Millions of mysterious black streaks littered throughout the floor of Mars have puzzled scientists for many years, however now researchers could lastly have a correct clarification. The new idea additionally explains why it has taken so lengthy to resolve this specific downside.
Martian “slope streaks” are darkish albedo options that cowl the slopes of topographical options throughout the Red Planet. They had been found within the Nineteen Seventies, and scientists initially assumed they had been proof of landslides brought on by melting ice. But whereas scientists nonetheless suppose that the streaks are the results of landslides, a examine printed in May revealed that these landslides are literally triggered by “dry processes” that don’t contain any water. This narrowed down the record of potential causes however didn’t conclusively settle the controversy across the streaks’ origins.
One of the most famous examples of these streaks is on Apollinaris Mons — an extinct shield volcano located just south of Mars’ equator. Here, hundreds of parallel streaks can be seen on a single side of a large ridge, giving the structure a “barcode-like” appearance (see below). These streaks appeared at some point between 2013 and 2017, and scientists later realized that they were the result of a nearby meteoroid impact, Live Science’s sister site Space.com reported.
As a outcome, some researchers assumed that meteoroid impacts and different seismic occasions, equivalent to marsquakes, are accountable for birthing most slope streaks. But a brand new examine, printed Nov. 6 within the journal Nature Communications, means that this isn’t the case.
Instead, an evaluation of round 2.1 million slope streaks, photographed by NASA’s Mars Reconnaissance Orbiter between 2006 and 2024, revealed that the majority new streaks are the results of seasonal wind and dirt erosion. (The examine estimates the full variety of slope streaks on Mars to be round 1.6 million, however some streaks had been included in a number of picture units.)
“Dust, wind and sand dynamics appear to be the main seasonal drivers of slope streak formation,” the examine’s sole creator Valentin Bickel, a planetary scientist on the University of Bern in Switzerland who additionally co-authored the May examine, stated in a statement. “Meteoroid impacts and quakes seem to be locally distinct, yet globally relatively insignificant drivers [of streak formation],” he added.
Bickel estimates that lower than 0.1% of newly fashioned slope streaks are created by meteoroid impacts or marsquakes.
Bickel’s evaluation confirmed that slope streaks are grouped into 5 key areas throughout Mars, and that new streaks kind in every of those areas when seasonal wind speeds are highest and exceed the edge for “dust mobilization.” Once this threshold has been surpassed, landslides can extra simply happen in that space, Bickel added.
This course of is much like how excessive winds can choose up Martian mud and set off sizable tornadoes, or “dust devils,” on the Red Planet’s wide-open plains.
The cause it has taken scientists so lengthy to resolve this puzzle is probably going as a result of all of it occurs underneath the duvet of darkness. “The conditions most conducive to seasonal streak formation appear to occur at sunrise and sunset, explaining the lack of direct observations of streak-forming events to date,” Bickel wrote within the examine.
The examine additionally revealed that slope streak formation seemingly happens at an annual charge of round 0.05 new streaks per current streak. Given that there are estimated to be 1.6 million slope streaks, meaning the present charge of formation is round 80,000 new streaks per 12 months. Most streaks seemingly final for a number of many years earlier than disappearing, however there may be not sufficient orbiter information to inform for certain.
While slope streaks cowl lower than 0.1% of Mars’ floor, the brand new examine means that they would be the largest single contributor to atmospheric mud. Therefore, higher understanding the streaks’ function within the Martian mud cycle, which might affect future human colonies on Mars, needs to be a key objective for future Mars missions.
“These observations could lead to a better understanding of what happens on Mars today,” Colin Wilson, the European Space Agency’s mission scientist for the ExoMars Trace Gas Orbiter, who was not concerned within the new examine, stated within the assertion. “Obtaining long-term, continuous and global-scale observations that reveal a dynamic Mars is a key objective of present and future orbiters.”