Planetary Science Institute

PRESS RELEASE: https://buff.ly/3MtwLTR The Martian polar caps are not created equally - here's why People have observed the bright Martian poles wax and wane for centuries, but only within the last 50 years have scientists discovered that they are mostly comprised of carbon dioxide cycling in and out of the atmosphere to the rhythm of the seasons. But exactly how this happens is a complex interplay of planetary processes that scientists are continually teasing out. Planetary Science Institute Senior Scientist Candice Hansen leads a new paper published in Icarus that weaves together decades of past research with more recent observations collected by the High-Resolution Imaging Experiment, or HiRISE, instrument on the Mars Reconnaissance Orbiter to compare how the Martian poles differ in their seasonal uptake and release of carbon dioxide. “Everybody knows there’s a difference in how carbon dioxide interacts with the poles, but how many people understand why?” Hansen said. “That was what I was setting out to describe. And fortunately, I have a whole bunch of really talented co-authors who were willing to fill in their own pieces.” The goal was to shed light on the processes that shape the planet’s surface as well as Mars’ overall climate – since Mars cycles about a quarter of its atmosphere throughout the Martian year. Like Earth, Mars spins at a tilt of about 25 degrees, so it experiences seasons, but Mars’ much longer path around the Sun is also more oblong – or what scientists call eccentric – than Earth’s. If Mars’ path around the Sun was a perfect circle, then all of its seasons would be equally long. But its eccentricity situates Mars farthest from the Sun during southern fall and winter – which is simultaneously northern spring and summer – meaning these seasons for each hemisphere are the longest for the planet. Mars’ southern hemisphere is also significantly more elevated than the northern hemisphere. “So ultimately, southern fall and winter bring the most freezing and lowest atmospheric pressure,” since so much of the atmosphere is frozen as dry ice, Hansen said. “These are the major drivers of differences in seasonal behavior of carbon dioxide between the hemispheres.” Mars’ northern winter, by contrast, is not only shorter than southern winter, but it also coincides with dust storm season. As a result, the northern polar seasonal cap contains a higher concentration of dust than the south polar cap, making the ice less robust. “They're not symmetric seasons,” Hansen said. Differences in the northern and southern polar terrains also impact how carbon dioxide ice and gas shape the landscape, according to the paper.

101 scientists, staff, board members, alumni and affiliates met Aug. 13-17 at the Hacienda Del Sol Guest Ranch Resort in Tucson for the Planetary Science Institute’s annual retreat. Learn more: https://buff.ly/477BynF

https://buff.ly/479bBDZ Frequently, it's the start of a journey, especially one into space, that generates the biggest impact. It isn't often that people remember how one ended. Mission planners decided to finish the Cassini research mission to Saturn by dropping the 12-ton spacecraft into a fiery death dive through the planet's atmosphere. It marked a surprisingly sentimental end to a flight that left scientists with an unexpected wealth of information about Saturn and its vast system of moons. One of the earliest motion pictures about Saturn featured photographs taken at Lowell Observatory near Flagstaff in the early 1950s. Forty-five years later, the ambition behind Cassini made it a mission with unusually high stakes: a 3.2 billion dollar trip to a world 800 million miles away, taking seven years to complete, requiring four gravity assisted course changes for a 12 ton spacecraft carrying more than a dozen scientific measurement packages. Amanda Hendrix with the Planetary Science Institute in Tucson describes it as a once-in-a-generation opportunity. "This was a mission to explore the Saturn system because all we had done before that was flybys of the whole system," said Hendrix. "And what we ended up launching was a really great spacecraft."

Meet our award-winning research scientist, Dr. Jamie Molaro! Dr. Jamie Molaro focuses on fracture processes and breakdown in rocky and icy material on airless bodies. She studies the role of thermally induced stresses in boulder disaggregation and regolith production. Dr. Molaro also studies ice sintering and the evolution of icy regolith on ocean worlds like Europa and Enceladus. She studies these processes from micro- to macroscopic scales, working to build an in-depth understanding of the role thermal forcing plays in surface evolution. She employs a combination of numerical modeling and laboratory experiments in this research, along with the occasional terrestrial field study. Dr. Molaro is a current Sample Science team member on NASA's OSIRIS-REx mission and a Co-I on the Project ESPRESSO node of the Solar System Exploration Research Virtual Institute (SSERVI). In her free time, she plays the harp, writes, makes stuff out of other stuff, and plays lots of D&D, board, and video games with her husband. Learn more: https://buff.ly/3X8A6Nj

Planetary Science Institute wishes everyone a restful, respectful Labor Day. Our offices are closed Friday, August 30, and Monday, September 2, to honor the holiday. We will open Monday, September 3, at 9am.

#JunoCam: Io Jupiter's innermost Galilean moon, Io, a volcanic world whose surface constantly changes, is seen in a processed image from NASA's Juno spacecraft. The photo was taken during the most recent perijove - or closest approach to Jupiter - of the spacecraft's extended mission. Credit: NASA / JPL-Caltech / SwRI / MSSS / Giuseppe Pappa Want to participate in citizen science and process JunoCam images? https://buff.ly/3eWoHuw

101 scientists, staff, board members, alumni, and affiliates met Aug. 13-17 at the Hacienda Del Sol Guest Ranch Resort in Tucson for the Planetary Science Institute’s annual retreat. PSI CEO and Director Mark Sykes said the gathering is intended to promote collaboration and camaraderie. This year, the retreat was extended by a day to accommodate presentations, Q&As, and casual conversations with the final four CEO candidates. The PSI board will weigh feedback from scientists and staff and present their selection of the next CEO in the fall. The CEO will take office at the end of 2025. Other sessions included updates from senior staff, scientific talks about ocean worlds, astrobiology, and open-source software, human resource talks about successful awareness conversations and ergonomics, communications and outreach talks, and new hire presentations and lightning talks on a range of topics. Evening activities included a reception, a soiree, a scotch tasting, a cowboy-themed night, and a banquet, which families were also invited to attend. More photos:

NASA’s Solar System Exploration Research Virtual Institute, or SSERVI, awarded PSI Research Scientist Jamie Molaro with the 2024 Susan Mahan Niebur Early Career Award. The award is given to an investigator who is within 10 years of receiving their doctorate and has made significant contributions to the exploration science communities. Molaro, who studies weathering and landscape evolution on airless icy and rocky bodies, spoke virtually to a crowd attending the award ceremony at Washington University in St. Louis on July 25 about how she tries to not let traditional expectations limit her work as a scientist. Molaro said she was feeling burnt out after an intense few years of research, so she sought out alternate ways to contribute to science and grow as a scientist. During this time, she founded a peer networking and support organization for Disabled scientists, called Disabled for Accessibility In Space, or DAIS. Through her work with DAIS she got involved with AstroAccess, where she led research to advance accessible design in space environments for future Disabled astronauts. Her passion for outreach started long ago. In 2013 she established The Art of Planetary Science, a public engagement effort to help people connect to science through art shows and workshops. “Efforts like AstroAccess and The Art of Planetary Science are about actively including non-academic and diverse voices and perspectives in space exploration,” she said. “And they make important contributions to the scientific community and society.” To other early-career scientists, she said, “Don’t let other people’s definition of science define how you do it or what makes you a scientist. The dimensionality that comes from experiences outside of traditional research will make you a better scientist.” Learn more: https://buff.ly/3T6Q8pI

Meet PSI Research Scientist Dr. Alexander Morgan. Dr. Alex Morgan is a geomorphologist interested in how planetary surfaces change with time. Most of his research centers on the history of water on Mars. Dr. Morgan grew up in the San Francisco Bay Area, spending much of his childhood in the open spaces of California. When he enrolled at UC Santa Cruz, geology seemed like an obvious choice for his major but switched his undergraduate program to planetary geology. He worked as a research associate at NASA Ames Research Center and the SETI Institute, received his Ph.D. at the University of Virginia, and became a predoctoral fellow at the Center for Earth and Planetary Studies at the Smithsonian Institution's National Air and Space Museum. Dr. Morgan joined PSI in 2020 and recently collaborated on a paper that describes, maps, and dates how glaciers and glacial runoff sculpted the northeastern rim of Mars’ Hellas basin over the last 3 billion years. Learn more: https://buff.ly/3Xexqic

Meet Planetary Science Institute Senior Scientist Dr. Alan Howard. Dr. Alan Howard’s research interests focus on the geomorphology of the Earth and other planetary bodies, including fluvial processes such as sediment transport, river incision, stream meandering, and alluvial fans. Dr. Howard’s studies have been applied to the Earth, the Moon, Mars, Europa, Callisto, Titan, minor satellites of Saturn, and Pluto. Techniques include geomorphic mapping using remote sensing and topographic information, quantitative modeling of long-term landform evolution, and statistical characterization of landforms. He incorporated much of his quantitative modeling work into the publicly available landform evolution model MARSSIM. Dr. Howard’s current planetary studies focus primarily on Mars and Pluto, including a recent paper that describes, maps, and dates how glaciers and glacial runoff sculpted the northeastern rim of Mars’ Hellas basin over the last 3 billion years. Learn more: https://buff.ly/3Xb057V