(ORDO NEWS) — In 1877, American astronomer Asaph Hall discovered two objects orbiting Mars. They were Deimos and Phobos.
Although Phobos has been observed hundreds of times since then, its origin is still a mystery.
However, new observations by astronomers have added even more questions as Mars Express has discovered previously unknown structures inside Phobos.
The European Space Agency (ESA) recently upgraded the MARSIS instrument on Mars Express to allow it to be used at much closer ranges.
The spacecraft during its last flight approached the surface of Phobos at a distance of 83 kilometers.
MARSIS sends low frequency radio waves towards Mars or Phobos.
Although most of these waves are reflected from the surface of the body, some pass through and are reflected at the boundaries between layers of different materials below the surface.
By studying the reflected signals, the scientists were able to map the structure below the surface and study the thickness and composition of the material.
During the flyby, the spacecraft was transmitting radio signals to Phobos, and the echoes showed that they were bouncing off something unknown and returning back.
The continuous bright line shows an echo from the Moon’s surface, and the reflections below are either “disorder” caused by features on the Moon’s surface or, more interestingly, signs of some kind of structural features below the surface.
“The question of whether the two small moons of Mars are captured asteroids or made from material torn from Mars during the collision remains open.
Their appearance suggests they were asteroids, but the way they orbit Mars may suggest otherwise,” said SA Mars Express scientist Colin Wilson.
A team of astronomers is in the early stages of exploring Phobos with Mars Express, although we have previously seen signs of unknown structures below the surface of the Moon.
Perhaps MARSIS will help scientists solve the mystery of the origin of Phobos.
Earlier, scientists from the SETI Institute hypothesized that Phobos was once a ring-shaped pile of rocks in orbit around Mars. Later, they formed a solid cosmic object, which after 100 million years may again disintegrate.
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