See the First Detailed Close-Ups of Mars’ Moon Deimos

A United Arab Emirates spacecraft took a high-resolution look at the mysterious moon and uncovered new evidence about its origin

small grey moon in front of red planet
Mars and Deimos in a high-resolution composite image captured by the United Arab Emirates' Hope probe Emirates Mars Mission

A space probe operated by the United Arab Emirates has taken the most detailed photos yet of the Martian moon Deimos. Flying within 62 miles of the little moon, the probe, called Hope, got the closest to Deimos of any spacecraft since NASA’s Viking 2 mission in 1977, writes Deena Theresa for Interesting Engineering

The images, along with data collected from onboard instruments, challenge the longstanding theory that Mars’ two moons are captured asteroids—ultraviolet and infrared readings indicate Deimos is more similar in composition to Mars’ surface than to a carbon-rich space rock. This means it could have broken off from Mars itself or from its other moon, Phobos. These findings were presented at the European Geosciences Union’s general assembly on Monday. 

“How exactly [Mars’ moons] came to be in their current orbits is also an active area of study, and so any new information we can gain on the two moons, especially the more rarely observed Deimos, has the potential to unlock new understanding of Mars’ satellites,” Hessa Al Matroushi, the science lead of the Emirates Mars Mission, says in a statement.

Because Mars’ moons are tidally locked to Mars, they always show the planet the same face (like our moon and the Earth). Hope’s view of Deimos’ is the first clear look at its far side, according to the New York Times’ Jonathan O’Callaghan. 

Deimos is the smaller of Mars’ two moons, measuring just 9 by 7 by 6.8 miles, per NASA. The other, Phobos is a bit larger, at 17 by 14 by 11 miles. Phobos has been well-studied in the past because of its proximity to Mars. It’s located just 3,700 miles away from the Red Planet, giving it the closest orbit of any known moon in our solar system, and it completes about three trips around Mars per day. Deimos, on the other hand, averages about 14,500 miles away from Mars, and its orbit takes roughly 30 hours. 

Hope was launched in July 2020 and entered Martian orbit in February 2021. Its main goal has been to collect information on the planet’s atmosphere and weather patterns, which will help researchers understand more about ancient Mars’ capacity for supporting life.

While previous Martian spacecraft have orbited the planet closely to capture detailed observations of its surface, Hope has a higher and more elongated orbit, reaching about 25,000 miles above the planet at its highest point, writes Davide Castelvecchi for Nature News. This has allowed it to observe Deimos in more detail than previous probes.

Hope’s mission was intended to last just one Martian year (about two Earth years), but it was extended to continue studies of Deimos. The spacecraft will now pass across the small moon’s orbit multiple times.

“Phobos has got most of the attention up until now,” Al Matroushi tells Marcia Dunn of the Associated Press. “Now, it’s Deimos’ turn.”

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