The VASI (Venus Atmospheric Structure Investigation) instrument aboard NASA’s Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging, or DAVINCI, mission to Venus, along with the other instruments on this mission, aims to uncover the mysterious atmosphere of Exploring Venus through a more detailed view than ever before.
VASI will be installed on the descent sphere of the DAVINCI mission to parachute through the atmosphere of Venus. The descent sphere carries a sophisticated array of five instruments, including VASI, designed collectively to study the characteristics of the atmosphere and measure how it changes as it descends.
VASI measurements will provide new information about Venus’ temperature, pressure and wind, and will provide the primary altitude reference for the descending sphere’s atmospheric composition instruments as it plunges into Venus’s scorching, crushing atmosphere.
“There are actually some big puzzles about the deep atmosphere of Venus,” said Ralph Lorenz, a scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, who is in charge of the scientific lead for the VASI instrument. “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 get closer to the surface.”
One of the many mysteries of Venus’ thick atmosphere is its structure, how volcanoes interacted with the atmosphere, and what that interaction can tell us about Earth’s future.
“The long-term habitability of our planet, as we understand it, relies on the coupling of 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 geological time, depends on volcanoes.” An important question is whether volcanoes are still active on Venus. Detailed, altitude-resolved measurements of atmospheric temperatures, wind and composition will help answer this question.
But clouds of sulfuric acid, atmospheric surface pressure about 90 times that of Earth, and surface temperatures around 900 F (about 460 C) make Venus incredibly challenging to explore, and making instruments that can take sensitive measurements is a daunting task. do while exposed to the harsh environment of Venus. Therefore, most sensors from DAVINCI and other subsystems are enclosed in a descent sphere built like a submarine, with sturdy construction to withstand the intense atmospheric pressure and effective insulation to protect these systems from the intense heat near the surface of the sea. Venus. However, VASI’s sensors must be directly exposed to these harsh conditions in order to do their job.
“Venus is difficult. The conditions, especially low in the atmosphere, make it very challenging to develop the instrumentation and the systems to support the instrumentation,” Lorenz said. “All that has to either be protected from the environment or somehow built to tolerate it.”
As the sphere descends to the surface of Venus, VASI will record the temperature variations of the atmosphere with a temperature sensor wrapped in a thin metal tube, like a drinking straw. The atmosphere heats the tube, which the sensor measures and records while protecting it from the corrosive environment.
At the same time, VASI will measure atmospheric pressure using a small silicon membrane enclosed in the instrument. On one side of the membrane is a vacuum and on the other side is the atmosphere of Venus, which will push on the membrane and stretch it. This strain is measured and used to calculate the strength of the pressure.
VASI will also measure wind speed and direction using a combination of accelerometers and gyroscopes installed in the descender, plus Doppler tracking. Accelerometers measure changes in speed and direction, while gyroscopes measure changes in orientation. Doppler tracking also measures changes in speed and direction by measuring the frequency shift of a radio signal from a transmitter in the descending sphere, similar to how an ambulance siren changes tone as it races past.
The various sensors and housings for VASI are being assembled by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, under the scientific direction of APL’s Lorenz. The Doppler measurements are implemented in DAVINCI’s radio system built at APL.
NASA Goddard is the primary research facility for DAVINCI and will perform project management for the mission, providing scientific instruments and project systems engineering to develop the descent sphere. Goddard also leads the project science support team with an outside science team from across the US and including international participation.
NASA’s DAVINCI mission to take the plunge through Venus’ vast atmosphere
Quote: A new instrument will measure temperature, pressure and wind on Venus (2022, October 20) retrieved October 20, 2022 from https://phys.org/news/2022-10-instrument-temperature-pressure-venus.html
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