New research suggests the two types of streaks on Mars are caused by dry events
A Martian slope streak caused by a dust devil? From
data taken in 2023. Click for original image.
Scientists using a computer machine learning algorithm to assembly and analyze global maps of all known slope streaks and recurring slope lineae (RSL) — the two different types of streaks found on Mars whose cause as yet remain unexplained — have concluded that these streaks are likely caused by dry processes, not wet brine seeping from underground.
Slope streaks can occur randomly throughout the year, can be bright or dark, can occur anywhere, and fade with time. Recurring slope lineae instead appear seasonally in the same locations and are always dark.
You can read the published paper here. It essentially provides further details on research that was first announced at a conference in March. From its conclusion:
[O]ur observations suggest that slope streak and RSL formation may be predominantly controlled by two independent, dry drivers, 1) the seasonal delivery of dust onto topographic inclines, and 2) the spontaneous activation of accumulated dust by energetic triggers – wind and impacts for slope streaks, as well as dust devils and rockfalls for RSL.
…Our results underline the fundamental differences between slope streaks and RSL, despite their visual resemblance. Streak and RSL populations occur on opposite hemispheres (north vs south), at different topographic elevations (mostly lowlands vs mostly highlands), in opposite thermal inertia terrain (low vs high), in different wind speed regimes (above-average vs below-average), in dissimilar diurnal thermal amplitude and heat flux terrain (above-average vs average), in different WEH, H2O, H, and water vapor column terrain (average vs below-average), and in terrain that provides suitable (theoretical) conditions for liquid water at different seasons (Ls ~90° vs Ls ~ 270°).
This data suggests both types of streaks form in connection with very fine Martian dust, but the researchers also admit that the actual method in which these avalanche-type streaks form remains unclear. In both cases the streaks cause no change in the topography (sometimes even traveling uphill for short distances), produce no debris piles at their base, as avalanches typically do, and do not appear to have an obvious cause or source at the top of the streak.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
A Martian slope streak caused by a dust devil? From
data taken in 2023. Click for original image.
Scientists using a computer machine learning algorithm to assembly and analyze global maps of all known slope streaks and recurring slope lineae (RSL) — the two different types of streaks found on Mars whose cause as yet remain unexplained — have concluded that these streaks are likely caused by dry processes, not wet brine seeping from underground.
Slope streaks can occur randomly throughout the year, can be bright or dark, can occur anywhere, and fade with time. Recurring slope lineae instead appear seasonally in the same locations and are always dark.
You can read the published paper here. It essentially provides further details on research that was first announced at a conference in March. From its conclusion:
[O]ur observations suggest that slope streak and RSL formation may be predominantly controlled by two independent, dry drivers, 1) the seasonal delivery of dust onto topographic inclines, and 2) the spontaneous activation of accumulated dust by energetic triggers – wind and impacts for slope streaks, as well as dust devils and rockfalls for RSL.
…Our results underline the fundamental differences between slope streaks and RSL, despite their visual resemblance. Streak and RSL populations occur on opposite hemispheres (north vs south), at different topographic elevations (mostly lowlands vs mostly highlands), in opposite thermal inertia terrain (low vs high), in different wind speed regimes (above-average vs below-average), in dissimilar diurnal thermal amplitude and heat flux terrain (above-average vs average), in different WEH, H2O, H, and water vapor column terrain (average vs below-average), and in terrain that provides suitable (theoretical) conditions for liquid water at different seasons (Ls ~90° vs Ls ~ 270°).
This data suggests both types of streaks form in connection with very fine Martian dust, but the researchers also admit that the actual method in which these avalanche-type streaks form remains unclear. In both cases the streaks cause no change in the topography (sometimes even traveling uphill for short distances), produce no debris piles at their base, as avalanches typically do, and do not appear to have an obvious cause or source at the top of the streak.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
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