The mysterious moons of Mars

Mars is a true Wonderland world that has sung its tantalizing siren song for centuries for those seeking to solve its many mysteries. In fact, the two moons of Mars, called Phobos Y Deimos, present some fascinating mysteries of their own. Where do the two moons of Mars come from? For a long time, their strange irregular shapes have suggested that they were both born asteroids that escaped from the Handheld Asteroid Belt between Mars and Jupiter, only to be caught in the Red Planet’s gravitational embrace when they wandered too close to what would become their foster parent planet. However, in April 2018, planetary scientists from the Southwest Research Institute (SwRI) in San Antonio, Texas, he presented an alternative scenario to explain the origin of these two small potato-shaped moons. The new theory proposes that Phobos Y Deimos were actually born as a result of an ancient shock when a little dwarf protoplanet exploded on primordial Mars. The article describing this new model is published in the April 16, 2018 issue of the magazine Scientific advances.

The primordial solar system has often been likened to a “cosmic shooting gallery” where objects, large and small, continually collide with each other, wreaking havoc. The ancient giant collision between young Mars and an unfortunate protoplanet it would have been almost identical to the one generally believed to have been responsible for the formation of Earth’s great Moon. According to this model, Earth’s Moon was born when a damned size of Mars protoplanet called Theia crashed into our planet still in formation.

Astronomers have been debating the origin of the mysterious duo of Martian moons for decades. The perplexing puzzle, which has been difficult to solve, is whether the moons are really captured asteroids. gold they were born instead from a disk of debris revolving around primordial Mars. This surrounding debris disk would have originated as a result of the proposed giant impact. This giant impact model that explains the origin of Phobos Y Deimos has been considered the most promising explanation. Unfortunately, earlier models of this process were hampered by low numerical resolution, as well as oversimplified modeling technology.

In the case of the giant impact model between the primordial Earth and the tragedy that was Theia, the violent impact threw debris into the sky above our planet. Eventually, the debris coalesced to create Earth’s enchanting lunar companion.

“Ours is the first self-consistent model to identify the type of impact needed to lead to the formation of the two small moons of Mars,” noted study lead author Dr. Robin Canup on April 16, 2018. SwRI press release. Dr. Canup is Associate Vice President of the SwRI Division of Engineering and Space Sciences, as well as a leading scientist using large-scale hydrodynamic simulations to model planetary-scale collisions, including the favorite Earth-Moon giant impact formation model.

A whole pair

Since its discovery in 1877 by the American astronomer Asaph Hall (1829-1907), Phobos Y Deimos they have bewitched and baffled astronomers seeking the elusive answer to the question of how Mars managed to acquire its duo of strangely shaped little moons. Phobos has an orbit that brings it closer to Mars than its sister moon, with a semi-major axis of 5,827 miles, as opposed to Deimos’ 14,580 miles.

When a moon is in orbit around its parent planet, all is well for both the planet and its moon.as long as the gravity that holds the moon in one piece overcomes the relentless and powerful pull of its planet. The trouble begins if the unfortunate moon gets too close to the gravitational clutches of its destructive parent planet. This is because the planet’s tidal forces begin to exceed the gravitational bond that holds the unfortunate moon together.is it means the moon will crumble. Earth’s relatively large Moon is very fortunate because the boundary, called Roche limit– it is a little less than 10,000 kilometers, and it is a safe and protected 385,000 kilometers from our planet.

Unfortunately, other moons may not be so lucky. This fortunate situation for Earth and its lunar companion is not the case for Martian moons. Phobos It is the largest moon of the duo, at about 22 kilometers in diameter, and is currently slowly heading toward Mars. Phobos it’s a doomed little lunar world, because it will get closer to the martian Roche limit in about 20 million years. When it does, Phobos it will separate, forming a mess of debris that will create a spectacular ring around the Red Planet. Unlike, Deimos– the youngest of the duo – will remain without his moon companion. Deimos orbits its parent planet at a greater and safer distance. This last surviving Martian moon will become a lonely object that remains in the Martian sky.

If an observer stood on the Martian surface near its equator, Phobos it would appear to be about a third the size of Earth’s full Moon. But nevertheless, Phobos it would look considerably smaller if the observer stood further from the Martian equator, and would be completely invisible if the observer looked up at the Martian sky while standing on one of its polar caps. Deimos it looks more like an especially bright star or planet when viewed by an observer on Earth. There are no total solar eclipses on Mars. This is because the moons are too small to completely block the sun. In dramatic contrast, the total lunar eclipses of Phobos they happen almost every night.

The movements of the Martian moons would appear very different from those of Earth’s own Moon. The demon of speed Phobos It rises in the west, sets in the east, and then rises again only eleven hours later. Secondly, Deimos– being just out of synchronous orbit – it rises as expected in the east. However, Deimos performs this feat very slowly. Despite its 30-hour orbit around its parent planet, it takes 2.7 days to Deimos to get in the west as it lazily falls behind the rotation of Mars.

Both Martian moons are tidally locked, always showing the same face toward Mars. Several string craters have been observed marking the Martian surface, and they lean more from the equator the older they are. This suggests that there may once have been many small moons that perished in the manner currently predicted for the damned. Phobos …and that the Martian crust as a whole moved between these events. Unlike, Deimos it is far enough away from its parent planet that its orbit is slowly propelled, as is also the case with Earth’s own Moon. When Earth’s Moon was born, it was much closer to our planet. The primordial Moon was a considerably larger object in Earth’s ancient sky than it is now. With the passage of time, the Moon from the Earth grew farther and farther away; seeming to get smaller and smaller in the sky as a result.

The birthplace of the Martian moons is a hot topic of debate. Both little moons have a lot in common with type C carbonaceous asteroids, with albedo, density and spectra very similar to those of VS- gold Type D asteroids. Due to this similarity, one theory suggests that both moons can be captured. Asteroids of the main belt. However, both Phobos Y Deimos they have circular orbits that are located almost exactly in the equatorial plane of Mars. For this reason, a capture origin requires a mechanism to circularize the initially highly eccentric orbits and adjust their inclinations in the equatorial plane. This would likely have resulted from a combination of atmospheric resistance and tidal forces, although it is not clear that there is enough time available for this to happen in the case of Deimos. Circular orbits are an indication that the orbiting body was born where it is, while eccentric orbits indicate the opposite. Another problem with the capture theory is that the capture itself requires energy dissipation. The atmosphere of Mars today is too thin to capture a Phobos-size object by atmospheric braking. However, a capture may have occurred if the original body was actually a binary asteroid that separated as a result of tidal forces.

An explosion in the Martian past

The new model proposes a much lower impact protoplanet than those considered in previous studies. The catastrophic impact believed to have created Earth’s Moon occurred approximately 4.5 billion years ago, a time when our 4.6 billion-year-old Solar System was very young. The diameter of Earth is about 9,000 miles, while the diameter of Mars is just over 4,200 miles. Earth’s Moon is just over 2,100 miles in diameter, about a quarter the size of Earth.

Phobos Y Deimos formed within the same time period. Both tiny moons hug their parent planet in close orbits. The proposal Phobos-Deimos The former impactor would have been roughly the same size as the asteroid. Vesta– the second largest inhabitant of the Handheld Asteroid Belt after the dwarf planet Ceres. Vesta sports a diameter of 326 miles, while Ceres it is approximately 587 miles wide.

“We use state-of-the-art models to demonstrate that a Vesta-a-CeresThe small impactor can produce a disk consistent with the formation of the small moons of Mars. The outer portions of the disc accumulate in Phobos Y Deimos, while the inner portions of the disk accumulate in larger moons that eventually rotate inward and are assimilated on Mars. The larger impacts defended in earlier work produce massive discs and more massive interior moons that prevent the survival of tiny moons such as Phobos Y Deimos, “ Dr. Julien Salmon explained on April 16, 2018. SwRI press release. Dr. Salmon is a research scientist at the SwRI.

These new findings are important for the Japan Aerospace Exploration Agency (JAXA) Mars Moons eXploration Mission (MMX), which is scheduled to launch in 2024. MMX It will include an instrument provided by NASA. Tea MMX The spacecraft will visit the two small moons of the red planet, as well as land on the surface of Phobos in order to obtain a surface sample that will be returned to Earth for study in 2029.

“A main objective of the MMX mission is to determine the origin of the moons of Mars, and having a model that predicts … the composition of the moons … would provide a key constraint to achieving that goal, “explained Dr. Canup on April 16, 2018. SwRI press release.