperatures, winds and composition.
Solving these mysteries could give scientists an idea of what continued volcanic activity could mean for our own planet’s atmosphere.
“The long-term habitability of our planet as we understand it is based on the coupling of interior and atmosphere,” said Lorenz. “The long-term abundance of carbon dioxide in our atmosphere that we really rely on to keep the Earth’s surface warm enough to be habitable over geological time scales is due to volcanoes.”
A one-way trip to Venus
One of the greatest challenges associated with exploring Venus has been the extreme conditions of the planet, which has a surface pressure up to 90 times that of Venus Earth and surface temperatures around 900 degrees Fahrenheit (460 degrees Celsius).
Also, before an orbiting probe can reach the planet’s surface, it must first fly through clouds of sulfuric acid in Venus’ upper atmosphere. (These clouds also make Venus difficult to observe from Earth; reflective and shiny, they obscure our view of the planet’s surface.)
These threats mean DAVINCI’s descent sphere systems and sensors are encased in a robust, submarine-like structure. But while the sphere is built to withstand intense atmospheric pressure and insulated to shield the sensors from the intense heat near Venus’ surface, VASI’s sensors need some exposure to the harsh conditions to do their job.
“Venus is hard. The conditions, especially deep in the atmosphere, make it very difficult to construct the instrumentation and the systems to support the instrumentation,” Lorenz said. “All of that has to either be protected from the environment or somehow built to tolerate it.”
As the sphere falls through Venus’ atmosphere, VASI measures the temperature with a sensor in a thin, straw-like metal tube. As the atmosphere heats the pipe, the sensor measures and records the expansion, and therefore temperature, without being directly exposed to the corrosive environment.
VASI captures atmospheric pressure readings using a silicone membrane enclosed within. One side of the membrane is exposed to a vacuum while the other side faces Venus’ atmosphere. The atmosphere pushes and stretches the membrane, and the amount of this stretching indicates the magnitude of the atmospheric pressure.
The instrument measures Venusian winds using a combination of accelerometers, which test changes in speed and direction, and gyroscopes, which measure orientation. The mission will also track changes in wind speed and direction by monitoring changes in the frequency and wavelength of radio waves.
DAVINCI, named after Italian Renaissance polymath Leonardo da Vinci, is currently scheduled to launch in 2029. If the schedule is followed, the Descent Orb will plummet through Venus’ dense atmosphere in 2031.
The drop takes about an hour. The probe isn’t expected to survive the fall, but if it does, NASA scientists are prepared to use the doomed device to bring about 17 minutes of extra science to the surface.