The European Space Agency's (ESA) HERA spacecraft captured rare images of Mars' mysterious moon, Deimos, as it passed by the planet on its way to study a historic asteroid collision. The HERA mission aims to determine the impact of NASA's spacecraft intentionally colliding with an asteroid in 2022.
However, HERA won't reach the Dimorphos asteroid targeted by NASA's DART mission until the end of 2026.
During its long journey, HERA passed close to Mars on Wednesday, using the planet's gravity to assist in its maneuver. ESA mission analyst Pablo Munoz explained that this maneuver helped the spacecraft gain speed, change direction, and save fuel.
As HERA passed approximately 5,600 kilometers from Mars' surface, it reached a speed of 33,480 km/h and tested its scientific equipment. The spacecraft took around 600 images, including rare photos and data of Deimos.
Deimos is the smaller of Mars' two moons and is less well-known than Phobos. The moon, about 12.5 kilometers in diameter, has sparked debates among scientists about its origin.
Some believe Deimos and Phobos are asteroids captured by Mars' gravity, while others suggest these moons could be debris ejected from Mars' surface due to a massive collision.
HERA's next target is the Dimorphos asteroid. NASA's DART mission, in 2022, collided with Dimorphos, shortening its orbit around its larger sibling, Didymos, by 33 minutes.
Although Dimorphos does not pose a threat to Earth, HERA's work will help determine whether similar methods could be effective if Earth faces a real asteroid threat.
The European Space Agency is developing observation systems to monitor new threats as part of its planetary defense efforts.
Earlier this year, the possibility of a city-sized asteroid impacting Earth in 2032 was estimated to be above 3%. However, further observations have nearly reduced that probability to zero.
ESA's planetary defense office official Richard Moissl noted that with the advancement of sky observation technologies, such asteroids will be discovered more frequently.
The agency is also planning a new defense mission for the 350-meter-wide Apophis asteroid, which will come within 32,000 kilometers of Earth in 2029. ESA's Ramses mission, if launched in 2028, will reach Apophis two months before its closest pass to Earth.
