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How Long was Venus Potentially Habitable and What Caused it to Become the Volcanic and Acidic Planet it is Today?

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Venusian Habitable Climate Scenarios: Modeling Venus Through Time and Applications to Slowly Rotating Venus Like Exoplanets

by: M.J. Way, Anthony D. Del Genio 

Summarized by: Lisette Melendez

What data were used? Nowadays, Venus is known for its extreme climate. It’s the hottest planet in our Solar System (with a surface temperature of about 840°F!), and the only planet that spins in the opposite direction. In fact, Venus spins so fast that its acidic clouds can travel completely around the planet in 5 days. Despite its extremities, Venus is also known as Earth’s sister planet. Both planets formed very close to one another and their shape and mass are very similar. So how did their surfaces become so distinct from one another? There are many hypotheses posed as to what early Venus looked like, ranging from a stable world with surface liquid water, to a volcanic world with a magma ocean and a carbon dioxide atmosphere. In order to better understand the early history of Venus, scientists used the data that we have about early Earth and simulations generated by various satellites orbiting Venus.

Methods: By modeling early Venus to closely match the conditions of early Earth using NASA’s ROCKE-3D (a tool you can try out yourself!) general circulation models, the scientists were able to examine how changes in factors like surface water and rotation rate affected Venus’s climate.

Results: The team discovered that Venus’s climate may have been stable and temperate with liquid water at its surface for most of the planet’s history, as shown in Figure 2. So, what caused the huge change? The authors argue that it was caused by the synchronized eruption of massive volcanoes, leading to the large igneous provinces (LIPs, or large collection of volcanic rocks) seen on Venus today. These LIPs could have triggered a runaway greenhouse effect on Venus, a situation where a planet absorbs more energy from the sun than it can radiate back into space. This leads to an inability to cool down and to the evaporation of surface water on the planet. On Earth, some LIPs are known to coincide with mass extinctions, so these events are already known to create colossal changes on the surface of a planet.

Figure 1: An image of the harsh surface of Venus, the most volcanic planet in our Solar System. Credit: NASA JPL.

Why is this study important? This study is important because it gives us insight as to whether early Venus ever had life-friendly environments: did the planet ever experience the same evolutionary processes that Earth did? It also helps us understand exoplanets, which are planets outside of our Solar System, which are tens of thousands of years away by rocket travel. Some of these rocky exoplanets orbit very close to their host stars, much like Venus orbits close to the Sun. So, perhaps these exoplanets host surface liquid water as well!

Figure 2: A graphical representation of the possible climate history of Venus. For most of its history, it is proposed that Venus had a temperate climate with surface water.

The big picture: After analyzing the various models of Venusian history, scientists found that Venus was potentially habitable, like Earth is, for most of its lifetime, which is remarkably different from the acidic, scorching atmosphere we observe today. Large, simultaneous volcanic eruptions may have made it impossible for Venus to cool down, and the resultant dry and hot atmosphere could have led Venus to its current conditions. Even so, more observations from Venus’s surface are needed to fully understand its history and transformation.

Citation: Way, M. J. & Genio, A. D. D. Venusian Habitable Climate Scenarios: Modeling Venus Through Time and Applications to Slowly Rotating Venus-Like Exoplanets. Journal of Geophysical Research: Planets 125, e2019JE006276 (2020).

 

Rachel Kronyak, Planetary Geologist

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I work as a Systems Engineer at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. My job is very interdisciplinary but generally revolves around operating rover missions on Mars – the ultimate remote work experience! I’m involved in two Mars rover missions: the Curiosity rover and the Perseverance rover. Curiosity has been on Mars since 2012 and is still going strong! I help make decisions about what the rover is going to do, for example: where to drive to, what to take photos of, what to shoot the laser at. Being able to see brand-new, never-before-seen images of Mars is by far the best part of being on the Curiosity team!

 

The actual Perseverance rover undergoing final tests in the cleanroom at JPL. Image credit: NASA/JPL-Caltech/MSSS

The Perseverance rover is NASA’s latest Mars rover that is scheduled to launch THIS summer and land on Mars in February 2021. We are very busy making preparations for surface operations for when Perseverance lands on Mars. This involves a lot of rover hardware testing to figure out how the rover will drill and collect rock and regolith samples. We’re also busy training the science team to be able to operate the rover smoothly once it lands. To do this, we’ve had a few field training exercises to simulate the rover operations procedures. Rover teams are made up of hundreds of scientists and engineers from all over the world, so teamwork and communication are the most important factors in making NASA missions successful.

An artist’s rendition of what the Perseverance rover will look like once it lands on Mars. Image credit: NASA/JPL-Caltech/MSSS

Since we can’t send people to Mars just yet, sending car-sized rovers is the next best thing to help us get closer to answering fundamental questions about the Red Planet: Did Mars host environments that may have supported life in the past? Did life ever evolve on Mars? How has Mars’ climate evolved over time? What can the geologic rock record on Mars tell us about ancient environments and how they’ve changed over time? How can we prepare to send humans to Mars?

Simulating Mars rover operations in the desert and also with a fully functional Earth model of the Curiosity rover.
Me in the field – simulating Mars rover operations in the desert and also with a fully functional Earth model of the Curiosity rover.

I first became interested in science and NASA when I was in high school and had the opportunity to attend Space Camp in Huntsville, AL. A lifelong athlete, I really enjoy teamwork-oriented jobs, which is why jobs in mission operations have always appealed to me. My advice to young, aspiring scientists would be that if you find something that truly inspires you, pursue it! Meet new people, ask questions, and never stop exploring!

A photo of the countdown clock we have at JPL for Perseverance’s launch and landing. One of my favorite places at JPL.
The Curiosity rover in action on Mars, taking “selfies”. Image credit: NASA/JPL-Caltech/MSSS
The Curiosity rover in action on Mars, taking “selfies”. Image credit: NASA/JPL-Caltech/MSSS

Follow Rachel’s updates on her website, Twitter, or Instagram! Another website folks might be interested in: NASA’s Mars exploration website. It’s frequently updated with rover mission updates and has tons of info about past, present, and future missions to Mars: https://mars.nasa.gov/

Understanding the geologic history of a near-Earth Asteroid through the lens of NASA’s OSIRIS-Rex mission

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Craters, Boulders, and Regolith of (101955) Bennu Indicative of an Old and Dynamic Surface

by: K. J. Walsh, E. R. Jawin, R.-L. Ballouz, O. S. Barnouin, E. B. Bierhaus, H. C. Connolly Jr., J. L. Molaro, T. J. McCoy, M. Delbo’, C. M. Hartzell, M. Pajola, S. R. Schwartz, D. Trang, E. Asphaug, K. J. Becker, C. B. Beddingfield, C. A. Bennett, W. F. Bottke, K. N. Burke, B. C. Clark, M. G. Daly, D. N. DellaGiustina, J. P. Dworkin, C. M. Elder, D. R. Golish, A. R. Hildebrand, R. Malhotra, J. Marshall, P. Michel, M. C. Nolan, M. E. Perry, B. Rizk, A. Ryan, S. A. Sandford, D. J. Scheeres, H. C. M. Susorney, F. Thuillet, D. S. Lauretta and the OSIRIS-REx Team

Summarized by: Lisette Melendez

What data were used? Unlike geologic sites on Earth, scientists aren’t able to use field work to determine the geologic history of celestial objects like asteroids, planets, and distant moons. Instead, planetary geologists rely on data collected by scientific instruments on spacecraft, like cameras and spectrometers, to study these unreachable geologic features.

The data for this study was gathered from images taken by NASA’s ORISIS-Rex spacecraft, whose mission is to travel to a near-Earth asteroid named Bennu. Asteroids are the remains of the building blocks of our solar system that enabled the rise of planets and life, and most of them reside in the Main Asteroid Belt. However, sometimes asteroids are ejected and enter the inner solar system (i.e. the rocky planets: Mercury, Venus, Earth, and Mars), becoming near-Earth asteroids. This asteroid, Bennu, was chosen for the sample collection mission because of its proximity to Earth, large size (almost 500 meters long!), and carbonaceous (i.e., carbon-rich) composition. The carbon-rich part is important because these asteroids contain chemical compounds and amino acids that would have been present at the beginning of our Solar System. Even though the asteroid is relatively long compared to other asteroids, it’s only about as wide as the length of the Empire State Building!

The spacecraft is set to bring back a sample of this asteroid to Earth by 2023 for scientists to analyze. In late 2018, the spacecraft began the approach phase of the mission and used its cameras to take high-quality pictures of Bennu’s surface, as shown in Figure 1. These images are not only used to determine a good sample collection site, but scientists also use them to learn more about the geologic processes on Bennu’s surface. By weaving the images together, the team was able to produce a three-dimensional model of the asteroid and determine the location of boulders on the surface of Bennu. 

Figure 1: Shows the size of various boulders on Bennu’s surface. The arrows point towards identified fractures, which may be indicative of large impact events or stress caused by rapid temperature changes.

Methods: The surface of Bennu was mapped out by visually analyzing images taken by cameras on OSIRIS-Rex. Scientists combined image and radar data to measure the size and distribution of boulders on Bennu’s surface. By applying the same foundational geologic concepts observed here on Earth, scientists can draw conclusions about the geologic features on asteroids and what forces potentially formed them. 

Results: The orbit of a near-Earth asteroid is tumultuous, due to the possibility of collision with other asteroids and the forces exerted by Earth’s gravity, making a usual lifespan of a near-Earth asteroid only last around tens of millions of years. Usually, this would mean a young, consistently refreshed surface for these near-Earth asteroids. However, a detailed study of Bennu’s surface shows evidence of rocks that are hundreds of millions of years old – long before Bennu ever left the Main Asteroid Belt. 

Boulders are the most prominent geologic feature on Bennu’s surface. As shown in Figure 2, they can be found all around the asteroid. Scientists noted that the size of various boulders are simply too large for them to have been formed in Bennu’s current orbit, pointing towards the possibility they were created during larger asteroid collisions in the main asteroid belt. This indicates that studying the boulders further may aid in the understanding of Bennu’s parent body (i.e., where the rocks were originally created) and conditions in the main asteroid belt.

Another interesting result from the study is that even though the resolution of the images was not clear enough to depict fine-grained particles, the scientists measured thermal inertia (tendency to resist changes in temperature) and found that the results were consistent with the existence of fine-grained particles on Bennu’s surface. Come the end of 2020, the spacecraft will start up the TAGSAM (Touch-and-Go-Sample-Acquisition-Mechanism) instrument, blow nitrogen gas onto the surface to stir up dust, and collect the sample – leading to even more scientific discoveries on the asteroid front.  

Figure 2: Maps the abundance of boulders on Bennu’s surface, where red marks areas that are densely populated by boulders and blue marks areas where there are relatively less boulders.

Why is this study important? This study is a reminder of how fascinating geology is: scientists were able to predict the history of the asteroid solely by measuring the size and distribution of boulders on its surface. This group was able to differentiate between events that occurred while Bennu was in the Main Asteroid Belt versus a near-Earth orbit, which helps us understand the environment right outside of Earth and beyond. 

The big picture: By looking into the early Solar System, the data gathered in this study will help scientists understand the processes behind the formation of planets, as well as the origins of life. Additionally, the study will enhance our understanding of the evolution of near-Earth asteroids as well as the possibility of the asteroids impacting Earth.

Citation: Walsh, K.J., Jawin, E.R., Ballouz, R. et al. Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface. Nat. Geosci. 12, 242–246 (2019). https://doi.org/10.1038/s41561-019-0326-6

Lisette Melendez, Geology and Astronomy Undergraduate Student

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Standing outside of NASA Ames, where Lisette worked in aiding the lunar landing mission!

What is your favorite part of being a scientist?

Ever since I was very young, I’ve always had a fascination with geology. In elementary school, I would tout around my battered copy of the Smithsonian handbook on rocks and minerals and take notes in my “research journal”. Rocks littered every available surface of my room, and my ears always perked up when we finally reached the Earth Science section of our science classes. What’s cooler than learning about Earth’s layers and how volcanoes form? During field trips, I would sometimes get separated from the group, too mesmerized by rocks that I found on the ground. Even with all these signs, it wasn’t until the end of my first year in university that I realized that I could become a geologist and work with rocks for a career. 

I started off in a field that I was pressured into but that I had no passion for. How could I miss geology as a career option? For many years prior, every geologist that I encountered in my textbooks were white men. While I was working on one of my assignments, I looked over to see what my friend was working on. The assignment was to use Steno’s Laws of Stratigraphy to determine what order the rock layers were deposited. I thought the assignment was fascinating while my friend looked at me with a strange face. They told me about their professor, Dr. Sheffield, and how passionate she was for geology and all the amazing fieldwork she’s done throughout her career. This was a mindblowing moment for me: it was the first time I learned about a female geologist. That same day, I went to the student affairs office and changed my major to Geology. 

From that day forward, I got to experience first hand what a difference doing what you love made in one’s life. My favorite part of being a scientist is simply that there’s always more to learn. Every single day, I wake up incredibly excited to go to class and learn about minerals, volcanoes, and paleobiology. I still remember being in my old major looking wistfully at the Mineralogy class on the USF course inventory. I’m forever grateful that now, that’s what I study all the time! I look over my room and now there are textbooks on planetary volcanism, astrobiology, and sedimentology that join the rocks scattered on various surfaces. Sometimes, I feel like I never really changed from that child who loved rocks: now, I’m just working to be able to collect rocks for the rest of my life.

What do you do?

Right now, I’m studying geology and astronomy at the University of South Florida. My future goals are to get accepted into a PhD program for planetary science, and then hopefully work on the research team that analyzes samples from the surface of Mars and become a curator at a natural history museum! 

Most of the research I do works towards uncovering the geologic past of celestial objects. It’s the perfect overlap between my two favorite subjects: geology and astronomy! Last summer, I conducted research about Martian ice caps at Brown University through the Leadership Alliance – an awesome program aimed at increasing diversity in STEM (read my Time Scavengers post about it here!). I also interned at NASA, where I helped write the code of a navigation program that would assist scientists locate ideal landing areas on the Moon. This upcoming summer, I’m really excited to be working with the Smithsonian National Museum of Natural History on analyzing meteoritic samples collected by NASA’s OSIRIS-REx mission. The samples collected contain information on the earliest history of our solar system! I’m using my time in undergraduate studies to get a clearer idea of what branch of planetary science I’d like to delve into in graduate school.

Volunteering as a mentor for NCAS (NASA’s Community College Aerospace Scholars).

How does your research contribute to the understanding of climate change and the betterment of society in general?

I believe research in the planetary sciences helps humanity as a whole by illuminating our role in the universe. By addressing the questions of the universe,  the answers to our day to day problems become clearer through perspective. It’s easier to plot out humanity’s destiny and how to build a better society for everyone by figuring out where we came from and how the universe around us is changing. This is particularly important when considering the future of humans in space. Being able to find geologic analogs of celestial terrain (like the Martian surface) on Earth will help us decide which crops and structures work best for the Martian environment. As we continue exploring the universe, it’s important to keep in mind universal codes of safety, planetary preservation, and anti-imperialism in order to avoid harming the new environments we enter.

What methods do you use to engage your audience and community? What have you found to be the best way to communicate science?

One of the first pieces of advice that one of my mentors, Dr. Mustard, bestowed onto me was that “science is never done in a vacuum”. Collecting scientific data is an incredibly exciting part of research, but it’s also essential to communicate your findings with others to increase scientific literacy and humanity’s pool of knowledge. Science is all about sharing what you’ve learned and what you’ve experienced. It is much more rewarding involving different perspectives and helping everyone feel included. Through my officer positions at two clubs at USF, the Geology Club and the Contemporary Art Museum Club, I promote the importance of STEAM and interdisciplinary research. I believe one of the keys to successful science communication is to express why one’s excited about the topic and to make it relatable to what others are interested in. I’m really excited to join Time Scavengers as a science communications intern in order to hone in on this essential skill and become a better scientist overall.

Standing at the base of the 40 foot radio telescope at Green Bank Observatory!

What advice do you have for aspiring scientists?

My advice would be to just take a moment and think about what you really want from life. I’ve spent countless years just trying to follow what others expected me to do that I never really thought about what I wanted to be. Following the path others decide for you is no way to live your life. You’re the one who will have to live out your career path, so choose one you’re passionate in! There’s definitely space for you! There is such a wide range of fields, from studying bugs to glaciers, you deserve to make your mark the way that you want to.

Finding where you belong is essential to unlocking the zeal that will pull you through obstacles and challenges. Prior to joining the geology department, I was a very shy and reserved person. However, my passion for geology and astronomy (and the endless kindness from geologists) gave me the courage to overcome my anxieties and become resilient in the face of adversity. I transformed from a quiet and socially anxious person into the president of my university’s Geology Club and founder of USF’s Society of Women in Space Exploration Chapter. Openly doing what you love will also surround you with like-minded individuals that are the key to building a good support group! My favorite part about becoming a geologist would definitely be being able to network and meet others who are just as passionate about rocks as I am. It’s exhilarating, being friends with geologists and gathering around in the parking lot of a Waffle House to examine an outcrop. The feeling of togetherness is unmatched.

 

Fossil hunting—On Mars!

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Did you see this in the news? NASA is starting a new Mars mission, and this one has a very exciting goal: to find evidence of past life! And to study the habitability of Mars for past life and for humans in the future. 

A new rover, called Mars 2020 until a name is selected (update: Mars Perseverance Rover), will be sent to Mars this summer, with an arrival on Mars February 18, 2021. The rover will explore the Jezero crater for about one Martian year, equal to 687 Earth days. Jezero crater was chosen for study because there is evidence that this crater once contained a lake. 

Elevation map of Jezero Crater. Dark blue and purple are deeper areas, yellow is the highest. The circled area is the area of the mission. NASA/JPL-Caltech/MSSS/JHU-APL/ESA. https://photojournal.jpl.nasa.gov/catalog/PIA23511

Two rivers, on the left side of the picture, flowed into a crater. A flood like broke through the crater wall and allowed water to drain out of the crater (upper right). Inside of the crater is a former delta formed as sediments were deposited as the rivers entered the lakes and deposited sediment.  

Artist’s concept of the delta formed within the ancient lake. NASA/JPL-Caltech/University of Arizona, https://photojournal.jpl.nasa.gov/catalog/PIA22907

Spectral analyses of the deltas and fans have revealed the presence of carbonates and hydrated silicas.

Spectral analyses of the detlas and fans have revealed the presence of carbonates and hydrated silicas.

Carbonate is a chemical composed of carbon, oxygen, and a metal or hydrogen. For example, chalk, seashells, and egg shells are all made of calcium carbonate crystals (CaCO3). Carbonates need liquid water and an atmosphere with carbon dioxide to form. On Earth, carbonate rocks may be formed by the accumulation of tiny fossil shells, but carbonates can form abiotically (without life). Limestone, a carbonate rock, is a good preserver of body fossils and trace fossils. Silica, a combination of silicon and oxygen, forms in water. Chert and flint are examples of silica rocks. Chert is also formed by the accumulation of tiny shells, but these are made from silica, not carbonate.

Any fossils that are left on Mars from its warmer, wetter periods would likely be found in carbonate and silica deposits. Scientists expect that these fossils would be microorganisms (single celled organisms). 

In addition to searching for fossils, Mars 2020, Perseverance will also: 

  • Determine past climates that may have allowed ancient life to exist
  • Study the geology of Mars, including the processes that affected and altered Mars’s surface, as well as looking for rocks that formed in water and what they might reveal about past life
  • Help prepare for human explorers by studying radiation levels on Mars’s surface and chemicals common in martian soil that are known to be harmful to humans. 

This may be a very exciting mission, but the wait will be long! The search for fossils will be the last part of the mission. But we’ll keep you posted!

For more information, visit NASA’s about this mission: Mars 2020 Mission and Mars Perseverance Rover.