The mysterious Deimos was spotted while ESA’s planetary defense mission travels to its target asteroid.
This black and white image was taken by Hera’s Asteroid Framing Camera. This camera will be used to track Dimorphos through space and once it arrives at the destination it will image the impact crater left by NASA’s Double Asteroid Redirection Test. Credit: ESA
Hera, European Space Agency’s (ESA) flagship planetary defense mission that launched in October 2024, took images of Mars and Deimos, one of its two moons, yesterday. The mission’s flyby was used as a gravity assist to its final destination at the binary asteroid system Dimorphos and Didymos. The mission also used this journey past Mars as an opportunity to test some of its scientific equipment.
Deimos is the smaller and less photographed of Mars’ moons. This egg-shaped object, only measuring about 7.7 miles in diameter (12.4 kilometers), is tidally-locked with the Red Planet making it often difficult to get images of it from Earth.
The mission utilized three of its instruments as it got within 621 miles (1,000 km) of Deimos while hovering over the Hellas Basin region of Mars. Hera used its black and white Asteroid Framing Camera (above) which is used for both navigation and scientific purposes. This camera is used to indicate what characteristics appear in visible light. In the image, Deimos appears dark compared to the Red Planet. That is because its surface is composed of carbonaceous regolith that does not reflect light easily.
During the trek, Hera also used its Hyperscout H hyperspectral imager to capture the surface of Mars and Deimos in 25 visible and near-infrared spectral bands. This imager gives a better sense of an object’s mineral makeup.
With its Thermal Infrared Imager, Hera snapped a picture showing the significantly warmer surface of Deimos versus Mars below it. This moon lacks an atmosphere and is pointed toward the Sun in the image. Hera’s Thermal Imager also picks up on qualities such as the surface’s temperature as well as particle size, porosity, and roughness.
Hera has a total of 12 payloads aboard, as well as two cubesats that it won’t release until after it reaches Dimorphos and Didymos in December 2026. When it arrives at the asteroids, it will study the impacts from the NASA’s Double Asteroid Redirection Test collision conducted on Dimorphos in 2022.
This flyby imaging was not only supportive of Hera’s mission, but it will also assist other future endeavors. This includes the Martian Moons eXploration mission (MMX) led by Japan Aerospace Exploration Agency along with several other agencies including NASA and ESA. This mission will collect data from Deimos as well as Mars’ other moon, Phobos, where it will eventually land and collect samples to bring back to Earth. The mission is anticipated for a 2026 launch.
