Planetary defense mission Hera blasts off toward Mars

Hera will perform a swingby of Mars in March 2025 as a way of gathering extra momentum on its way to the Didymos binary asteroid system. The spacecraft will fly within the orbits of both Martian moons Deimos and Phobos, and perform science observations of the former body and the planet's surface, in synergy with the UAE's Hope orbiter and gathering preparatory data for JAXA-DLR's MMX Martian Moons eXploration mission due to be launched in 2026. ESA-Science Office

The European Space Agency (ESA)’s planetary defense mission, Hera, has completed the first major maneuver of its journey following its launch in October. The spacecraft has burned its thrusters to put it on a course toward Mars, which it should reach to perform a gravity assist flyby in 2025.

The mission is a follow-up to NASA’s DART mission, which deliberately crashed into an asteroid in 2022. DART was testing to see whether impacting a spacecraft into an asteroid could alter its trajectory, which it succeeded in doing. The idea is that if an asteroid should ever threaten Earth, space agencies could send a spacecraft to crash into it and knock it off course.

However, scientists want to know much more detail about what the exact effects of the DART impact on the asteroid were. They know that it reshaped the asteroid as well as changed its trajectory, but they want more information about what the asteroid is composed of and the exact effects of the impact. That’s where Hera comes in — it is traveling to that same asteroid, called Dimorphos, to observe it up close.

To reach the asteroid, Hera has performed its first maneuver consisting of two bursts from its thrusters on October 23 and November 6. “Deep-space maneuvers are often split into parts,” explained Sylvain Lodiot, Hera Spacecraft Operations Manager, in a statement. “The first, larger burn does most of the work. Then, after precisely measuring the spacecraft’s trajectory, we use the second, smaller burn to correct any inaccuracy and provide the rest of the required boost.”

The burns succeeded in changing the spacecraft’s trajectory and pointing it toward Mars, and it will now require just a small correction maneuver on November 21 to fine-tune its approach.

When Hera arrives at Mars, it will use the gravity of the planet to push it toward its target, Dimorphos, which is the smaller partner of the Didymos asteroid and where it will arrive in late 2026. While passing by Mars, Hera will perform science operations, including studying Mars’s small moon, Deimos, which it will pass within 185 miles of.

“We are very fortunate that Mars is in the right place at the right time to lend a hand to Hera,” said Pablo Muñoz of the ESA’s European Space Operations Centre. “This enabled us to design a trajectory that uses the gravity of Mars to accelerate Hera towards Didymos, offering substantial fuel savings to the mission and allowing Hera to arrive at the asteroids months earlier than would otherwise be possible.”