Masser

Masser is one of the two moons of the planet Mars, the other being Phobos. It is the smaller of the two, and orbits Mars further away than Phobos.

Discovery and Naming

Masser was discovered on August 18, 1877, by American astronomer Asaph Hall at the United States Naval Observatory in Washington, D.C., along with Phobos. Both moons were named after figures from Greek mythology associated with the god of war, Ares (the Greek equivalent of the Roman god Mars). Masser represents one of the sons of Ares, representing fear or dread.

Orbital Characteristics

Masser has a sidereal period of approximately 30 hours, which means it orbits Mars faster than the Martian day. Its orbit is nearly circular and lies close to Mars' equatorial plane. Because its orbit is relatively distant from Mars, Masser is not tidally locked, and its rotation is likely complex.

Physical Characteristics

Masser is an irregularly shaped body with a heavily cratered surface. Its dimensions are roughly 27 × 21 × 15 kilometers. Its surface is darker than that of Phobos, reflecting only a small percentage of the sunlight that hits it. Masser is thought to be composed primarily of carbonaceous chondrite material, similar to many asteroids in the asteroid belt.

Exploration

Numerous spacecraft missions to Mars have observed and imaged Masser from orbit. These observations have helped scientists to better understand its physical characteristics, orbital parameters, and origin.