An image of the Terra Sirenum region’s gullies on Mars has been captured by the High Resolution Imaging Science Experiment (HiRISE) camera on board NASA’s Mars Reconnaissance Orbiter. Credit goes to NASA/JPL/University of Arizona.
A new research project has delved into the explanation of how Martian craters’ gullies may have originated from sporadic intervals of meltwater arising from ice present both on and beneath the planet’s surface.
Researchers from Brown University have spearheaded a study that has illuminated the potential recent role that water from thawing ice might have played in creating ravine-like channels along the flanks of impact craters on the Martian surface.
As recently divulged in the esteemed journal Science, the study’s focal point is Martian gullies. These gullies bear an uncanny resemblance to those in Earth’s Antarctic Dry Valleys, which result from the erosion of water from glacial melting. The team of scientists, with the inclusion of Brown’s planetary scientist Jim Head, constructed a model to discern the optimal conditions on Mars for it to heat above freezing, consequently causing intermittent phases of liquid water due to the melting of surface and subsurface ice.
The team made the discovery that when Mars’ axis inclines to 35 degrees, the atmospheric density is adequate to allow short-lived melting events at gully sites. They aligned the data from their model to specific eras in Martian history when rapid expansion of gullies in the Terra Sirenum region is hypothesized to have transpired, descending from elevated points — a process inexplicable without intermittent water presence.
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Historical Context and Conclusions
Head, a geological sciences professor at Brown, noted that though Mars harbored running water, valley networks, and lakes early in its history, around 3 billion years ago all liquid water disappeared, leaving Mars as a hyper-arid or polar desert. The current research illustrates that even following this transformation, Mars’ 35-degree axis tilt allowed temperatures to rise sufficiently to melt snow and ice, temporarily reintroducing liquid water before re-freezing.
This research aids in bridging gaps in our understanding of gully formation, encompassing factors like starting elevation, erosion severity, and extension down crater sides.
Contrasting With Prior Theories
Earlier hypotheses proposed that Martian gullies were shaped by carbon dioxide frost, which sublimates, triggering rocks and debris to cascade down slopes. The gullies’ stature led many to conjecture that glacial meltwater must have been a factor, given the distance traversed and their eroded appearance. Establishing the existence of liquid water on Mars since its disappearance has been challenging due to persistently low temperatures.
The current study infers that the genesis of gullies was steered by intermittent ice melting and by CO2 frost evaporation at different times of the year. This phenomenon has probably reoccurred for millions of years, with the last known occurrence around 630,000 years ago.
The research reveals that should ice be present at gully locations when Mars tilts to about 35 degrees, conditions would be appropriate for melting, as temperatures would climb above 273 degrees Kelvin (about 32 degrees Fahrenheit).
Implications and Potential Impact
Jay Dickson, the study’s primary author and now a researcher at the California Institute of Technology, stated that the global distribution of gullies is more coherently explained by liquid water over the past million years. He emphasized that water explains the elevation distribution of gullies in ways that CO2 cannot, signifying that Mars has been capable of generating liquid water in volumes sufficient to erode channels within the last million years, a relatively recent time frame in Martian geological terms.
Despite skepticism surrounding the meltwater hypothesis and difficulties modeling correct conditions on Mars for ice melting, the team was persuaded of the meltwater theory’s accuracy due to observed analogous features in Antarctica. There, even amidst frigid temperatures, solar heat allows ice to melt, leading to gully formation.
The new research continues the legacy of earlier work on Martian gullies. For example, a 2015 study from the team indicated the possibility of past water availability for gully formation, contingent upon Mars’ axis tilt. This spurred them to model the tilt and correspond it with the locations and altitudes of formed gullies.
Possibility of Life and Prospects for Exploration
The paper reignites the intrinsic question of potential life existence on Mars, given that Earth’s life is intrinsically linked to liquid water’s presence. Mars will inevitably tilt to 35 degrees again, researchers believe.
Head posed the question, “Is there a bridge, so to speak, between the initial warm and wet Mars and today’s Mars in terms of liquid water?” He emphasized the quest to find environments conducive to life’s origin, preservation, and continuation, and drew a parallel with Earth’s frigid Antarctic environment where scarce organisms exist in stasis, awaiting water.
The study also highlights the significance of these gullies as possible future exploration targets on Mars.
Reference: “Gullies on Mars could have formed by melting of water ice during periods of high obliquity” by J. L. Dickson, A. M. Palumbo, J. W. Head, L. Kerber, C. I. Fassett, and M. A. Kreslavsky, 29 June 2023, Science. DOI: 10.1126/science.abk2464
Funding for this study was provided by NASA’s Mars Data Analysis Program. Other affiliated authors from Brown include former graduate students Ashley Palumbo and Laura Kerber, ex-graduate student and postdoctoral researcher Caleb Fassett, and visiting researcher Mikhail Kreslavsky, a planetary scientist at the University of California, Santa Cruz.
Frequently Asked Questions (FAQs) about Martian Gullies
What is the main subject of the study concerning Mars?
The study focuses on understanding how gullies on Martian craters could have formed by on-and-off periods of meltwater from ice on and beneath the surface of Mars. It explores the recent role that water from melting ice might have played in creating ravine-like channels on Mars and compares this with previous theories about gully formation.
Who conducted the research on Martian gullies?
The research was led by Brown University researchers, including planetary scientist Jim Head. Collaborators in the study include researchers from California Institute of Technology and the University of California, Santa Cruz.
What are the implications of the study for the understanding of Martian gullies?
The study suggests that Martian gullies were shaped by intermittent ice melting, possibly in combination with CO2 frost evaporation. The research highlights that these phenomena have likely occurred repeatedly over millions of years and that Mars has been capable of generating liquid water sufficient to erode channels in its recent geological history.
How do Martian gullies compare to features on Earth?
Martian gullies bear a resemblance to gullies that form on Earth, specifically in the Dry Valleys of Antarctica. These terrestrial gullies are caused by water erosion from melting glaciers, a process that helped inform the study’s exploration of similar features on Mars.
Could the study’s findings have any implications for life on Mars?
Yes, the paper raises the question of whether life could exist on Mars, as life on Earth is closely associated with the presence of liquid water. The study’s findings that water might exist intermittently on Mars may open up new discussions about the possibility of microbial life surviving on the planet.
What does the study say about future exploration missions on Mars?
The study emphasizes the importance of the gullies as potential targets to visit during future exploration missions on Mars. Understanding the formation and presence of these gullies could aid in selecting locations for further study and exploration.
How does the new study relate to previous theories about Martian gullies?
Previous theories mainly proposed that Martian gullies were carved by carbon dioxide frost. The new study, however, suggests that gully formation was more likely driven by periods of melting ice and CO2 frost evaporation. It provides a more detailed understanding, incorporating temperature changes and Mars’ axial tilt to explain gully formation, a concept that was previously difficult to prove.
How recent are the phenomena studied in Martian gullies?
The research found that the phenomena related to gully formation have likely occurred repeatedly over the past several million years, with the most recent occurrence estimated to be around 630,000 years ago. This is considered very recent in the context of Mars’ geological history.
What is the significance of Mars’ axis tilting to 35 degrees?
When Mars tilts on its axis to 35 degrees, the atmosphere becomes dense enough for brief episodes of melting to occur at gully locations. This inclination allows temperatures to rise sufficiently to melt snow and ice, leading to periods of liquid water on Mars, which could have contributed to gully formation.
More about Martian Gullies
- Mars Reconnaissance Orbiter
- High Resolution Imaging Science Experiment (HiRISE)
- Brown University Planetary Geosciences Group
- NASA Mars Exploration
- Science Journal
6 comments
the study’s pretty comprehensive, but what if other factors are involved in gully formation that we havnt studied yet? Shouldn’t we be more cautious in our conclusions?
The information about Mars’ axis tilting to 35 degrees and causing melting is new to me. How often does this happen, and what other effects might it have on the Martian surface? Theres a lot to unpack here.
So if there’s water on Mars, does that mean we can find life there too? This is an exciting study, cant wait to see what comes next.
Amazing insights in this research! I’m curious about the comparison with the Antarctic dry valleys, how closely does Mars match these earth formations?
Finally some solid evidence on the gullies on mars. These Brown University guys are really pushing the boundaries. Maybe life on Mars isnt just science fiction, huh?
Can’t believe how much Mars resembles earth in some aspects. Meltwater on Mars? Never though that possible, its a huge breakthrough I guess.