Phobos and Deimos the Moons of Mars Phobos Deimos Asteroids Moons

Mars has two small moons, Phobos and Deimos, these two moons are named with Greek words for “fear” and “terror” respectively. These two moons are both thought to be captured asteroids and were discovered by Asaph Hall, a famous American astronomer, while he was working at the US Naval Observatory in Washington.

Phobos and Deimos are both tidally locked to Mars; which means that they always present the same faces towards the planet. But the time it takes the moons to orbit Mars is different, Phobos is the faster and orbits in just around 7hours and 40 minutes, opposed to Deimos which needs 30.5 hours for a complete orbit.

Phobos is the larger of the two moons; it is shaped irregularly with a diameter of 22kilometres and has a very low gravity. To compare with the Earth it is just 1/1000th and this would make it extremely difficult to attempt walking on Phobos. This extremely low gravity makes it possible for a person to jump out and orbit around Phobos itself.

Phobos is also known for the noticeably Stickney crater. Phobos was once hit by an asteroid and the impact changed the structure of the moon significantly. But Phobos is slowly spinning inwards while it orbits around Mars, it is calculated that Phobos gets 1.8 metres closer to Mars every century. Eventually this will cause Phobos to either crash into Mars or form a ring around the planet.

Deimos is one of the smallest moons in our solar system and has a diameter of just 12kilometres, making it almost half the size of Phobos. Like its big brother is Deimos also irregular in its shape, and to do its tiny size, it just appears as a bright star if it was to be viewed from Mars.

Deimos has just like Phobos a very low gravity and attempting to walk on this moon would require a type of restraint to prevent ending up orbiting around the moon itself.

Scientifically Interesting
Scientists find the two moons very interesting cases and would like the opportunity to explore them. The moons have like Mars frozen water present and could be of potential interest in the future. Both moons is made from a material called carbonaceous chondrites, which are also present in the Asteroid belt, making the theory that the two moons are captured Asteroids more likely.

Scientists hope, that exploring the two moons can give a better insight in similar sized Asteroids in our Solar System, as well as the potentials of using Phobos as a base for astronauts to observe Mars.