Preparing for Hera’s asteroid phase

Short-term activities are supplemented by medium- and longer-term planning. This includes liaising with the scientists to schedule observations within the flight plan and preparing all other aspects of the asteroid phase – the six-month period when Hera will perform its close-up asteroid survey.

Sylvain Lodiot, heading ESA’s Outer Solar System and Planetary Defence Operations, notes: “The frequency of passes will go up to one per day or even more during key events such as when we performed our two deep space manoeuvres, our March 2025 flyby of Mars, and our recent software update, then later during the asteroid phase to come.

“But that’s not to say the rest of the time is quiet! In fact, this has been among the most demanding cruise phases of any ESA mission. This is because it was absolutely essential for Hera to launch on schedule: a lift-off off two years later – the next time Mars would be lined up for the flyby that contributed an essential velocity shift for the mission – would have led to a much longer overall travel time. With this in mind, plenty of tasks had to be left until after launch to be taken care of.”

Safety first

This included the mission’s flight software, which initially lacked full ‘fault detection, isolation and recovery’ (FDIR) capability. What this meant was that the mission might not be able to recover autonomously from any onboard error.