Tuesday, June 06, 2017

Sometimes I do Stick to These Topics...




A Pit Spotted On Mars Has Scientists Scratching Their Heads 
Marshall Shepherd ,  

I normally write about the weather and climate of Earth. I write about Earth's climate because as the American Meteorological Society reminds us in its statement on climate change

Prudence dictates extreme care in accounting for our relationship with the only planet known to be capable of sustaining human life

As a former NASA scientist, I am also fascinated by the weather and climate of our neighboring planets.  There are many lessons about Earth's climate provided by them. This weekend my attention was caught by a stunning new image of Mars released by NASA. As you look at the image, the obvious question is, "what is that large pit or depression?"

NASA
Before boring deeper into this question (and yes I was trying to be cute...."boring into the pit"....get it? Ok, I digress), I want to explore some of the other features in the image. The image is provided by NASA's Mars 

Reconnaissance Orbiter (MRO). According to NASA's website, MRO was launched in 2005 to search for evidence that water persisted on the surface of Mars for a long period of time. While other Mars missions have shown that water flowed across the surface in Mars' history, it remains a mystery whether water was ever around long enough to provide a habitat for life.

MRO has one of the largest cameras ever to fly on a planetary mission, which enables unprecedented looks at features on the surface of the planet (like the dust devil below). And if you want to check out something really cool, click this link for weekly weather reports and images from Mars provided by the Mars Color Imager (MARCI) on MRO. You are welcome!

NASA
Like Earth, Mars has polar ice caps. Unlike Earth, the polar ice caps on Mars are a combination of carbon dioxide and water ice. The University of Arizona's Phoenix Mars Mission website is a great source of information on Martian polar caps. The website notes

Carbon dioxide is an atmospheric gas made of one carbon atom and two oxygen atoms. In its frozen, solid state, carbon dioxide is known as dry ice. Rather than melting into liquid carbon dioxide, like water ice melts into liquid water, dry ice sublimates directly into carbon dioxide gas when the temperature reaches about -79 degrees C (-110 degrees F).

This is where things take a very different turn than Earth. During Martian summer, the carbon dioxide ice undergoes the process of sublimation (solid phase to vapor). During the winter, it becomes a solid again. Fall cloud cover starts the winter season ice cap growth.

The HI-RISE instrument on MRO took the image above during late summer season in the Martian Southern Hemisphere. The "swiss cheese" looking pattern shows the residual of bare surface and "dry ice." The low sun angle allows MRO to detect very detailed views of the surface topography and that strange "pit." One possibility is the pit is an impact crater. 

Things impact Mars, Earth, and the moon all of the time. A recent paper in Nature Geosciences documents some interesting details of the bombardment history of Mars. Another theory is that the depression may be a collapse pit.

There is no conclusive answer at this point on what it may be according to Lisa May, formerly Lead Program Executive for the Mars Exploration Program at NASA Headquarters. May is the founder and CEO of Murphian Consulting LLC. She provides planning, execution, and systems engineering services to clients ranging from tech startups to the UAE Space Agency. She messaged me the context of these fascinating missions.

Right now, there are six operating spacecraft in orbit around Mars—two from Europe, one from India, and three NASA ones. NASA’s most recent orbiter, MAVEN, was launched in 2013 to learn how Mars lost its atmosphere, and the European Space Agency’s Trace Gas Orbiter is currently aerobraking into its final orbit where it will study Mars’ atmospheric composition.
May also added the MRO has been sending stunning high-resolution images of Mars for over a decade, but she is quick to point out another part of its mission
Besides supporting Mars science, the images are used to select landing sites for rovers and landers.
Dr. Marshall Shepherd, Dir., Atmospheric Sciences Program/GA Athletic Assoc. Distinguished Professor (Univ of Georgia), Host, Weather Channel's Sunday Talk Show, Weather (Wx) Geeks, 2013 AMS President.