Hera will also see Deimos – Kosmonautix.cz

Next March, the European probe Hera will come significantly closer to the planet Mars during its journey to the binary planet Didymos, where it will perform a gravitational maneuver. As part of it, it will reach just 6,000 kilometers above the surface of the Red Planet, which is closer than the distance at which the two moons of Mars orbit. The orbit and orientation of the probe in space will be adjusted so that it can test the functioning of its scientific instruments on Deimos, the smaller of the two Martian moons, from which it will be separated by only 1,000 kilometers. Hera will definitely not be bored during the flyby, because she should also observe Mars itself.

Details about the planned flyby were presented at a workshop of the scientific community around the Hera mission, which took place at the European Space Agency’s technology center, i.e. in the Dutch ESTEC. “The flyby of Mars is part of the planned maneuvers to bring the Hera probe to Didymos after a two-year flyby phase,” explains Michael Kueppers, a scientist from ESA involved in the Hera project, adding: “By passing through the gravitational field of Mars in its direction of motion, the probe will gain additional speed on its way forward. This close approach is not part of Hera’s main science mission, but we will still have several science instruments activated. The flyby gives us another chance to calibrate our instruments, and there’s also the potential for some scientific discoveries.“

His words are complemented by flight dynamics engineer Pablo Muñoz, who is part of the mission analysis team that calculates the trajectory: “It is indeed lucky that Mars happens to be in the right place at the right time to give Hera a helping hand. This allowed us to design a trajectory that would take advantage of Mars’ gravity to move Hera toward its rendezvous with Didymos, resulting in a significant savings in propellant for the entire mission. Part of the saved propellants will be used to accelerate the arrival to the binary planet by several months, thereby maximizing the scientific contribution of the mission and our knowledge in the field of planetary defense.“

Hera is scheduled to launch in October this year and its target will be the planet Didymos, whose dimensions ESA compares to a mountain. The marigold Dimorphos circles around this main body, whose dimensions ESA compares to the Great Pyramid of Giza for a change. It was this marigold that was hit by the American DART probe on September 26, 2022, and to continue the size comparisons, ESA likens this probe to a van. The impact at a mutual velocity of 6.1 km/s was the first practical test of a kinetic impactor, a method of planetary defense. The test was successful, as it was possible to change the trajectory of the target moon around the main planet.

The Hera probe will also investigate the consequences of the collision with the help of the two CubeSats Milani and Juventas.
Source: https://www.esa.int/

Now Hera is to conduct a close-up survey of Dimorphos to gather important missing information about the planet’s mass, chemical composition and structure. These data will make it possible to turn the previous DART mission into a much more complex experiment set in a wider context. After gaining new knowledge, the obtained data will be able to be used for a better understanding of the entire process, which could make this method a predictable and repeatable method of planetary defense. “Hera’s instruments were of course designed to observe Dimorphos, but they have the potential to obtain interesting data on Deimos, which also looks a bit like an asteroid,” notes Patrick Michel, research director at the Observatoire de la Côte d’Azur in Nice and also the principal investigator of the Hera mission.

Moon Deimos
Source: https://www.esa.int

Deimos (its name is derived from the Greek word for terror) orbits Mars at a distance of 23,460 kilometers and is the more distant of the two Martian moons. Its irregular body is 12.4 km in diameter and has a dark surface, reminiscent of C-type asteroids. After all, one theory is that both Phobos and Deimos are actually main belt asteroids that have been captured in the orbit of Mars. However, their surface characteristics have features in common with the planet they orbit, which in turn suggests their impact origin. “Deimos has never been observed before with the combination of instruments that Hera has, so we believe there will be some discoveries,” admits Patrick Michel, adding: “We will conduct observations in collaboration with the Hope probe from the United Arab Emirates, which launched in July 2020 and entered orbit around Mars in February 2021. We are also considering joint observations with Europe’s Mars Express and TGO probes. In addition, the data we collect will also be used in the planning of Japan’s MMX (Martian Moons eXploration) mission, which is scheduled to launch in 2026. MMX will explore both moons and should land a Franco-German rover on Deimos. In addition, it will take samples to transport to Earth.“

This is how Mars could be seen by the Spacecraft Monitoring Camera on the Hera probe. This engineering camera is located on the side that will be facing the asteroid during the science phase.
Source: https://www.esa.int

Hera will use a trio of her scientific instruments during her flyby of Mars (and thus Deimos). Its Asteroid Framing Camera will take pictures, while the HyperScout-H instrument will observe a wide spectrum of “colors” beyond the capabilities of the human eye. It thus collects mineralogical data in a total of 25 spectral bands in visible and near-infrared radiation. And finally, the Thermal Infrared Imager is (simply put) a heat imager. This instrument can distinguish surface features at local nighttime and also measure how the surface temperature changes over time, which will help refine the data on surface properties.

Translated from:
https://www.esa.int/

Image Sources:
https://www.esa.int/…/hera_s_mars_swingby/25470341-2-eng-GB/Hera_s_Mars_swingby.png
https://www.esa.int/…/hera_spacecraft/15357816-8-eng-GB/Hera_spacecraft.png
https://www.esa.int/…/moons_of_mars/26051357-1-eng-GB/Moons_of_Mars.jpg
https://www.esa.int/…/22247285-1-eng-GB/After_the_crash_comes_Hera.jpg
https://www.esa.int/…/26051404-1-eng-GB/Deimos_seen_in_high_resolution.jpg
https://www.esa.int/…/25470386-3-eng-GB/Mars_seen_from_Hera_s_top_asteroid_deck.png