Mars Reconnaissance Orbiter sends home photos from the Red Planet

Every two years, the planets are positioned such that the travel time from Earth to Mars is at its shortest. 2020 was just such a year and it saw space missions including UAE’s Hope Probe take off to the Red Planet. But there is a predecessor to the Hope Probe. NASA’s Mars Reconnaissance Orbiter left 15 years ago, and now is providing photos and cues to what’s on the mysterious planet. Here’s a look at a few of the images the orbiter's top-of-the-class cameras threw up.

Dust storms are routine on Mars. Most are limited to small regions and are not as dramatic as what's portrayed in movies. But once or twice a decade, a series of regional storms will create a domino effect, lifting enough dust for winds to cover the surface in what's called a "planet-encircling dust event." This one, captured by Mars Color Imager (MARCI) in the summer of 2018, darkened the region above the Opportunity rover, depriving its solar panels of sunlight and ultimately leading to the end of the mission.

As the camera High-Resolution Imaging Science Experiment (HiRISE) pans over large swaths of Mars' surface, it occasionally discovers surprises like this towering dust devil, which was captured from 185 miles (297 kilometers) above the ground. The length of this whirlwind's shadow indicates that it was more than half a mile (800 meters) high – about the size of the United Arab Emirate's Burj Khalifa, the tallest building on Earth.

HiRISE has captured avalanches in action. As seasonal ice vaporized in the spring, these 1,640-foot-tall (500-meter-tall) cliffs at Mars' north pole began to crumble. Such cliffs reveal the deep time scales on the planet, exposing the many layers of ice and dust that have settled during different eras. Like the rings of a tree, each layer has a story to tell scientists about how the environment was changing.

Mars has a thin atmosphere – just 1% as dense as Earth's. As a result, there's less of a protective barrier to burn up space debris. That means larger meteors make it through the Red Planet's atmosphere than Earth's. CTX has detected over 800 new impact craters during MRO's mission.

Earth to Mars

MRO hasn't only looked at Mars. This composite, made from four sets of HiRISE images of Earth and our Moon, was actually the second time that HiRISE had captured our home planet.

Named for the Greek god of fear, Phobos is one of Mars' two moons (Deimos, named for the god of terror, is the other), and it's only about 13 miles (21 kilometers) across. Stickney Crater, the indentation on the moon's lower right, is about 5.6 miles (9 kilometers) wide in this HiRISE image. Despite its small size, Phobos is of great interest to scientists: Is it a captured asteroid, or a chunk of Mars that broke off after a massive impact? A Japanese mission is scheduled to launch to Phobos in the near future, and the moon has been proposed as a staging ground for astronauts before they go to Mars.

Based on an image from CTX, this map shows the complete traverse of the Opportunity rover after exploring the planet for more than 15 years. Both HiRISE and CTX are used by scientists to make maps of landing sites for future human and robotic missions as well as to chart the progress of rovers on the ground.