Zurich – According to simulations by Zurich researchers, Mars used to be orbited by only one satellite. A larger chunk hit this celestial body, which then burst – into the small Martian moons Deimos and Phobos. Due to their shape and size, these were previously thought to be two captured asteroids. But they orbit their mother planet in a circle in its equatorial plane, which speaks against this theory.
The researchers at ETH and the University of Zurich led by the geophysics doctoral student Amirhossein Bagheri have now drawn a different story of these two satellites based on computer simulations: Deimos and Phobos are the remains of a dismembered primordial moon, they report in the specialist magazine Nature Astronomery. In addition, Deimos is currently moving very slowly away from the red planet, while Phobos will fall on Mars in about 39 million years or will be torn apart by gravitational forces when it approaches.
Tiny compared to our moon
The Martian moons Phobos and Deimos, discovered in 1877, look like two potatoes and have a diameter of 22 and twelve kilometers respectively – compared to the terrestrial satellite, they are tiny. With their simulations, the researchers found that the orbits of the Martian moons, which are made of porous material, must have crossed in the past. “That means that the moons were very likely in the same place and must therefore have the same origin,” said ETH geophysicist Amir Khan in a broadcast from the university.
The exact time depends on the physical properties of Phobos and Deimos,” Bagheri was quoted as saying. In 2025, a Japanese probe is to collect rock samples from Phobos, which the researchers hope to refine their calculations. (WHAT / SDA)