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The Fiery Plunge

by Perry Pezzolanella

A new mission to probe the atmosphere of Venus and land on its surface was approved on June 2, 2021. DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging), named after the famous Renaissance visionary artist and scientist, Leonardo da Vinci, is the first NASA mission since 1978 for a probe to descend to the surface. It is a combination flyby/probe mission. The flyby remote-sensing carrier relay imaging spacecraft (CRIS), simply called the carrier because it carries the probe, will image Venus in multiple wavelengths from above, while the descent probe will study the composition of the atmosphere and take photographs during descent to the surface.

The past five missions to Venus have all been orbital missions. Venera 15&16, Magellan, Venus Express, and Akatsuki focused on remote observations. DAVINCI will be the first probe to enter the atmosphere since the Soviet Vega probes in 1985 and will make direct measurements in the lower two-thirds of the atmosphere, including below the cloud deck. Scientists will explore how the atmosphere of Venus formed and changed over time, including what happened to the water that might have once existed on the surface.

There are three main goals of this mission: 1). Atmospheric origin and planetary evolution: What is the origin of the Venus atmosphere and how has it evolved? Was there any early ocean on Venus, and, if so, when, and where did it go? How and why is Venus different from (or similar to) Earth, Mars, and Venus-like worlds discovered around other stars? 2). Atmospheric composition and surface interaction: Are there currently active volcanoes and what is the rate of volcanic activity? How does the atmosphere interact with the surface? What are the chemical and physical processes in the clouds and subcloud atmosphere? 3). Surface properties: Are there any signs of past processes in surface morphology and reflectance? How do tesserae compare with other major highlands and lowlands?

DAVINCI is designed to explore the noble gases, trace gases, and their isotopes, as well as temperature, pressure, winds, and imaging at Venus. The descent probe has five instruments which include the Venus Mass Spectrometer (VMS) which will study the noble and trace gases during its descent and has the ability to discover new gases. The Venus Tunable Laser Spectrometer (VTLS) will provide the first highly sensitive measurements of trace gases and isotope ratios that will address questions about chemical processes. The Venus Atmospheric Structure Investigation (VASI) will measure the pressure, temperature, and winds from an altitude of about 44 miles all the way down to the surface. After the probe drops under the thick cloud layer, the Venus Descent Imager (VenDi) instrument will take hundreds of near-infrared images of Alpha Regio, ancient rugged mountainous highlands twice the size of Texas, where the probe will land. The Venus Oxygen Fugacity Student Collaboration Experiment (VfOx) is a solid-state ceramic oxygen sensor derived from high-temperature industrial sensors. It will measure the oxygen composition of the lower atmosphere of Venus, with emphasis on the oxidation state of surface rocks at the landing site and help determine the surface-atmosphere exchange chemistry. Scientists will be able to make maps of the topography and composition from the images as the resolution aloft of the landscape will rival a lander on the surface. The probe will look for evidence that past crustal water influenced the surface rocks, which is suspected in the tesserae regions.

The carrier spacecraft will have two instruments with one instrument consisting of four cameras called the Venus Imaging System from Orbit for Reconnaissance (VISOR). One camera will be sensitive to ultraviolet light to track cloud motions in the atmosphere. The other three cameras will be sensitive to near-infrared light and will be able to identify surface composition by analyzing heat emission from the surface when the spacecraft is on the night side of Venus. Rock composition can be influenced by water, so these images will give clues to how ancient oceans may have shaped the crust. Ishtar Terra, with mountains nearly seven miles high, will be the target of study as it may be the last evidence of plate tectonics before Venus lost its suspected oceans around a billion years ago. The other instrument is the Compact Ultraviolet to Visible Imaging Spectrometer (CUVIS). This is new technology that will demonstrate combining high-resolution ultraviolet spectroscopy and hyperspectral imaging from the ultraviolet to the visible wavelengths into a compact package using optics and artificial intelligence machine-learning onboard data processing. It will analyze the data in real time and prioritize full-resolution data to transmit back to Earth. It will be able to obtain spectra of the clouds far better than any spacecraft and determine upper cloud composition. It will provide clues to the mysterious ultraviolet absorber in the upper clouds along with cloud features, structure, and chemistry. CUVIS will observe Venus in full Sun during both flybys.

DAVINCI is scheduled to launch in June 2029 with two flybys of Venus before releasing the descent probe in June 2031. The first flyby will occur in January 2030 and the second during November 2030. Dayside ultraviolet observations will be made as well as nightside surface measurements of key highlands such as tesserae and the suspected volcanically active Maat Mons. DAVINCI will then be in perfect alignment to arrive back at Venus in seven months and deploy the probe on June 2, 2031, with landing at Alpha Regio on June 21, 2031. Solar illumination will be favorable for high-sensitivity near-infrared imaging under the clouds as the probe descends to the surface. The targeted entry-descent-imaging site within Alpha Regio is large enough so that a precisely controlled descent is not necessary. The touchdown ellipse is comfortably within the tesserae highlands and will allow for high-resolution descent images to map local infrared emissivity and local topography of this unique region. After atmospheric entry and parachute deployment at an altitude of around 44 miles, the heat shield is released and the instruments on the probe will begin to collect and return high-quality measurements of noble, trace gas, and isotopic abundances; atmospheric temperature, pressure, and winds; and high-resolution broadband and narrowband descent images of Alpha Regio. It will be a hard landing at 25 miles per hour and not designed to operate as a lander, but if it does survive, it will conduct science and relay data from the surface for an additional 15-20 minutes. Since the camera is facing downward, it cannot take panoramic images of its surroundings and will most likely be damaged upon impact.

The Golden Age of Venus Exploration has arrived with DAVINCI pioneering the way for two other newly approved Venus missions, VERITAS and EnVision, toward a decade of Venus exploration in the 2030s with visions of long-lasting landers, rovers, and eventually sample return missions to follow. After falling through sulfuric acid mist, the life of the DAVINCI probe will be brief as it takes an hour-long plunge into the fiery heat below with temperatures approaching 900ºF and crushing atmospheric pressure over 90 times Earth’s, but the amount of data and images gathered during its brief life will be a treasure trove for generations of scientists.