Deimos vs. Phobos

Attribute	Deimos	Phobos
Diameter	12.4 km	22.4 km
Distance from Mars	23,460 km	9,378 km
Orbital Period	30.3 hours	7.7 hours
Surface Gravity	0.003 m/s²	0.0057 m/s²

Introduction

Deimos and Phobos are the two moons of Mars, and they are both small and irregularly shaped. Despite their similarities, they have distinct characteristics that set them apart from each other. In this article, we will compare the attributes of Deimos and Phobos to highlight their differences and similarities.

Size and Shape

Deimos is the smaller of the two moons, with a mean radius of about 6.2 kilometers. It has an irregular shape and is heavily cratered, giving it a lumpy appearance. Phobos, on the other hand, is larger with a mean radius of about 11.1 kilometers. It also has an irregular shape but is smoother in appearance compared to Deimos.

Surface Features

Deimos has a relatively smooth surface with numerous impact craters, the largest of which is named "Voltaire." The surface of Deimos is also covered in a layer of fine dust and regolith. Phobos, on the other hand, has a more rugged surface with a prominent feature known as the "Stickney crater," which is the largest crater on the moon. Phobos' surface is also covered in regolith, but it has more grooves and linear features compared to Deimos.

Orbital Characteristics

Deimos orbits Mars at a distance of about 23,460 kilometers and takes approximately 30.3 hours to complete one orbit. Its orbit is nearly circular and is located outside of Mars' synchronous orbit radius. Phobos, on the other hand, orbits much closer to Mars at a distance of about 9,378 kilometers and takes only 7.7 hours to complete one orbit. Phobos' orbit is significantly more elliptical compared to Deimos.

Origin and Composition

Deimos and Phobos are believed to be captured asteroids that were pulled into orbit around Mars. Deimos is thought to be composed of a mixture of rock and ice, similar to C-type asteroids. Phobos, on the other hand, is believed to be composed primarily of carbonaceous chondrite material, which is a type of stony meteorite. This difference in composition suggests that Deimos and Phobos may have originated from different regions of the asteroid belt.

Gravity and Surface Features

Due to its smaller size and mass, Deimos has a weaker gravitational pull compared to Phobos. This results in a surface gravity on Deimos that is only about 0.003 m/s^2, making it difficult for objects to stay on the surface. Phobos, on the other hand, has a slightly stronger gravitational pull with a surface gravity of about 0.0057 m/s^2. This difference in gravity has implications for the surface features of the two moons, with Phobos having more prominent cliffs and grooves compared to Deimos.

Potential for Future Exploration

Both Deimos and Phobos have been proposed as potential targets for future exploration missions to Mars. Due to their proximity to the planet, they could serve as important stepping stones for human missions to Mars. Deimos, with its smoother surface and lower gravity, may be easier to land on and explore. Phobos, with its more rugged surface and higher gravity, presents more challenges but also offers unique scientific opportunities. Future missions to these moons could provide valuable insights into the history and geology of Mars.