A NASA instrument bound to Venus prepares to brave the harsh atmosphere
NASA scientists are preparing to paint the most detailed picture of Venus’ atmosphere yet when the aptly named DAVINCI — or Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging — mission drops a probe on the planet’s surface.
When the 3-foot-wide (0.9-meter) DAVINCI mission descent sphere embarks on a one-way parachute journey to Venus‘ on the surface in the early 2030s, it will carry the VASI (Venus Atmospheric Structure Investigation) instrument along with five other instruments. VASI will collect data on temperature, pressure and winds Venus’s atmosphere as it descends inferno into the planet’s devastating lower atmosphere.
“There are some big puzzles about the deep atmosphere of Venus,” said Ralph Lorenz, VASI instrument scientist and planetary scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Maryland. statement. “We don’t have all the pieces of that puzzle and DAVINCI will give us those pieces by measuring the composition at the same time as the pressure and temperature as we approach the surface.”
Venus’ thick atmosphere hides several mysteries, including how it is structured, as well as how the planet’s many volcanoes have interacted with it over the eons. One of the key goals of scientists in plunging a probe through the atmosphere of another planet the sun is to determine whether that world is still volcanically active. The probe could sniff it out by measuring atmospheric temperatures, winds and composition.
Solving these puzzles could give scientists an idea of what continued volcanic activity could mean for our planet’s atmosphere.
“The long-term habitability of our planet, as we understand it, rests on the interface between the interior and the atmosphere,” Lorenz said. “The long-term abundance of carbon dioxide in our atmosphere, which we really rely on to keep the Earth’s surface warm enough to be habitable over geologic time, relies on volcanoes.”
A one-way trip to Venus
One of the main challenges related to the exploration of Venus has been the extreme conditions of the planet, which boasts surface pressures up to 90 times greater than Earth and surface temperatures around 900 degrees Fahrenheit (460 degrees Celsius).
In addition, before any probe can reach the planet’s surface from orbit, it must first pass through the sulfuric acid clouds 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 that DAVINCI’s descent sphere systems and sensors will be enclosed within a durable submarine-like structure. But while the sphere is built to withstand intense atmospheric pressures and is insulated to protect the sensors from the intense heat near the surface of Venus, VASI’s sensors must be exposed to some harsh conditions to do their job.
“Venus is hard. The conditions, especially low in the atmosphere, make it very challenging to design the instruments and systems that support the instrumentation,” Lorenz said. “It all has to be either protected from the environment or somehow built to tolerate it.”
As the sphere falls through Venus’ atmosphere, VASI will measure the temperature with a sensor inside a thin metal straw-like tube. As the atmosphere heats the pipe, the sensor measures and records the expansion and thus the temperature without direct exposure to the corrosive environment.
VASI will collect atmospheric pressure readings using a silicon membrane inserted into it. One side of the membrane is exposed to the vacuum while the other side faces the Venusian atmosphere. The atmosphere pushes the membrane, stretching it, and the degree of this stretching reveals the strength of the atmospheric pressure.
The instrument will measure Venus’ winds using a combination of accelerometers that test changes in speed and direction and gyroscopes that measure orientation. The mission will also track changes in wind speed and direction by tracking changes in the frequency and wavelength of radio waves.
Named after the Italian Renaissance polymath Leonardo da Vinci, DAVINCI is currently set for launch in 2029. If it stays on schedule, the descent sphere will pass through the dense atmosphere of Venus in 2031.
The descent will take about an hour. The probe is not expected to survive the crash, but if it does, NASA scientists are poised to gain about 17 minutes of additional science on the surface using the doomed device.
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