New images of the mysterious Martian moon Deimos were captured on March 12 when the European Space Agency‘s (ESA) Hera mission activated its instruments for the first time beyond Earth.
The activity occurred on a flyby during the mission’s journey to collect close-up data from Dimorphos, the first asteroid ever deflected by human intervention, with NASA‘s 2022 DART mission. Hera launched in October 2024 aboard a SpaceX Falcon 9 rocket and carried two small CubeSats, armed with advanced sensors.
Hera Mission
Hera’s primary mission is to provide scientists with precise asteroid detection data to support developing a reliable and repeatable technique for future asteroid deflections. The probe will record data about the asteroid Dimorphos, which is in orbit around the larger Didymos asteroid. After the probe’s brief pit stop at Mars, it’s continuing its journey to Dimorphos, with the next trajectory adjustments scheduled for February and October of 2026.
“This has been the Hera team’s first exciting exploration experience, but not our last. In 21 months the spacecraft will reach our target asteroids, and start our crash site investigation of the only object in our Solar System to have had its orbit measurably altered by human action,” said ESA Hera mission manager Ian Carnelli.
Hera Observation Instruments Tested
The mission is equipped with advanced imaging and data collection capabilities to provide scientists with precise readings from the DART mission’s aftermath. The asteroid framing camera captures 1020×1020 pixel black-and-white visual images. The Hyperscout H hyperspectral imager can detect color invisible to the human eye, enabling scientists to identify a substance’s mineral makeup. Hera’s Thermal Infrared Imager provides temperature readings and information about surface properties like roughness and porosity.
“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 – demonstrating their excellent performance in the process!,” ESA’s Hera mission scientist Michael Kueppers said.
“Other Hera instruments we will utilise once we reach the Deimos and Dimorphos asteroids were not activated, either because they are not usable at such long range and rapid speed from a target – such as our PALT laser altimeter, possessing a maximum range of 20 km – or because they are hosted aboard Hera’s pair of CubeSats which will only be deployed at the asteroids,” Hera Principal Investigator Patrick Michel, Director of Research at CNRS / Observatoire de la Côte d’Azur added.
Deimos appears to cross Mars, captured by Hera Spacecraft (Image: ESA).
Close Mars Flight
While Mars isn’t the Hera mission’s primary object, the red planet is still essential. The ESA’s Flight Dynamics team planned the mission to take advantage of Mars’s gravity, flying Hera to within 5000 km of the planet and using it to alter the probe’s trajectory toward Dimorphos. Such a maneuver shaved months of travel time and precious fuel use off Hera’s journey.
robotic dog
While in position above Mars, moving around the plant at nine kilometers per second, Hera captured images of Deimos from only 1000 kilometers away. The tiny moon is just over twelve kilometers across, and its formation is still a mystery. Astronomers are uncertain if the moon was captured by Mars as an asteroid, or if the small ball of rock was ejected from the Martian surface during a massive impact event.
“Our Mission Analysis and Flight Dynamics team at ESOC in Germany did a great job of planning the gravity assist,” said ESA’s Hera Spacecraft Operations Manager Caglayan Guerbue. “This is especially true as they were asked to fine-tune the manoeuvre to take Hera close to Deimos—which created quite some extra work for them!”
Future Martian Missions
Hera’s Martian performance may be only a side task, but it holds tremendous potential for future Mars missions. The probe was even able to boost the existing Mars Express mission by conducting joint observations. Hera’s Deimos observations will provide essential data for planning The Japan Aerospace Exploration Agency (JAXA) led Martian Moons eXploration Mission (MMX). The MMX collaboration will receive additional support from many international space agencies, including ESA, NASA, France’s CNES, and Germany’s DLR. MMX will measure both Martian moons and conduct a return sample landing mission from the larger moon, Phobos.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.