New Planet Four: Ridges Search

Today we have a guest blog by JPL research scientist Laura Kerber,  our lead researcher on Planet Four: Ridges. Laura studies  physical volcanology, aeolian geomorphology, wind over complex surfaces, and the ancient Martian climate.

Greetings to you in these apocalyptic times! I hope that you and your families are doing well in isolation, or wherever you find yourselves to be.

 Over the last few years, Planet Four: Ridges has ranged far and wide across the Arabia Terra, from Nili Fossae near the future landing site of the Mars 2020 Perseverance rover, all the way to the plains of Meridiani Planum, near where little Opportunity lost its life in a 2018 global dust storm after 15 beautiful years of adventure. Along the way, you all have discovered many other treasures, including polygonal fracture networks, networks of dark lines, patches of desiccation polygons (mud-cracks) and many other fascinating features, each of which could seed a study of its own.

Your polygonal ridge discoveries are now being incorporated into a journal article, which has been undergoing many iterations as we prepare it for submission.

In the meantime, thanks to hard work by Meg Schwamb and Michael Aye, a new part of Meridiani has been opened up to us to search, just to the east of where we had been looking:

Figure 1. The broad region of study. The aquamarine dots are where you found Meridiani ridges in the last campaign. The turquoise squares are the footprints of the images that we’ll be looking through this time. The orange line is the fictional traverse of Mark Watney in the novel “The Martian” by Andy Weir. The yellow star is the location of the Opportunity rover. The background is from the Mars Orbiting Laser Altimeter, which gives us topography (blue is low and red is high).

On our last foray into ridge hunting, we learned that Meridiani has two distinct kind of polygonal ridges. There are regular polygonal ridges, which have straight connectors and enclose polygonal shapes (commonly found in northern Arabia Terra near Nili Fossae), and Meridiani ridges, which are often arcuate, enclosing circles or fractions of circles, and intersecting each other like tattered lace. While individual polygonal ridges are thin, Meridiani ridges can have wide, flat tops, or can appear splintered. There is a new tutorial to explain these two ridge types.

Your mission (should you choose to accept it) is to range around our new region of Meridiani, looking at images and classifying them into those that have regular polygonal ridges, those that have Meridiani ridges, and those which have neither (of which there are many!) I encourage you to use the “Done and Chat” button, hashtags, and collections to point out strange or mysterious things that you encounter on your way. There is a link on each image at the bottom (click the tiny “i” after clicking “Done and Talk”) that can take you to the source CTX image if you are curious about the area. Also don’t be afraid to zoom around on the Mars version of Google Earth (with the CTX global image layer on) and tell us what you find that way.

During this pandemic, many of us are cooped up in our homes with nowhere to go. Luckily, despite not being able to travel the Earth as we are used to, we are all free to fly over the vast empty deserts of planet Mars.

Whether you are a long-time Planet Four Ridge Hunter or you’re just joining us now, have fun exploring Mars and happy ridge-hunting!

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