Martian experts have known since 2011 that mysterious, possibly water-related streaks appear and disappear on the planet’s surface. Georgia Institute of Technology Ph.D. candidate Lujendra Ojha discovered them while an undergraduate at the University of Arizona.
Dark flow like features called Recurring Slope Lineae emanating from bedrock exposures at Palikir crater on Mars during southern summer. These flows are observed to form and grow during warm seasons when surface temperature is hot enough for salty ice to melt, and fade or completely disappear in cold season. Arrows point to bright, smooth fans left behind by flows.
These features were given the descriptive name of recurring slope lineae (RSL) because of their shape, annual reappearance and occurrence generally on steep slopes such as crater walls. Ojha has been taking a closer look at this phenomenon, searching for minerals that RSL might leave in their wake, to try to understand the nature of these features: water-related or not?
Ojha and Georgia Tech Assistant Professor James Wray looked at 13 confirmed RSL sites using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) images. They didn’t find any spectral signature tied to water or salts. But they did find distinct and consistent spectral signatures of ferric and ferrous minerals at most of the sites. The minerals were more abundant or featured distinct grain sizes in RSL-related materials as compared to non-RSL slopes.
“We still don’t have a smoking gun for existence of water in RSL, although we’re not sure how this process would take place without water,” said Ojha. “Just like the RSL themselves, the strength of the spectral signatures varies according to the seasons. The signatures are stronger when it’s warmer and less significant when it’s colder.”
The research team also notes that the lack of water-related absorptions rules out hydrated salts as a spectrally dominant phase on RSL slopes. For example, ferric sulfates have been found elsewhere on Mars and are a potent antifreeze. If such salts are present in RSL, then they must be dehydrated considerably under exposure to the planet’s conditions by the time CRISM observes them in the mid-afternoon.
The findings were recently published in Geophysical Research Letters, and the Georgia Tech duo’s newest paper, published in the journal Icarus, indicates that predicting where RSL will appear is, at best, a guessing game.
Ojha, Wray, and several Arizona-based colleagues looked at every image gathered by the High Resolution Imaging Science Experiment (HiRISE) from March to October of 2011. They hunted for areas that were ideal locations for RSL formation: areas near the southern mid-latitudes on rocky cliffs. They found 200, but barely any of them had RSL.
“Only 13 of the 200 locations had confirmed RSL,” said Ojha. “There were significant differences in abundance and size between sites, indicating that additional unknown factors such as availability of water or salts may play a crucial role in RSL formation.”
Comparing their new observations with images taken in previous years, the team also found that RSL are much more abundant some years than others. Water on Mars today seems elusive at best – there one year, gone the next.
“NASA likes to ‘follow the water’ in exploring the red planet, so we’d like to know in advance when and where it will appear,” Wray said. “RSL have rekindled our hope of accessing modern water, but forecasting wet conditions remains a challenge.”
Ojha and Wray are also among several co-authors on another RSL-related paper published this month in Nature Geoscience. That study, led by the University of Arizona’s Alfred McEwen, found some RSL in Valles Marineris, near the Martian equator.
Jason Maderer | EurekAlert!
PR of MCC: Carbon removal from atmosphere unavoidable for 1.5 degree target
22.05.2018 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH
Monitoring lava lake levels in Congo volcano
16.05.2018 | Seismological Society of America
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
22.05.2018 | Life Sciences
22.05.2018 | Earth Sciences
22.05.2018 | Trade Fair News