(ORDO NEWS) — The surface of Venus is utterly inhospitable to life: barren, dry, crushed by an atmosphere about 90 times Earth‘s pressure, and roasted at twice the temperature of an oven.
But has it always been like this? Could Venus have once been Earth’s twin – a habitable world with oceans of liquid water? This is one of the many mysteries associated with our shrouded kindred world.
It has been 27 years since NASA‘s Magellan mission last orbited Venus. This was NASA’s most recent mission to sister planet Earth, and while we’ve gained considerable knowledge of Venus since then, there are still many mysteries about the planet that remain unsolved.
NASA’s DAVINCI (Venusian Deep Atmospheric Noble Gas, Chemistry and Imagery Exploration) mission hopes to change that.
Here are ten mysteries of Venus that NASA scientists are still wrestling with:
1- Was there ever life on Venus?
What is the question most often asked when thinking about other planets: is there life? Was there ever life? If so, what is this life? Tiny microbes that resemble simple life on Earth? Or something we’ve never seen before?
Venus is no exception.
“The community has been speculating about possible life on Venus, but until we know whether Venus was ever actually habitable in the past, it’s hard to say anything more than these speculations,” says Dr Jada N. Arnie, DAVINCI Deputy Principal Investigator at NASA’s Goddard Space Flight Center.
“DAVINCI aims to help us understand whether Venus was ever habitable, which will provide a more concrete basis from which we can study it as a possible past habitat for life… It is interesting to think that there is a possibility that in our solar system, two inhabited worlds have been adjacent to each other, perhaps even for billions of years, but we do not yet know if this was the case.
To determine whether life was ever possible on Venus, we first need to understand the environment on Venus in the past. This includes studying the atmosphere, geology and history of the planet.
“We always want to ask a life question, but until we understand the context in which we ask it, we won’t know what we’re looking for and may be even more confused or tortured,” explains Dr. James B. Garvin, DAVINCI Principal Investigator at NASA.
2- How did Venus and Earth become so different?
Venus and Earth are similar in size and density, so hypothetically these planets could be very similar. And yet they are strikingly different from each other.
The air pressure on the surface of Venus is 90 times that of Earth, Venus rotates on its axis in the opposite direction compared to other planets in the solar system, and the surface temperature of Venus is over 900 degrees Fahrenheit (over 482 degrees Celsius), making it the hottest planet in our solar system, hot enough to melt lead.
This extreme heat on the surface of Venus is due to a carbon dioxide atmosphere with thick clouds of sulfuric acid that may have resulted from a runaway greenhouse phase early in Venus’s history that forever changed our sister world.
So what happened? Was Venus always so inhospitable? “Why are we so good and they are so bad?” Garvin asks. “This is a central question because in the long run it will affect the evolution of our own planet. Maybe Venus is a storyboard of fate that will help us fill in our planet’s longer history.”
The evolution of Venus over time can help us understand the processes that drive global changes in the planet’s environment, including the evolution of the planet’s habitability, with implications for where we might find habitable planets outside the solar system.
“Venus provides an important illustration of how planetary environments can evolve over time, and the understanding that evolution is critical to our thinking in search of life beyond Earth,” explains Dr. Stephanie A. Getty, DAVINCI’s Associate Principal Investigator NASA.
3- How was Venus formed?
Even this seemingly basic question about the origin of Venus is still a mystery. “It’s amazing to me that we don’t know if Venus formed from the same materials in the early solar system as Earth and Mars,” Getty says.
“We still don’t know if Venus has been bombarded by comets and water-rich asteroids, as was the case on Earth.”
These comets and asteroids that bombarded our home planet are considered an important source of water for the Earth. Understanding the delivery of water to Venus is important in assessing its potential to host oceans in the past.
4- What is the composition of the atmosphere on Venus?
The composition of Venus’s atmosphere is an important part of the context we are looking for as we seek to better assess the potential habitability of Venus over time.
“We don’t really know the important chemicals in Venus’s atmosphere,” says Garvin. “We don’t understand the chemical cycles that give clues to how it evolved and the role of those chemical cycles in Venus’s history – these unknowns are fingerprints that have been missing for far too long.”
The DAVINCI probe will measure chemical composition, pressure, temperature and dynamics at least every 200 meters as it descends through the atmosphere of Venus. One of the biggest mysteries of Venus’s atmosphere lies in the lowest, or “deep” atmosphere.
As a rule, the atmospheric gases of the planets behave in the same way as those that we study in high school chemistry – their behavior can be assessed as “ideal gases” and well understood.
But in Venus’s lower atmosphere (closest to the planet’s surface), carbon dioxide is heated and pressurized to the point where it acts more like a hot liquid than a gas about twelve times less dense than liquid water.
“This strange behavior is called ‘supercritical’, and on Venus the atmosphere that sloshes around surface landscapes and rocks is supercritical carbon dioxide, which is poorly understood,” says Garvin.
“We have to go out there and measure what’s going on to figure out how it works on a planetary scale. This means that a whole new frontier has opened up on Venus. It’s a new state of the environment that we’re not used to.”
5- How were the rocks of Venus formed?
The last spacecraft to successfully descend through the atmosphere and land on Venus was the Soviet VeGa-2 mission in 1985, which lasted 52 minutes on the planet’s inhospitably hot surface on the “night side”.
At the landing site, it was surrounded by volcanic basalt plains, but some high-altitude areas on Venus are thought to be different. Thus, the surface of Venus remains rather mysterious, especially in regions outside the volcanic plains.
The DAVINCI spacecraft will be equipped with a set of four cameras, called VISOR (Venus Imaging System for Surveillance Reconnaissance), that will be able to determine the composition of rocks on the planet’s surface.
“Much of the surface of Venus is made up of basalt, which is formed as a result of volcanism,” says Arnie. “But there are some intriguing mountainous highlands called ‘tessers’ (areas of highly deformed terrain) that suggest hints of a different composition.
They may be made from rocks that form from water-rock interactions and continental-building processes (which could imply Earth-like plate tectonics), and if so, that’s really interesting because it suggests more hospitable conditions in Venus’ past.”
The DAVINCI probe will land on one of these “tesserae” called Alpha Regio and take measurements with its Venus Descent Imager (VenDI). “This will help us better understand what this ‘tessera’ is made of,” explains Arnie.
6- How much water was on Venus?
Liquid water is essential for life. We cannot estimate the past habitability of Venus without knowing how much water Venus might have had, and when and how it lost that water. Scientists can use the bulk chemistry of rocks found on Venus to unravel the mystery of the planet’s water.
“If we find ‘granites’ in the mountains of Venus, we can conclude that they must have contained a lot of water in Venus’s crust to allow them to form the way they do on Earth,” explains Garvin.
Scientists can also use atmospheric measurements to understand the history of water on Venus. The mass spectrometer of the DAVINCI probe on Venus and the laser spectrometer will measure the composition of the atmosphere throughout the descent to the surface of the planet.
Measured atmospheric signatures could provide clues to the history of past water, which could help scientists determine if the planet previously had an ocean. “We suspect, but don’t know, whether oceans existed on Venus, and if so, when in Venus’s history the water evaporated,” Getty says.
7- What is the nature of surface activity on Venus?
Scientists are still discovering whether Venus ever had terrestrial plate tectonics and how similar or different these mountain-building processes are to Earth. The Earth’s crust contains a network of relatively thin plates that move across the planet’s surface in constant horizontal motion.
If such plate tectonics exists on Venus now or in the past, the planet’s crust must experience crustal plate movement over geologic time, mid-ocean ridge volcanism (volcanic activity present at oceanic boundaries between two plates), and subduction (movement of a single plate subducting under another plate).
The history of Venus tectonics is still an active area of research with many open questions. Some scientists believe
At some point, Venus may have had its own form of plate tectonics – perhaps different from the plate tectonics here on Earth.
Water and rock measurements from the DAVINCI mission, combined with global mapping information for Venus from NASA’s VERITAS mission, another recently selected Venus mission operated by NASA’s Jet Propulsion Laboratory in Southern California, can be used to decipher that , how these tectonic structures could act on Venus and why the planet could not support them in the same way as the Earth.
Venus is an ideal example for studying how plate tectonics or some other type of crustal movement persists or disappears on large rocky planets with atmospheres and changing volumes of the earth’s crust and surface water.
Another key mystery of the surface of Venus is volcanism. All planets must get rid of their internal heat. For the Earth, volcanism is used for this – as an accompanying process. Scientists are still speculating about whether the surface of Venus is currently volcanic and to what extent eruptions are occurring today.
Together, the DAVINCI and VERITAS missions hope to address these issues. DAVINCI can measure gases in the atmosphere of Venus, which can signal whether Venus volcanoes have erupted or are erupting today, while the VERITAS orbiter will be able to see the deformation of the surface crust, the chemical signature of recent volcanism, and the heat flows of large erupting lavas.
8- What do mountains look like on Venus?
Previous Venus landers (Venera and VeGa) have photographed the plains of Venus after landing on basalt patches, but DAVINCI cameras will take the first ever high-resolution aerial photographs of the mountainous surface of the tessera when the probe descends over the rugged high Alfa Regio region.
“The place where we land on Venus is in the mountains,” explains Garvin. “No one has ever gone to the mountains before.” Such rugged mountain scenery may hold clues to how erosion on Venus works today. Likewise, they could indicate whether sedimentary rocks played an important role in the formation of the highlands of Venus, as they usually do on Earth.
9- Are there planets like Venus outside our solar system (exoplanets)?
Scientists are excited about the idea of taking what we learn from Venus and applying it to exoplanets – planets outside our solar system.
Venus-like exoplanets are expected to be a common type of planet seen by the James Webb Space Telescope, and more accurate measurements of Venus could help us understand these distant worlds.
“We will be able to correlate what we find on Venus with what we have found from observations of Venus-like exoplanets observed by the James Webb Space Telescope in the 2020s,” says Arnie.
“For example, data from Venus could improve computer models of Venus-like exoplanets that we will use to interpret our future observations of James Webb. Also, if Venus was habitable in the past, that means some of these ”
10- New mysteries we haven’t even thought about yet
“One of the most exciting aspects of planetary exploration is discovering new mysteries that we currently cannot foresee,” says Arnie. “That’s what I’m looking forward to the most.”
This is the essence of curiosity-driven exploration, and DAVINCI will offer many opportunities to discover and even solve new mysteries.
What can Venus hide? We must go there to find out! “Venus, here we come” is the catch phrase of the DAVINCI team.
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