The American space agency, NASA, created the first interactive map of the planet Mars, following in the footsteps of Google Earth software. Both scientists and the public can now explore the Red Planet in a model created by Caltech using data from NASA’s Mars Reconnaissance Orbiter.

The product created in the Bruce Murray Laboratory was developed over six years and tens of thousands of hours. The level of detail in the images is so high that more than 120 scientific papers have already cited and used this source of images. Of course, just like Google Earth, the mosaic is easy to use for anyone.

Images of the Mars Reconnaissance Orbiter

The interactive map of Mars is composed of 110,000 images captured by NASA ‘s Mars Reconnaissance Orbiter (MRO). Taken by the spacecraft’s black-and-white Context Camera (CTX), the images cover almost 25 square meters of surface for each individual pixel. This makes the Global CTX Mosaic of Mars software (here website), the largest high-resolution global image of Mars ever created. If printed, the 5.7 trillion pixel (5.7 terapixel) mosaic would be large enough to cover the entire Rose Bowl Stadium in Pasadena.

“I wanted something that was accessible to everyone” said Jay Dickson, the image processing scientist who led the project and manages the Murray Lab. “Schoolchildren can use it now. My mother, who just turned 78, can use it. The goal is to lower the barriers for people interested in exploring Mars”.

CTX is just one of three cameras on board the MRO. One of these cameras, the High-Resolution Imaging Science Experiment (HiRISE), provides color images of objects as large as a table. In contrast, CTX provides a wider view of the surface, helping scientists understand the correlation between features present on the Martian surface today. The latest camera, the Mars Color Imager (MARCI), produces a daily global map of the weather on Mars with much lower spatial resolution.

Six years of work

The MRO spacecraft arrived on Mars in 2006, and from the very beginning the CTX camera has documented almost everything on the Red Planet. The captured images have always been the starting point for scientists when they need to create a map. But the process is not simple at all. Creating a map requires downloading and sifting through a wide selection of images to find those with similar lighting conditions.

To create the new mosaic, Dickson developed an algorithm to match the images based on the features captured. Despite the computer assistance, he had to manually add and merge the remaining 13,000 images that the algorithm could not match. In some areas, the mosaic has gaps. These represent parts of Mars that were not captured by CTX when Dickson started working on this project, or areas obscured by clouds or dust.

Laura Kerber, a Mars scientist at JPL, provided feedback on the new mosaic as it took shape. “I’ve wanted something like this for a long time. It’s both a beautiful artistic product and useful for science”. In early tests, Kerber used the software to visit her favorite place on Mars, Medusae Fossae, a dusty region as large as Mongolia. Scientists are not sure how it formed, but Kerber has proposed that it could be a pile of volcanic ash. Now, with a simple click, users can zoom in and admire ancient river channels, now dried up, winding through the Martian landscape.

Following the Mars rovers

Users can “explore” very famous regions such as Gale Crater or Jezero Crater, areas still being explored by NASA’s Curiosity and Perseverance rovers, or visit Olympus Mons, the tallest volcano in the Solar System. One of the most interesting features of using the Global CTX Mosaic of Mars is to notice how irregular the Martian surface is. Impact craters are present all over the planet, allowing viewers to see how “scarred” Mars is.

“For 17 years, MRO has revealed Mars to us like never before” said Rich Zurek, the project scientist of the mission, from JPL. “This mosaic is a new and wonderful way to explore some of the images we have collected”. The software was funded as part of NASA’s Planetary Data Archiving, Restoration and Tools (PDART) program, which helps develop new ways to use existing NASA data.

Sofia Bianchi
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