Hera’s bold Mars flyby: a giant leap forward

Here we are again, at Frankfurt Airport, after another successful milestone for Hera. On March 12, around midday, Hera performed a flyby of Mars, meaning that she "stole" some of its energy to receive a push toward her final target, Didymos. This kind of technique is quite common in space travel, as it drastically reduces the amount of propellant needed onboard. In fact, Hera received an additional push of almost 1 km/s, which would be equivalent to her entire fuel reserve!

Of course, that was not all. Since the GNC is functioning well, and the autonomous navigation using centroiding technologies was already successfully executed the day after LEOP, the idea was to go further and test a fully experimental technique called feature tracking, using Mars as the target. GMV implemented that algorithm with low priority, as Hera's schedule was very tight and prioritization was crucial. The plan was to use it only after the mission's main objective had been achieved. However, we dared… and we succeeded!

The major concern in the ESOC control room in Darmstadt, Germany, was that a safe mode could be triggered due to this test, which would have reduced the amount of scientific data from the Mars flyby. However, testing this technology would provide additional flexibility for close proximity navigation when Hera approaches the asteroids. It was a trade-off, as always, but we need to trust our system, knowing that we will have to face an unknown environment (such as a double asteroid system) with very little time to adjust or adapt to the unexpected. So, the choice was made: "green light" for feature tracking on Mars.