DEIMOS

Mars moon Deimos is about 4.5 billion years old, which is about the same age as Mars. Its distance from Mars is 23, 460 km and the diameter around this moon is 15 by 12.2 and 10.4 km. The mass of this moon is 1.8 x 10¹⁵. Its orbital period and rotational period around Mars is about 30.4 hours (30.35 exactly). Deimos has no atmosphere and no magnetic field. This moon is a non-spherical, potato- shaped moon with craters. It has a noticeably smoother appearance than Phobos. . It is the outermost moon of Mars and is the smaller than Phobos if compared. Deimos orbital is nearly circular and is close to the equatorial plane. It also exceeds the Martian solar day of about 24.7 hours by a small amount of 2.7 days. Scientists are unsure if these moons formed with the planet or were asteroids that were captured into the atmosphere around Mars.

Deimos has a nickname, “Chariot of Terror.” Deimos got its nickname from one of the charioteers of the Roman god, Mars. The name, at first spelled Deimus, were suggested by Henry Madan who is the Science Master of Eton, and the names could be found in the Book XV of the Iliad, where Ares (Mars) summons Dread (Deimos) and Fear (Phobos). In the studies of Greek mythology, Deimos also represents the name of one of the sons of Ares who also go by the name Mars. Deimos was discovered on August 12^th, 1877 by an astronomer named Asaph Hall at the United States Naval Observatory in Washington and he captured the photos at the same time while he was on a search for the Martian Moons.

With the length of only 9.9 miles it is the smallest moon of them all in the entire solar system. Deimos looks like a pockmarked chunk of rock in the orbit around Mars. At its distance of 14,573 miles this moon is more than twice as far from Mars than Phobos. In the sky it appears to be a little more than moderately bright in the Martian sky. Its irregular shape seems to resemble one of the larger asteroids in the belt located between Mars and Jupiter. Researchers suggest that this moon is composed of many of the same materials, spectra, albedos and densities as the asteroids in that belt. Deimos is a dark body that appears to be composed of C-type surface materials; such as ice and carbon-rich rock. Do you think that this moon could have possibly been an asteroid once ago?

Deimos features are unremarkable. It is a large rock potted with several craters. Most of its craters are generally smaller than 2.5 km in diameter but the largest crater is two miles in diameter and about 1/5 the size of the moon itself. Usually when a piece of meteorite hits a surface the material is thrown up creating a crate then the material falls back to the surface surrounding it which are called ejecta deposits. These deposits are not seen on Deimos, perhaps because of the Moon’s gravity is so low the ejecta escaped to space afterwards. Deimos has a thick regolith which is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials. Deimos has no evidence of surface fracturing and this may be because it is twice as far from Mars than Phobos is and it doesn’t carry the same gravitational force as do its cousin Phobos. Some say due to the far distance of this moon and because of Deimos escape velocity being at 5.6m, which is the speed needed to “break free” from a gravitational field without further propulsion; that instead of crashing into Mars it may rather move slowly further and further away from Mars, leave Mars orbit and may never been seen again.

Deimos if seen from Earth would appear as a star with the naked eye. At the brightest of this moon which is called the full moon phase, it would be as bright as Venus from Earth and at the first or third quarter it would be as bright as the star Vega (which is the brightest star in the constellation of “Lyra”, and the second brightest star in the northern celestial hemisphere, relatively close star at only 25 light-years from Earth). With a telescope an observer could see Deimos phases (1.2648 days). Deimos rises in the east and sets in the west. There is also an elapse between its rising and setting for the observer. Being that it is so close to Mars orbit it can’t be seen from latitudes greater than 82.7 degrees. Also since it phases in front of the sun (if on Mars) it is too small to create a total eclipse and would appear as a small black dot traveling across the Sun.

PHOBOS

Mars moon Phobos is also 4.5 billion years old. Its distance from Mars is 9,377 km and the diameter around this moon is 27 x 22 x 18 km. The mass of this moon is 1.1 x 10¹⁶ kg and 17 miles in length. Its orbital period is 11.1 hours and moves across the sky in 4 h 15 min or less during a Martian day and twice a day every 11 h 6 min. Phobos, which orbits so fast that it actually rises in the west and sets in the east. . Phobos also has no atmosphere and no magnetic field. It is located closer to Mars than Deimos is. It is so close to Mars that it is closer than any other moon near any other planet in the Solar System. Deimos and Phobos are both the smallest moons in the solar system but it happens to be a bit larger therefore making Deimos the smallest of them all. Phobos is Greek mythology was the other charioteers of the Roman god, Ares (Mars). It is also named after the other son of Ares and Aphrodite making the moons brothers if speaking mythological. Phobos was discovered by Hall on August 18, 1877 days after Deimos by the same person Asaph Hall.

This tiny moon is so small that it is unable to be seen above the horizon from all points on the planet. Phobos is called to be one of the least reflective bodies in the Solar System. This moon also looks as if it was an asteroid and is also composed of carbon-rich rock due to the theory of these moons once coming from the asteroid belt mentioned above. Although this moon has such a low density that it cannot possibly be pure rock. There was a Soviet spacecraft that at one time they detected gas coming from Phobos and the Astronomers didn’t know what was causing this. Also Phobos may contain a substantial reservoir of ice. This moon is too small to be rounded under its own gravity. The surface area on this moon is slightly less than the land area of Delaware and is covered with a layer of fine-grained regolith at least 100 meters thick. Phobos has many similarities with its brother moon Deimos; however this moon revolves around Mars in the opposite direction unlike Deimos.

Phobos revolves so slow that it takes 1/3 the time it takes Mars on its axis. Phobos is known to have a synchronous orbit because it is so slow and the tidal forces that this moon has cause the planet to continuously get lower every year. A synchronous orbit is an orbit in that an orbiting body has a period equal to the average rotational period of the body being orbited, and in the same direction of rotation as that body. It is estimated that in around 10 to 50 million years to either crash into Mars or break up into a ring like around the Jovian planets Jupiter, Saturn and Uranus and Neptune. It is said that once Phobos gets down to an altitude of 2,250 miles going at 1.8 miles every hundred years; above the surface of Mars that it will enter into something called a Roche limit. As this happens the tidal forces from Mars will cause the moon to tear apart and spiral around the planet creating a ring.

Phobos is heavily cratered, it is non-spherical and it is a potato-shaped moon with a huge crater at the other end. That crater has been named Stickney which is the name of the wife of the guy who discovered the moons of Mars (Asaph Hall). Stickney is 6 miles wide and is nearly 1/3 of the size of its whole body (Phobos). The impact from the object that created Stickney caused streak patterns across the moon itself. It is also said that there is fine dust filled inside, with evidence of boulders sliding down its sloped surface of this crater. There is another two large craters named Hall and Roche which are half the size of Stickney. Phobos also has surface fractures. This could have come from the giant impacts that formed the large craters and the after effects of objects hitting into the moons. Also these fractures could have come from the gravitational pull effects of Mars.

Phobos has been known to have been gouged and shattered by giant impacts and thousands of meteorites during its life next to Mars. Phobos surface is so bad that Observations by Mars Global Surveyor indicate that this moon has been pounded into powder by eons of meteoroid impacts. This has also started landslides that left dark trail markings in and outside of the steep slopes of the craters. There are also grooves are typically less than 30 m deep, 100 to 200 m wide, and up to 20 km in length on the surface of Phobos. These grooves were formed as crater chains, and all of them fade away as the peak of Phobos is approached. They have been grouped into 12 or more families of varying age, presumably representing at least 12 Martian impact events. But it is not known how any kind of material stuck to an object with almost no gravity.

There have been efforts to find out the temperatures on this moon unlike Deimos. Only because this moon is so close to Mars that the temperature can be estimated and from there information can be built around it. The temperature varieties so much that the sunlit side of the moon is similar to a winter day in Chicago and on the dark side of the moon the climate are as harsh as the weather in Antarctica. The highest temperatures on this moon are at 25 degrees Fahrenheit and the lowest is -170 degrees Fahrenheit. These temperatures are subject to such an intense change that the surface of Phobos is unable to retain heat.