A space probe flew past Mars’ moon to take a peek inside : ScienceAlert
The long-standing mystery of the origin of the Martian moons could be one step closer to being solved.
A space probe has come within tens of kilometers of the larger of the two sibling satellites to capture data on what lies beneath its cratered surface.
“Do you marsWhether the two small moons are captured asteroids or made of material torn from Mars during the collision is an open question.” says astronomer Colin Wilson European Space Agency (ESA). “Their appearance suggests they were asteroids, but the way they orbit Mars suggests otherwise.”
Phobos, named after the ancient Greek deity of fear and panic, is larger than two moons with a diameter of 22.2 kilometers (13.8 miles) and orbits Mars at an average distance from the surface of about 6,000 kilometers.
Deimos, after the Greek god of fear and terror, is only 12.6 kilometers (7.8 miles) wide and has a much greater average orbital distance of about 20,000 kilometers from Mars.
Both are quite unusual objects, quite different from our own companion in many ways. There are also some interesting differences between them.
As Deimos drifts away and may one day escape Mars entirely, Phobos moves toward Mars in a decaying orbit that shrinks by 1.8 centimeters (0.7 inches) each year, a journey that could see pull apart to form a ring in the next 100 million years or so.
It is also unclear where they came from. More compelling evidence suggests that our Moon separated from Earth in a giant collisionbut Mars and its moons, millions of kilometers away, are not so easy to study.
Compositionally, Phobos and Deimos they look quite similar, suggesting that they may have come from the same source; and that composition is similar to the group of asteroids. But they also have similarly neat orbits that are nearly circular and stick fairly close to the Martian equator, a feature not typical of captured asteroids.
One way of looking for answers is to look under the hood, so to speak – to find out what lies beneath the surface of the moon. ESA sent them Mars Express the Phobos flyby orbiter, flying within 83 kilometers (about 51 miles) of the potato-like satellite. For context, the Karman line that separates Earth’s atmosphere from interplanetary space lies at about 100 kilometers above sea level. The flight is only 83 kilometers long close.
“We didn’t know if this was possible,” says Mars Express flight controller Simon Wood of ESA. “The team tested several different variations of the software, and the final, successful setup was uploaded to the spacecraft just hours before the flyby.”
The flight itself took place at the end of September. The goal: to use an instrument called the Mars Advanced Radar for Sounding the Subsurface and Ionosphere (MARSIS) to probe beneath the surface of Phobos.
This is a radar instrument that sends low frequency radio waves to Mars; the way these waves bounce off different materials below the surface allows scientists to understand what might be there.
This is how scientists could have guessed that it might exist lakes of liquid water (or clay depositsor volcanic rock depositsor layers of rock and ice) buried beneath Mars’ south polar ice cap. Now the instrument is preparing to demystify the internal structure of Phobos.
“We are still in the early stages of our analysis,” says astronomer Andrea Cicchetti of the National Institute of Astrophysics in Italy, which manages MARSIS. “But we’ve already seen possible signs of previously unknown features down the line months surface. We are excited to see the role MARSIS could play in finally solving the mystery surrounding Phobos’ origin.”
Over the next few years, Mars Express will fly even closer to the bumpy little moon. From 2023 to 2025, the probe will fly, the team hopes, as close as 40 kilometers to the surface of Phobos. This will provide opportunities to gather even more data about its internal structure.
In addition, space agencies around the world are collaborating on it Exploring the Moons of Mars mission. This ambitious project aims to send a probe to both Phobos and Deimos and study them in detail – and collect a sample from Phobos and bring it back to Earth for detailed analysis.
Maybe then we’ll finally have an answer about the birthplace of the two tiny Martian freaks.
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