Phobos is one of the two Mars moon. The biggest. But it’s still a very small moon compared to us. Its maximum diameter does not exceed 27 kilometers. Its surface is marked by large craters. Its diameter is about nine kilometers. On the surface of Phobos there are also other craters, and strange scratches. And that’s not to mention the fact that this tiny moon seems to be inexorably closing in on Mars. So much so that it could crumble into rings in a few tens of millions of years. Many features that have long intrigued astronomers.
And they finally managed to see it up close thanks to the Mars Express mission of the European Space Agency (ESA). Launched in 2003 to study the internal structure of Mars, it carries on board an instrument called Marsis – per Mars Advanced Radar for subsurface and ionospheric surveys. The idea: for red planet low-frequency radio waves and analyze the nature of the waves sent back from the ground, but also from deeper layers.
After a major software upgrade to the Marsis instrument, astronomers were able to gather important data on the first Mars Express launch near Phobos. Less than 85 kilometers away. Knowing that the line separating our atmosphere from interplanetary space is at an altitude of about 100 kilometers, that is… All because “Getting up close allowed us to study its structure in more detail and identify important features that we would never have been able to see from afar. In the future, we are confident that we can use Marsis within 40km – this instrument was originally designed to study Mars at a distance of 250 kilometers. The orbit of Mars Express has been adjusted to get us as close to Phobos as possible in just a few flybys between 2023 and 2025, which will give us a chance to try it out.”defines Andrea Cicchetti, researcher, in a ESA press release.
Asteroids or rocks torn from Mars?
What the researchers hope is that Mars Express data could shed light on the origin of Phobos. Why astronomers are still in doubt. Perhaps the moons of MarsKuno asteroid captured by the Red Planet. This is what their appearance and composition indicate. But not their eye sockets. So they too could, like our Moon, be chunks of rock ripped off Mars by an impact.
The data collected on September 23 is very rich and the analysis is still in its infancy. However, researchers have identified in “radargram”, signs of a more or less harmless surface structure. But even the faintest hint of what appear to be much more interesting underground features. This layered structure could indicate that Phobos is indeed an ancient asteroid. But who can point to a constitution “floating pile of garbage”.
The following close-up of Mars Express in the sky above Phobos should reveal more. And mission Exploration of the moon of Mars (MMX), in collaboration with the Japanese Space Agency, which will soon land on Phobos – not before 2024 – to samples were collected should help clarify a bit more. These samples, brought back to Earth in 2029, should finally solve the mystery of the origin of the moons of Mars.
