• Mounds of ice in craters give new insigh

    From ScienceDaily@1:317/3 to All on Tue Mar 29 22:30:40 2022
    Mounds of ice in craters give new insight into Mars' past climate
    Honing the ways Mars' orbit and orientation impacted climate over time
    can help scientists find periods of potential habitability

    Date:
    March 29, 2022
    Source:
    American Geophysical Union
    Summary:
    Newly discovered deposits of layered ice in craters scattered
    around Mars' southern hemisphere provide insights into how the
    planet's orientation controlled the planet's climate over the
    past 4 million years, according to a new study. The findings help
    scientists understand what controlled Mars' past climate, which is
    essential for predicting when the planet could have been habitable.



    FULL STORY ========================================================================== Newly discovered deposits of layered ice in craters scattered around Mars' southern hemisphere provide insights into how the planet's orientation controlled the planet's climate over the past 4 million years, according
    to a new study. The findings help scientists understand what controlled
    Mars' past climate, which is essential for predicting when the planet
    could have been habitable.


    ==========================================================================
    The study was published in the AGU journal Geophysical Research Letters,
    which publishes short-format, high-impact research with implications
    spanning the Earth and space sciences.

    Ice deposits on Mars reflect a combination of temperature, hydrology and planetary dynamics, as they do on Earth. The planet's tilt and orbit
    impact temperature and sunlight on the surface, which contribute to
    climate. Thicker, more pure ice layers generally reflect cold periods
    with more ice accumulation, while thin, dusty layers were likely warmer
    and less able to build up ice.

    The new study matches these ice layers to the tilt of Mars' axis and its orbital precession, or how the planet's elliptical orbit rotates around
    the sun over time, with unprecedented resolution and confidence.

    The findings give scientists insight into how Mars' climate has changed
    over time. While the study is limited to the recent past, establishing
    these climate-orbit relationships helps scientists understand Martian
    climate deeper in the past, which could help pinpoint periods of potential habitability.

    "It was unexpected how cleanly those patterns matched to the orbital
    cycles," said lead study author Michael Sori, a planetary scientist at
    Purdue University. "It was just such a perfect match, as good as you
    can ask for." From caps to craters


    ========================================================================== Previously, Martian climate scientists have focused on polar ice caps,
    which span hundreds of kilometers. But these deposits are old and may
    have lost ice over time, losing fine details that are necessary to
    confidently establish connections between the planet's orientation and
    motion and its climate.

    Sori and his colleagues turned to ice mounds in craters, just tens of kilometers wide but much fresher and potentially less complicated. After scouring much of the southern hemisphere, they pinpointed Burroughs
    crater, 74 kilometers wide, that has "exceptionally well-preserved"
    layers visible from NASA HiRISE imagery, Sori said.

    The researchers analyzed the layers' thicknesses and shapes and found
    they had strikingly similar patterns to two important Martian orbital
    dynamics, the tilt of Mars' axis and orbital precession, over the last
    4 to 5 million years.

    The findings improve on previous research, which used Mars' polar ice
    records of climate to establish tentative connections to orbit. But
    those records were too "noisy," or complicated, to confidently connect
    the two. Younger, cleaner crater ice preserves less complicated climate records, which the researchers used to match climate changes to orbital precession and tilt with a high level of precision.

    Mars as a natural lab Discerning the connections between orbital cycles
    and climate is important for understanding both Martian history and
    complex climate dynamics on Earth. "Mars is a natural laboratory for
    studying orbital controls on climate," Sori said, because many of the complicating factors that exist on Earth -- biology, tectonics -- are negligible on Mars. The whole planet, in essence, isolates the variable
    for scientists.



    ==========================================================================
    "If we're ever going to understand climate, we need to go to places that
    don't have these interfering factors," said Isaac Smith, a planetary
    scientist at the Planetary Science Institute and York University who
    was not involved in the study. In that sense, "Mars is a pristine
    planet. And there are a lot of potential applications here. Mars has
    a lot more in common with Pluto and Triton than you think." Not all
    smaller ice deposits have clean, exposed layers at their surface. Some
    might be hidden inside the mounds. Eventually, Sori said, the goal is to
    sample ice cores like scientists do on Earth, but Mars rovers don't have
    that capability yet. Instead, scientists can use ground-penetrating radar
    data to "peer inside" the ice and check for layers, making sure visible
    layers extend throughout the deposit. It's a necessary quality-control
    step in the present study, and the method may help future explorations
    of Martian ice without layers visible at the surface.

    "Being able to pull a climate signal from a small ice deposit is a
    really cool result," said Riley McGlasson, a study co-author from Purdue University who applied this method in the new study. "With radar, we
    can get closer to the full story. That's why I'm excited to take this
    a step further in the future."

    ========================================================================== Story Source: Materials provided by American_Geophysical_Union. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Michael M. Sori, Patricio Becerra, Jonathan Bapst, Shane Byrne,
    Riley A.

    McGlasson. Orbital Forcing of Martian Climate Revealed in a South
    Polar Outlier Ice Deposit. Geophysical Research Letters, 2022; 49
    (6) DOI: 10.1029/2021GL097450 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220329142530.htm

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