A European spacecraft has taken photos of Mars’s smaller and more mysterious second moon during its flight past the planet en route to a pair of asteroids more than 110m miles (177m km) away.
The Hera probe activated a suite of instruments to capture images of the red planet and Deimos, a small and lumpy 8-mile-wide moon, which orbits Mars along with the 14-mile-wide Phobos.
The European Space Agency probe barrelled past Mars at more than 20,000mph and took shots of the lesser-seen far side of Deimos from a distance of 620 miles.
Michael Kueppers, Hera’s mission scientist, said: “These instruments have been tried out before, during Hera’s departure from Earth, but this is the first time that we have employed them on a small distant moon for which we still lack knowledge.”
Dust-covered Deimos is tidally locked with Mars, meaning it always shows the same face to the planet’s surface. The rock may be the remains of a giant impact with Mars or an asteroid that became captured by the planet’s gravitational pull.
Mars appears light blue in the shot taken by Hera’s near-infrared Hyperscout H imager during a gravity-assist flyby on Wednesday. The slingshot manoeuvre around the planet will propel the spacecraft out towards the pair of asteroids it is due to reach in December next year.
Deimos appears as a dark blob near the bottom of the image. Above it is the bright Terra Sabaea region near the Martian equator. To the bottom right of Terra Sabaea is the 280-mile-wide Huygens crater, and the similarly sized Schiaparelli crater is to the left. The large, smooth patch near the bottom right is part of the Hellas Basin, among the largest impact craters in the solar system.
Hera is bound for Dimorphos, a 150-metre-wide asteroid that orbits a larger, 780-metre-wide parent body called Didymos. In 2022, Dimorphos became the first asteroid to have its orbit altered by human action when Nasa’s Dart probe slammed into it. Hera will analyse the asteroid to understand whether the space rocks that threaten Earth in future could be deflected by such collisions.