Discovery and Exploration
The moons of Mars have a fascinating history and continue to intrigue scientists with ongoing and planned exploration missions.
These rocky satellites hold clues to the Martian past and may pave the way for future exploration.
Historical Discoveries
In 1877, American astronomer Asaph Hall discovered Mars’ two moons, which he named Phobos (Mars I) and Deimos (Mars II).
These discoveries at the United States Naval Observatory marked a significant milestone in our understanding of the Martian system.
Hall’s work shifted our perspective on Mars, revealing that it was accompanied by its own small moons, much like Earth’s singular moon orbits our planet.
Ongoing Missions and Future Plans
In recent years, NASA has sent rovers like Curiosity to Mars to advance the exploration of the Martian surface, but attention is also turning back to its moons.
The Japan Aerospace Exploration Agency (JAXA) has demonstrated a keen interest in these celestial bodies with its Martian Moons Exploration (MMX) mission, aiming to study Phobos and Deimos and potentially return samples to Earth.
This mission follows the success of Hayabusa and Hayabusa2, which set the stage for asteroid sample return and have contributed to the strategy for the Martian moon exploration.
JAXA’s MMX mission could reveal much about Mars’ formation and history, and perhaps even help prepare for future human exploration by unraveling the mysteries of its orbital companions.
Physical Characteristics
Mars’ moons, Phobos and Deimos, are intriguing celestial bodies that exhibit unique characteristics largely differentiated by their physical features and dynamic processes.
Orbital and Rotational Dynamics
Phobos and Deimos follow nearly circular orbits around Mars with the former being the larger, yet closer to the Martian surface.
Both moons have synchronous rotation, meaning they always show the same face to Mars as they orbit.
Deimos takes about 30.3 hours to complete its orbit, which is significantly longer than Phobos, which orbits Mars every 7.6 hours.
Geological Features
The geology of the Martian moons is marked by a high density of craters, evidence of their history of impact events.
Phobos’s most prominent feature is Stickney, a massive crater that nearly spans half the moon’s diameter, suggesting a violent impact history.
Composition and Surface Analysis
Phobos and Deimos are believed to be made of carbonaceous chondrite, similar to many asteroids, suggesting a potential captured origin.
The surface of Phobos is covered with a layer of regolith, a powdery substance generated from debris produced by impacts over eons. Material on Phobos and Deimos includes these dusty regoliths and may harbor ice beneath their surfaces, though solid confirmation awaits future missions.
The exploration of Martian moons is expected to provide vital insights into their composition and the physical and optical properties of their surfaces.
Relationship with Mars
Mars, often referred to as the Red Planet and known to the Romans as Ares, the god of war, boasts two small moons that profoundly influence and are influenced by their larger parent planet.
As Mars spins in our solar system, these satellites remain cosmic enigmas, each with a story interwoven with the history of the fourth planet from the Sun.
Gravitational Impact on Mars
The gravitational relationship between Mars and its moons is a classic celestial dance.
The Martian moons, Phobos and Deimos, follow almost circular orbits around Mars.
Interestingly, Phobos, the closer and larger of the two, has a profound impact due to its gravity, which causes tides in the Martian crust similar to how our Moon influences Earth.
Over the millennia, these tidal forces can affect the planet’s rotation and the moon’s orbit, gradually altering their relationship.
Influence of Mars on Its Moons
The influence Mars has on its moons is just as significant.
For example, the Martian atmosphere casts a shadow on the surfaces of Phobos and Deimos, affecting their temperature and, subsequently, their surface features.
The Red Planet’s gravity helped these moons coalesce from the – possibly martian or asteroidal – debris left over from a massive impact and affects their geologic history.
The two moons may also offer clues about the presence or absence of rings around Mars in the past.
As meteorites crash into the Martian surface, they can eject material that may have been caught by the moons’ gravities, adding to the moons’ layers over billions of years.