Martian surface frost, comprised mostly of co2, appears bluish-white in these images from the Thermal Emission Imaging System (THEMIS) cam aboard NASAs 2001 Odyssey orbiter. THEMIS takes images in both visible light, perceptible to the human eye, and heat-sensitive infrared. Credit: NASA/JPL-Caltech/ASU
A brand-new research study using information from NASAs Mars Odyssey orbiter may explain why Martian frost can be unnoticeable to the naked eye and why dust avalanches appear on some slopes.
In 2015, scientists were astonished after examining photographs of the Martian landscape acquired at dawn by NASAs Mars Odyssey orbiter. They might see ghostly, blue-white early morning frost illuminated by the increasing Sun when they peered at the surface with visible light– the sort that the human eye senses. When the orbiters heat-sensitive cam was utilized, the ice appeared more extensively, consisting of in places where none was formerly observed.
The researchers knew they were looking at frost that forms overnight and is largely formed of carbon dioxide– basically, solidified carbon dioxide, which frequently looks like frost on the Red Planet instead of as water ice. Why was this dry ice frost visible in some locations and not others?
Martian surface frost, made up largely of carbon dioxide, appears bluish-white in these images from the Thermal Emission Imaging System (THEMIS) electronic camera aboard NASAs 2001 Odyssey orbiter. They could see ghostly, blue-white morning frost lit up by the increasing Sun when they peered at the surface area with noticeable light– the sort that the human eye senses. These dark streaks, also understood as “slope streaks,” resulted from dust avalanches on Mars. These dark streaks, also understood as “slope streaks,” resulted from dust avalanches in a location of Mars called Acheron Fossae. The phenomenon led the scientists to believe filthy frost might also explain some of the dark streaks that can extend 3,300 feet (1,000 meters) or more down Martian slopes.
In a paper released recently in the Journal of Geophysical Research: Planets, these researchers proposed a surprising answer that might likewise explain how dust avalanches, which are reshaping the world, are triggered after dawn.
These dark streaks, also understood as “slope streaks,” arised from dust avalanches on Mars. The HiRISE electronic camera aboard NASAs Mars Reconnaissance Orbiter caught them on December 26, 2017. Credit: NASA/JPL-Caltech/UArizona
From Frost to Vapor
Introduced in 2001, Odyssey is NASAs longest-lived Mars mission and brings the Thermal Emission Imaging System (THEMIS), an infrared, or temperature-sensitive, cam that offers an one-of-a-kind view of the Martian surface. Odysseys existing orbit offers a special look at the planet at 7 a.m. local Mars time.
” Odysseys early morning orbit produces spectacular pictures,” said Sylvain Piqueux of NASAs Jet Propulsion Laboratory in Southern California, who led the paper. “We can see the long shadows of dawn as they stretch throughout the surface area.”
Because Mars has so little atmosphere (simply 1% the density of Earths), the Sun rapidly warms frost that develops overnight. Instead of melting, dry ice vaporizes into the atmosphere within minutes.
Lucas Lange, a JPL intern dealing with Piqueux, first noticed the cold-temperature signature of frost in lots of locations where it could not be seen on the surface area. These temperature levels were appearing simply 10s of microns underground– less than the width of a human hair “below” the surface area.
These dark streaks, also called “slope streaks,” resulted from dust avalanches in an area of Mars called Acheron Fossae. The HiRISE electronic camera aboard NASAs Mars Reconnaissance Orbiter recorded them on December 3, 2006. Credit: NASA/JPL-Caltech/UArizona
” Our very first idea was ice could be buried there,” Lange stated. “Dry ice abounds near Mars poles, however we were looking closer to the equator of the world, where its typically too warm for solidified carbon dioxide frost to form.”
In their paper, the authors propose they were seeing “filthy frost”– solidified carbon dioxide frost blended with fine grains of dust that obscured it in visible light but not in infrared images.
Defrosting Frost and Avalanches
The phenomenon led the scientists to think unclean frost might likewise describe some of the dark streaks that can stretch 3,300 feet (1,000 meters) or more down Martian slopes. They understood the streaks resulted from, essentially, dust avalanches that gradually improve mountainsides throughout the planet.
These dark streaks are not the like a better-documented range called repeating slope lineae, which repeat in the exact same locations, season after season, for weeks (rather of hours) at a time. Once believed to arise from briny water gradually seeping from mountainsides, repeating slope lineae are now generally believed to result from flows of dry sand or dust.
Mapping the slopes streaks for their current study, the authors discovered they tend to appear in locations with early morning frost. The scientists propose the streaks arised from the vaporizing frost developing just adequate pressure to loosen up the dust grains, triggering an avalanche.
The hypotheses are additional evidence of simply how unexpected the Red Planet can be.
” Every time we send out an objective to Mars, we discover exotic brand-new processes,” said Chris Edwards, a paper co-author at Northern Arizona University in Flagstaff. “We do not have anything precisely like a slope streak in the world. You need to believe beyond your experiences on Earth to comprehend Mars.”
Referral: “Gardening of the Martian Regolith by Diurnal CO2 Frost and the Formation of Slope Streaks” by L. Lange, S. Piqueux, C. S. Edwards, 27 March 2022, Journal of Geophysical Research: Planets.DOI: 10.1029/ 2021JE006988.
More About the Mission.
JPL handles the 2001 Mars Odyssey mission for NASAs Science Mission Directorate in Washington. Lockheed Martin Space in Denver is the prime specialist for the Odyssey project and developed and constructed the orbiter.