(ORDO NEWS) — Another Martian mystery. Mars is truly an amazing planet. Long thought to be barren and dead, the red planet has proven otherwise thanks to numerous flights to its surface in the last decade.
Through missions such as InSight, Perseverance, Curiosity, Odyssey and various others, we are beginning to understand the real side of Mars.
Data collected by NASA’s Mars Oddysey mission reveals some of Mars’ secrets. For example, data obtained by the Odyssey may finally help explain why dust avalanches appear on the slopes of Mars and why Martian frost seems invisible to the eye.
Earlier this year, NASA’s Mars Odyssey orbiter took pictures of the Martian surface at dawn, leaving scientists somewhat confused.
They observed the surface of the red planet in visible light, the light that the human eye perceives, and noticed a strange blue-whitish morning that lit up when the Sun rose on the horizon.
They wanted to see if there was something more, and using the Odyssey’s heat-sensitive camera, they noticed that frost was widespread and present even in regions where it was not visible.
It was a puzzle to be solved.
In this case, they studied frost, which forms overnight and is made up primarily of carbon dioxide—essentially dry ice that often appears on Mars as frost instead of water ice.
But the mystery that remained unanswered was why dry ice frost was evident in some regions but invisible in others.
Solving the mystery
A paper published in the Journal of Geophysical Research: Planets may have the answer.
Experts have offered an explanation that could also explain how planet-shaping dust avalanches come down after sunrise.
The rarefied atmosphere of Mars (the density is only 1% of the Earth’s) allows the Sun to quickly heat the frost that forms during the night. Within minutes, dry ice evaporates into the atmosphere instead of melting.
In many places where frost is not visible on the surface of the red planet, Lucas Lange, an intern working with Pico, first discovered its cold-temperature signature.
Temperature changes were present just a few microns below the surface.
“Our first thought was that there might be ice buried there,” Lange said in an article published by NASA.
“Dry ice is abundant near the poles of Mars, but we were looking closer to the planet’s equator, which is usually too warm for dry ice to frost,” he added.
Dirty, dirty frost
In their study, the scientists explain that what we see is “dirty rime” – a mixture of dry ice rime with dust particles that make it appear in visible light but not in infrared.
This led scientists to believe that dirty frost could also be responsible for the dark-colored streaks that run along the slopes of Mars. Dust avalanches are reshaping mountain ranges across the planet, resulting in bands.
They probably resemble a river of dust rushing towards the ground and throwing out fluffy material. Over the course of several hours, the dust is blown down, revealing bands of darker material at the bottom.
The dark streaks seen in some images of Mars are different from the repetitive slope lines that appear over the course of weeks (not hours) year after year in the same places. According to the scientific community, the repeated slope lines are caused by sand or dust flows, not salt water.
In their recent study, the authors found that slope stripes are more common in areas that experience morning frost. Scientists believe the streaks were caused by evaporating frost, which created enough pressure to loosen the dust grains, causing avalanches.
Mars Odyssey is the longest continuously operating spacecraft in orbit around a planet other than Earth.
Mars Odyssey has been orbiting the red planet since October 2001. The primary purpose of the spacecraft is to study the Martian environment and provide vital information about possible hazards to future Mars explorers.
The Odyssey mission also aims to map the chemical and mineralogical composition of Mars to find evidence of past or present water and volcanic activity on Mars.
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