Moons of Mars
© Vladimir Kalanov,
website"Knowledge is power".
Phobos (left) and Deimos (right) are the two known moons of Mars
As already mentioned, Mars has two natural satellites called Phobos and Deimos. The main characteristics of the satellites are given in the table:
| Satellite | Characteristics | Quantitative indicators |
| Phobos | Opening time | 08/12/1877 |
| Dimensions | 27x21x19 km | |
| Period of circulation | 7 hours 39 minutes | |
| Distance to Mars | 9400 km | |
| Average density | 2 g/cm³ | |
| Deimos | Opening time | 08/10/1877 |
| Dimensions | 15x12x11 km | |
| Period of circulation | 30 h 17 min | |
| Distance to Mars | 23400 km | |
| Average density | 1.7 g/cm³ | |
Small satellites of Mars are irregularly shaped celestial bodies, very similar to asteroids. The largest size of Phobos is 27 km, and Deimos is 15 km. the orbits of both satellites are inclined by approximately 2° to the plane of the Martian equator. Phobos is 9400 km away from Mars on average and has a very short period of revolution - 7 hours 39 minutes, i.e. during the Martian day, he circles the planet three times. Deimos is 23,400 km away from Mars, and it takes 30 hours and 17 minutes to fly around Mars, i.e. longer than a Martian day. Like the Moon, turned to the Earth by one side, both satellites of Mars are always turned to it by the same side. Numerous craters are visible on the rocky surface of the satellites. The largest of them, with a diameter of about 10 km, is located on Phobos. Astronomers associate the origin of such a huge crater with the likely collision of Phobos with some large celestial body. No craters larger than 2.3 km in diameter have been found on Deimos. Based on the density of craters, their age is determined at 3 billion years.
Images of Deimos (left) and Phobos (right). The huge crater Stickney is visible on Phobos.
Hypotheses of the origin of the satellites of Mars
There are two hypotheses about the origin of the satellites of Mars. The first is that both satellites, formerly asteroids, were captured by the gravitational field of Mars and have been its satellites for several billion years. According to the second hypothesis, the satellites of Mars were once part of its mass, broken off as a result of a collision with some large celestial body. This hypothesis seems more logical because the orbits of the satellites are low, approaching a regular circle in shape, and their planes almost completely coincide with the plane of the orbit of Mars (the inclination is only 2 °).
The American astronomer B. Sharpless in 1945 discovered the so-called secular acceleration in the motion of Phobos. This means that Phobos is moving in a gentle spiral, gradually approaching the surface of Mars. Approximately the same, in spiral orbits, artificial satellites of the Earth move. In the upper layers of the earth's atmosphere, the satellite slows down and descends, and approaching the Earth accelerates the movement of the satellite. The atmosphere of Mars is so rarefied that at the height of the orbit of Phobos, its effect on the satellite is practically absent. However, secular acceleration exists.
The famous Soviet astrophysicist I.S. Shklovsky in 1959 decided to calculate the conditions under which deceleration in the upper layers of the Martian atmosphere can lead to the motion of a satellite in a gentle spiral. The estimated height was taken as 6000 km. the result was sensational: the flight of Phobos in a gentle spiral is possible if it is ... hollow, i.e. empty inside, like artificial earth satellites. It turns out that Phobos is also an artificial celestial body made by some kind of intelligent beings?!
But the sensation did not work, because with the help of photographs transmitted to Earth by an automatic interplanetary station "Mariner-8" it was finally established that Phobos and Deimos are solid blocks of irregular shape. Soon the Soviet scientist N.N. Parisky found an explanation for secular acceleration. According to this scientist, due to the proximity of Phobos to Mars, tidal waves of soil arise on the surface of the planet in much the same way as it happens on Earth from. The attraction of the moon leads to the fact that the earth's crust rises and falls almost half a meter twice a day following the movement of the moon. Although the mass of Phobos is small, it is so close to the surface of Mars that it creates tidal waves (they are called tidal humps) much smaller than those that arise on Earth from the movement of the Moon, but still sufficient to influence the movement of Phobos. The tidal wave on the Earth, due to friction and stress in the Earth's crust, does not keep up with the Moon and lags behind its movement by about a quarter of the Earth's circumference. Something similar happens on Mars. The attraction of tidal humps slows down Phobos. Deimos has not seen a secular acceleration. How sensitive is the deceleration of Phobos by tidal humps? According to calculations, if such a movement continues, then Phobos may fall to the surface of Mars in ... 15 million years. To what extent such alarming predictions are correct, future research and calculations will show. Launches of Soviet automatic stations "Phobos-1" and "Phobos-2", carried out in 1988-1989 to study the movement of the satellites of Mars, ended in failure.
Scientists cannot agree on the origin of Mars' moon Phobos. One of the versions says: Phobos is of artificial origin. Both moons of Mars were discovered by the American astronomer Asaph Hall in 1877. He named them Phobos and Deimos, which in Greek means "fear" and "horror".
One of the satellites of Mars, Phobos, is located 9400 km from Mars. It has an irregular shape, not typical for cosmic bodies, and, like the Moon, it always faces the planet with only one side. Its dimensions are 26.6 × 22.3 × 18.5 kilometers.
According to one of the theories about the origin of the Martian satellite, Phobos is an asteroid captured by the gravity of the planet. There are many similar celestial bodies in the main asteroid belt between Jupiter and Mars.
According to another theory, Phobos broke away from Mars when the planet collided with an asteroid, or some other catastrophe on a planetary scale. This is partly confirmed by the discovery of a large amount of phyllosilicate in the satellite rock. This mineral, which forms only in the presence of water, was previously discovered on Mars.
But there is also a theory about the artificial origin of Phobos. The researchers managed to find out that under the shell of the satellite there is a huge empty space. The conclusion about the presence of empty space was made by two independent groups of scientists, comparing information about the mass of Phobos and its gravitational force. These data were presented by the European Space Agency's Mars Express Orbiter, launched on July 2, 2003. Russian rocket from the Baikonur Cosmodrome.
July 12, 1988 Two Soviet space stations launched to Mars - Phobos-1 and Phobos-2. Communication with the station "Phobos-1" for an unexplained reason ceased on September 2 of the same year, and "Phobos-2" managed to achieve a given orbit.
March 27, 1989 the station began approaching the moon of Mars. For some unknown reason, communication with him was interrupted, and it was not possible to restore it. He didn't seem to give any information.
Back in the seventies of the last century, the American Viking spacecraft transmitted photographs of Phobos to Earth. And some of them show clear chains of craters. If these craters are of meteorite origin, then the meteorites fell to the surface in a very strange way. One by one a clear line. At first, experts jokingly said that he had been bombed. Then this version began to be considered quite seriously.
After it was established that there were huge voids inside, the Soviet astrophysicist Shklovsky put forward the then-fantastic assumption that Phobos was nothing more than a giant space station.
Marina Popovich immediately agreed with him. She also spoke about what happened before Phobos-2 interrupted communication with the Earth. He managed to transfer several images. One shows an elliptical shadow on the surface of Mars. And it is visible not only in the usual, but also in the infrared range. That is, it is not a shadow, because a shadow cannot be warm.
In the second image, near the surface of Phobos, a gigantic cylindrical object is clearly visible. It was shaped like a cigar, about 20 km long and 1.5 km in diameter. According to Marina Popovich, it was this object that destroyed the station. Destroyed just at the moment when Phobos-2 was about to send instruments to the surface of the satellite for research.
The pictures were immediately classified.
American astronaut Edwin Aldrin, speaking on one of the American television channels, said that it is necessary, and first of all, to visit the satellite of Mars, Phobos. According to him, on the surface of Phobos is "a strange contraption, some kind of monolith." He said that everyone who saw the photo of this monolith does not doubt for a second that it was installed by someone.
NASA declined to comment on the image of a hemisphere the size of a five-story building, which shows numerous depressions. It was this object that Aldrin called the monolith.
Only the representative of the Canadian Space Agency, Dr. Alan Hildebrand, spoke about this. And he said a rather strange phrase, the meaning of which boils down to the fact that if you manage to get to the monolith, then you may not need to fly anywhere else.
After this interview, many scientists concluded that NASA had some very important information. And he tries to hide them.
Every year Phobos gets closer to the surface of the planet. Sooner or later, the gravity of Mars is sure to tear it apart. But until this happens, there is time to explore this mysterious and enigmatic satellite. So far there is.
Unfortunately, Russia's attempt to send an apparatus to study the mysterious Phobos ended in failure. Accident?
The Russian interplanetary station "Phobos-Grunt" could not have become a victim of the asteroid radar sessions that American scientists conducted during the launch of the probe and immediately after it, according to the calculations of Canadian amateur astronomer Ted Molczan (Ted Molczan).
A previously unnamed source in the rocket and space industry told the Kommersant newspaper that Phobos-Grunt could be in the range of the American radar on the Pacific Kwajalein atoll, which at that time was tracking the trajectory of one of the asteroids. The impact of a powerful radio pulse, according to this version, could lead to a failure in the electronics, due to which the probe did not turn on the marching propulsion system and did not switch to the flight path to Mars.
In the period of November 8-9, at the same time that Phobos was launched, American scientists really conducted an experiment on the radar of the 400-meter asteroid 2005 YU55, which approached the Earth at a distance of 325 thousand kilometers - 60 thousand kilometers less than the lunar orbit. However, only the 70-meter radio telescope at Goldstone and the Arecibo radio telescope (Puerto Rico) participated in it.
"I'm still looking for evidence of any Kwajalein Atoll radars being involved, but even if they were, the asteroid was over the horizon from the atoll's perspective during both Phobos-Grunt flybys," Molchan wrote in the post. on the satellite watcher website.
Thus, even if the radars on Kwajalein participated in the 2005 YU55 radar program, at the moment when Phobos-Grunt passed over them, the radars had nothing to “look at” - the asteroid was invisible to them.
The Phobos-Grunt Automatic Interplanetary Station (AMS) - the first Russian AMS in 15 years designed to deliver soil samples from a Mars satellite - was launched from the Baikonur Cosmodrome on the night of November 9. Both stages of the Zenit-2 SB launch vehicle worked normally, but the propulsion system of the interplanetary station did not turn on and could not transfer the device to the flight trajectory to Mars. months to fly around the Earth.
On Sunday, January 15, the fragments of "Phobos" fell to Earth, but there is still no clarity with the time and territory of the fall of the fragments of the station.
The Ministry of Defense of the Russian Federation reported that the wreckage of the station at 21.45 Moscow time fell in the Pacific Ocean - 1250 kilometers west of the Chilean island of Wellington. This information was confirmed by another source of RIA Novosti in law enforcement agencies.
However, a source in the rocket and space industry of the Russian Federation, citing data from civilian Russian ballistics, told RIA Novosti that fragments of the apparatus could fall between 21.40 Moscow time and 22.20 Moscow time with the coordinates of the central point 310.7 degrees east longitude (equivalent to 49.3 degrees west longitude in the 180-degree system) and 18.2 degrees south latitude.
After the explosion of "Phobos-Grunt" in the dense layers of the Earth's atmosphere, the dispersion and fall of debris began, most likely, over the Atlantic Ocean and continued over a wide strip, including the territory of the Brazilian state of Goiás.
Roskosmos has not yet given official information about the place and time of the fall of the station.
Secret...
This tiny satellite of Mars with the wonderful name “Fear”, which is exactly how Phobos is translated, turned out to have so many secrets that it’s amazing how it hasn’t crumbled under their weight yet ... Oh, it doesn’t look like a satellite, but looks like a spaceship. But whose?
To start a story about the secrets of Phobos is stupid without presenting his own photo. Here he is handsome: 
And looking at this image, by the way, made on March 7, 2010 by the NASA Mars Express spacecraft, we face the most obvious subject of controversy. What is the secret of the numerous stripes on the surface of this cosmic body? The official explanation of this phenomenon, I think, is known to everyone, but still I will voice it.
Of course, these are traces of meteorite impacts! Traveling through space, what kind of garbage you will not meet. It's just that these "traces" are strange. For some reason they run parallel and perpendicular to each other. Oh, yes, meteorites - what accuracy ... Have you seen such traces on any other body? I have not personally met.
But if, according to the hypothesis, we assume that Phobos is nothing but a spaceship, the stripes find a completely reasonable explanation. Take a look at the enlarged image: 
This is nothing more than a frame and bulkheads. The skin of the ship has fallen into disrepair for so many years, and the internal parts have begun to gradually "bare"
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The next mystery of Phobos lies in the very fact of the discovery of the latter. Two brothers (Horror (Deimos) and Fear) were discovered in 1877 by Asaph Hall. This is despite the fairly advanced technology for observing the planets and their satellites at that time. From this fact, I.S. Shklovsky concluded that Mars acquired satellites quite recently. Moreover, he was also sure that Phobos was a spaceship.
In 1989, already our apparatus "Phobos-2", being in those parts and carrying out its measurements, received data that the satellite of Mars was one-third hollow. And the aforementioned Mars Express confirmed these data. But that's not all.
The notorious MARSIS radar complex (as we remember, such devices were developed and implemented thanks to the SETI project), having decided to “feel” Fear with its radio waves, received a very interesting reflected signal. This signal ambiguously indicates the presence of voids in the body of the satellite, and not just any, but geometric voids!
Have you ever heard about the so-called Monolith on the surface of Phobos, discovered in 1998 by E. Palermo? Baz Aldrin himself once mentioned him.
This is what this mysterious object looks like: 
One way or another, Phobos is clearly an artificial satellite. But what civilization built it? And this, friends, we would have learned this year, but again some “case” did not allow “Phobos-Grunt” to leave the boundaries of our planet ...
According to Wikipedia, now we have to wait until 2020! Directly some kind of evil rock is pursuing spacecraft sent to Mars! First, the Mars Observer, which was supposed to confirm or deny the presence of the famous Face on Mars in the Cydonia region, now Phobos-Grunt is just an accident after an accident ...
Huge spaceship orbiting Mars
Astrophysicist Dr. Iosif Samuilovich Shklovsky calculated the orbital motion of the Martian satellite Phobos, and came to the startling conclusion that the moon of Mars is artificial, hollow, and in fact is a giant ship.
Fear and horror
Mars has two satellites - Phobos and Deimos, whose names translate as Fear and Horror. Since Mars is named after the god of war, the names of the satellites seem appropriate. Both satellites were discovered in 1877 by the American astronomer Asaph Hall, who never suspected that they could be artificial. Both moons are extremely strange, especially Phobos. Shklovsky puzzled over them for a long time. Phobos and Deimos.
Deeply disturbing facts
Two facts deeply disturbed Shklovsky.
First, both satellites are too small. No planet in the solar system has such small moons as Mars. They are unique.
Secondly, he was worried about their origin. Were they simply asteroids caught in the gravity of Mars? No and no! Their entire orbit was wrong. And they are very close to Mars. Too close. But the most amazing thing is that Phobos originally changes its speed from time to time.
Unbelievable, but it is a fact!
Phobos is shaped like an interstellar spaceship
Russian astronomer Hermann Struve spent months calculating the orbits of the Martian moons with extreme precision in the early 20th century. However, Shklovsky astutely noted that over time, the orbital speed of the mysterious moon and its position no longer corresponded to the mathematically calculated position.
After a long study of tides, gravitational and magnetic forces, Shklovsky came to the inevitable conclusion that no natural causes can explain the origin of two strange moons and their strange behavior, in particular, Phobos
The orbit of this fantastic moon was so peculiar, and so strange, that Phobos could have been a gigantic spaceship.
Any possible cause was carefully examined, and strongly rejected. Either alternative explanations had no evidence, or they did not fight with mathematical calculations.
So Phobos was accelerating with the loss of altitude, but perhaps it was affected by the outer edge of the thin Martian atmosphere? Could the atmosphere actually cause the deceleration? 
Phobos is empty like a tin can
During an interview discussing the features surrounding Phobos, Shklovsky said, “In order to produce a sufficient decelerating effect, and taking into account the extremely rarefied atmosphere of Mars at altitude, Phobos must have an extremely low mass, (which it does have), that is, a very low density, about a thousand times less than the density of water.
Such a low density, which is even lower than the density of the earth's cloud, should have dissipated Phobos without a trace long ago.
“But could its apparent hardness have such an extremely low density, perhaps less than that of air? Of course not! There is only one configuration in which the shape of Phobos and its extremely low density can be consistent. Here we come to the conclusion that Phobos is a hollow, empty body, reminiscent of an empty tin can.
In terms of its goals and performance, the Apollo lunar module was, in fact, the same tin can, only of course much smaller than Phobos.
“So, can a celestial body be hollow? Never! Thus, Phobos must be of artificial origin, and be an artificial satellite of Mars. The peculiar properties of Deimos, although less pronounced than those of Phobos, also indicate its artificial origin.
Alien ships the size of a small Martian moon? The so-called Martian face is nothing compared to this!
The US Naval Observatory itself gave weight to the words of the Russian astrophysicist, saying that Dr. Shklovsky calculated quite accurately that if the acceleration of Phobos is true, then the Martian moon must be hollow, since it lacks the weight inherent in a natural body, and behavior consistent with this weight .
Thus, even the most august American institution admitted that an alien ship could be in orbit around Mars... the origin of the strange object and its ultimate goals are still completely unknown.
Speculation about its purpose ranges from a giant Martian space observatory, to a half-finished interstellar spacecraft, or even a huge planet-killing bomb left over from an interplanetary war many millions of years ago.
Phobos ... an artificial satellite
The prestigious European space agency has said that Phobos, the mysterious Martian moon, is artificial. At least one third of it is hollow, and the origin of the satellite is not natural, alien in nature. ESA is the analogue of NASA in Europe. Could this revelation motivate NASA to uncover its secrets? Don't count on it...
Famous astrophysicists considered Phobos to be artificial.
Astrophysicist Dr. Iosif Samuilovich Shklovsky first calculated the orbital motion of Phobos, a Martian moon. He came to the inevitable conclusion that the Moon is artificial and hollow, in principle, a huge ship.
A Russian astronomer, Dr. Herman Struve, spent months calculating the orbits of two Martian moons with extreme accuracy in the early 20th century. After studying the astronomer's report, Shklovsky realized that over time, the orbital speed and position of Phobos in space do not correspond mathematically to Struve's predictions.
After a long study of tides, gravitational and magnetic forces, Shklovsky came to the firm conviction that there are no natural causes that could explain the origin of the two odd moons or their strange behavior, in particular, what Phobos demonstrates.
The moons were artificial. Someone or something created them.
How Mars appeared many millions of years ago
During an interview about the mysterious Martian moon, Shklovsky explained: "There is only one explanation in which the characteristics are consistent, the constancy of Phobos' shape and its extremely low average density can be reconciled. It must be assumed that Phobos is a hollow, empty body, reminiscent of an empty tin can."
For decades, most mainstream science ignored Shklovsky's breakthrough until the ESA began to look closely at the odd little moon.
An abstract ESA study, which appeared in the peer-reviewed journal Geophysical Research Letters, shows that Phobos is not what astrophysicists and astronomers for generations thought it was: a trapped asteroid.
"We report independent results from two subgroups of the Mars Express Radio Science (MaRS) team who independently analyzed and tracked the data for the purposes of determining the consistent gravitational pull of the moon Phobos on the MEX spacecraft, and hence the mass of Phobos. New values for the gravitational parameter (GM = 0.7127 ± 0.0021 x 10 - km³³/s²) and Phobos density (1876 ± 20 kg/m³) provide meaningful new limits on the corresponding body porosity range (30% ± 5%), provide a basis for improvement interpretation of the internal structure. We concluded that the interior of Phobos probably contains large voids. When considering various hypotheses about the origin of Phobos, these results are not consistent with the assumption that Phobos is a captured asteroid."
Casey Kazani writes in ESA: Mars' Moon Phobos is 'Artificial' that "... the official ESA website Phobos contained specific scientific data, from various points of view, which thoroughly "supports the idea that the radar signals appear to be coming back from within" a huge geometrically. .. ... hollow ship". The coincidence of all these three independent Mars Express experiments - "imaging", "internal mass distribution", "(tracking) and "internal radar imagery" now leads to the conclusion that "Phobos inside is partially hollow, with an internal, geometric void that Phobos is artificial."
In other words, Phobos is not a natural satellite, it is not a "captured asteroid", and the object is hollow. This is exactly what Dr. Shklovsky identified back in the 1960s.
Phobos was artificially built and put into Martian orbit ... how, by whom?
Data show Phobos is not natural. At present, there is not enough information to discover exactly what the Martian moons are, but there are some intriguing speculations.
1. This giant spaceship could have been built as an orbital station or a space observatory.
2. This is a generated ship that came from another star system and was placed in a parking orbit around Mars.
3. The moon was built in the orbit of Mars by interstellar travelers, but was not completed.
The fourth possibility is more sinister and disturbing.
4. This is a functional (or non-functional) giant killer planet, a space bomb, possibly left over from some interplanetary conflicts in the surrounding space millions of years ago. (Some researchers actually propose this hypothesis.)
Alien ship, superbomb or unfinished project?
Regardless of the state of modern Phobos, its origin and purpose are completely unknown.
Theories of the origin and nature of the satellites of Mars, the history of their research was accompanied by hoaxes, rumors and legends. Including Phobos and Deimos were called alien ships. And scientists have suggested that the number of satellites of the Earth's twin in general could be different.
Martian moons Phobos and Deimos Prediction of the moons of Mars
For the first time, the assumption that Mars has two accompanying bodies was put forward by the German astrophysicist Johannes Kepler in 1611. He allowed this, based on the mention in the writings of Galileo Galilei of observations of a triple planet. Later this record was interpreted as a description of Saturn with its famous rings.
Despite the wrong premises, Kepler's assumption turned out to be true. To perpetuate the memory of the astronomer, craters on Mars and on the Moon are named after him.
Calculations of the physical parameters of the satellites of Mars, even before their discovery, were given by Jonat Swift in 1726 in the book Gulliver's Travels, based only on his imagination. 8 craters on the surface of Phobos are named after the characters of this work.
Asaph Hall discovers moons of Mars
In the 16th century, all the developed observatories of Europe were puzzled by the search for the moons of a neighboring planet. But Deimos and Phobos were officially discovered on August 11 and 17, 1877 respectively in the USA by Asaph Hall. It was possible to do this during the period of maximum convergence of our planet with its neighbor, which occurs every 15 years.
How did the moons of Mars get their names?
Phobos and Deimos received their official names in February 1878 after a long search for successful names. He corresponded with many representatives of the scientific world, and among the many proposed names, he chose the option of Henry George Madan. He, in turn, took the name from the Homeric Iliad. According to another version, these names were suggested by an unknown schoolgirl from the UK.
Among the planets of the solar system, asteroids, stars and other cosmic bodies, many names are taken from ancient mythology. The red planet, because of its aggressive surface color, was symbolically named after the ancient Roman god of bloody war. Mars, or, as the Greeks called him, Ares. He was considered one of the most revered gods, despite the fact that he symbolized cruelty, strength, the desire for war for the sake of pleasure. It is logical that the satellites of the planet Mars were named after the children of the god of war of Greek mythology.
According to the beliefs of the Greeks, children accompanied them with Aphrodite in all battles. Therefore, it is obvious why the satellites today are called Phobos and Deimos, that is, fear and horror.
How many moons does Mars have
How many satellites Mars had remained unknown until 1877. Despite the mathematical calculations of astrologers, suggesting the presence of bodies in the orbit of a neighbor, it was believed that the planet had no natural satellites at all, since they could not be fixed. The discovery of these objects became a sensation in the scientific world.
It has now been proven that the planet Mars has two natural satellites, called Phobos and Deimos. The first is in the inner orbit of the planet at an average distance of 9380 km, the second is two and a half times further.
Distance from Mars to its moons It seems that scientists have figured out the mystery of the origin of Phobos and Deimos - two natural satellites of Mars. For years, the potato-like shape of both moons has led scientists to believe that both of Mars' current moons are just asteroids captured by the planet in the distant past. However, this hypothesis could not explain the fact that the orbits of satellites are circular and lie close to the equatorial plane of the planet.
An alternative explanation, suggesting that these moons, each 22 and 12 km in size, were born as a result of the impact of some body on Mars, also raised a number of questions, for example, why, as a result of the collision, Mars was left with two small satellites, and not with one moon, as happened with the Earth.
In an article published in the journal nature geoscience, scientists led by Pascal Rosenblatt from the Royal Observatory of Belgium gave a convincing answer to a question that had worried scientists for decades, and came to the conclusion that
that these blocks really owe their birth to a powerful blow.
Computer simulations of how the orbits of the debris changed from this collision helped to understand this. The created animation illustrates how events developed around Mars after the catastrophic impact:
The so-called North Polar Basin is the largest basin in the northern hemisphere of Mars. It occupies about 40% of the surface of the entire planet; it is assumed to be of impact origin and apparently formed as a result of a catastrophic collision of Mars with a giant body billions of years ago. The shape and dimensions of the pool allow us to consider that it was formed as a result of a body impact,
most likely, protoplanets 2 thousand km in size.
Modeling showed that as a result of this impact, 10 20 kg of debris were thrown into space, forming a ring, the total mass of which could be 10 thousand times greater than the total mass of Phobos and Deimos. Calculations show that the formation of satellites inside the disk of debris occurs close to the inner edge of the disk, where the concentration of debris is maximum, their speeds are high, which means that collisions are frequent. However, the formation of satellites is impossible within a certain region where the gravitational influence of the planet predominates - the so-called Roche limit. This is the radius of the circular orbit of the satellite, on which the tidal forces of the planet are still balanced by the self-gravity of the satellite (in the case of Mars, 3 planet radii).
Therefore, the most ancient satellites should form at the leading edge of the disk just beyond the Roche limit. However, in the case of Mars, this is too close for the orbits of these satellites to remain stable on geologic time scales. The fact is that Mars has a low speed of its own rotation (only 24.7 hours), so all satellites rotating within the so-called synchronous radius (~ 6 radii of Mars) rotate faster than the planet itself. And this means that Mars is gradually slowing down such satellites, because each of them causes tidal humps on the planet,
and with each turn they spin it, and the satellites themselves slowly lose their orbital momentum and go out of orbit.
This is what is happening today with Phobos - it is known that the satellite is at a distance of 2.76 radii of Mars, makes a complete revolution in just 8 hours
and most importantly, it is gradually approaching the planet at a speed of 2 cm per year!
Forecasts for it are disappointing - calculations show that in the next 20-40 million years, Phobos, once in an orbit of 2 radii of Mars, will be torn apart by tidal forces and itself will create a ring of debris that will fall out in the region of the planet's equator. In the case of the Earth, apparently, everything happened exactly the opposite. The first satellites formed after a similar impact also at a distance of three radii. However, due to the fact that the early Earth rotated around its axis five times faster than now, it did not de-orbit, but threw the only Moon farther from itself.
After tracing the evolution of Phobos and Deimos over time, scientists found that both satellites most likely formed near the synchronous radius (6 R), however, to explain the appearance of the North Polar Basin, a third body was missing - a large, fairly close moon (several hundred kilometers in diameter).
Actually, this moon, with its gravity, gave birth to Phobos and Deimos, blinding them from debris in two resonant orbits.
Having done its “work”, a large third large moon (maybe Mars had other satellites, but they all went out of orbit) fell on the planet, losing orbital momentum and forming the said basin.
The existence of this third moon in Mars' distant past is a key finding in the scientists' work. Calculations show that as a result of the alleged megacollision, half of the debris comes from the material of the planet, half from the material of the impactor. Currently, Phobos has already gone inside the Roche limit, and scientists see that its surface has cracked due to the tidal influence of Mars. Scientists hope to learn about its composition with the help of the upcoming Japanese mission Martian Moons Explorer.
A few years ago, the American automatic interplanetary station discovered this strange vertically protruding object on Phobos, and it is still unknown what it is.
“When people find out about this, they will wonder: who left it there?” These words were spoken in 2009 by Buzz Aldrin, the second astronaut in history to set foot on the surface of the moon. Aldrin was referring to the oddly shaped, so-called monolith found on the surface of the Martian moon Phobos.
And he was right: the mysterious monolith has haunted many since then. There have been many theories linking this object to alien activity; a music album released this year by Les Claypool and Sean Lennon is even named after him.
So what are we dealing with?
Phobos is one of the two moons of Mars
The monolith, as scientists believe, is a large stone block, reaching, according to some estimates, 90 m in height. It is located in the center of the desert plain, which makes it especially noticeable.
But the monolith on Phobos is not a unique object. On the surface of Mars, too, there is something similar.
Monolith on Mars
The scientific community does not consider such phenomena as evidence of the existence of an advanced extraterrestrial civilization. The Martian monolith, according to scientists, is almost certainly a stone fragment of a relatively regular shape that rolled down from a nearby mountain.
Other unusual objects on Mars, such as the "floating spoon" or the "Egyptian pyramid", may have been caused by natural erosion.
Martian "spoon"
And the famous "face" on the Martian surface will no longer seem creepy if you look closely at it or consider it from a different angle.
But the monolith on Phobos has not yet been studied so thoroughly.
Perhaps this is just a rock fragment formed as a result of a meteorite impact - there is evidence of periodic asteroid activity on Phobos.
Another possible explanation is that such debris falls on Phobos from the surface of Mars, which is bombarded by asteroids from time to time. Some calculations indicate that for every million pieces of rock that dot the surface of Phobos, about 250 or more are of Martian origin.
However, it is possible that the monolith on Phobos is not related to asteroids. It may be part of the solid rock of the satellite itself, peering through a layer of stone debris. This version was presented several years ago by planetary scientists who discussed the possibility of sending an expedition to Phobos.
If the hypothesis is confirmed, perhaps the monolith will give scientists an answer to the question of the origin of the Martian satellite.
In this case, the value of the monolith will increase significantly. According to a number of scientists, Phobos is the most mysterious celestial body in the solar system.
Phobos is one of two small moons orbiting Mars. The other is named Deimos. Scientists do not fully understand how these two objects formed. Both satellites are distinguished by their small size and irregular shape; they are outwardly similar to asteroids, which once in the distant past were captured by the gravitational field of Mars. However, the features of their orbits refute this hypothesis.
According to another explanation, both satellites formed billions of years ago from the same material as Mars itself. But precise astronomical measurements show that the density of Phobos is significantly lower than that of a typical Martian rock.
The third version remains: a long time ago, Mars experienced a devastating collision with a large protoplanet, as a result of which its two satellites were formed.
A similar hypothesis explains the origin of the moon. But Phobos and Deimos are much smaller than the Moon. As a result of the collision, Mars should have had a much larger satellite.
New answers are contained in two scientific papers published in 2016. Both studies support the collision version. One of the works contains additional calculations pointing to the non-asteroid origin of Phobos and Deimos, and the second explains in detail why Mars now has only two small satellites.
According to this version, as a result of the collision, Mars did have a large satellite. Thanks to its gravitational interaction with Mars, the remaining space debris formed several smaller satellites, including Phobos and Deimos. Gradually, the height of the orbits of the large satellite and all the others - except for Phobos and Deimos - decreased until they collapsed and fell to the Martian surface in the form of debris. Thus, Mars has only two current moons.
This hypothesis could be confirmed or refuted by the proposed expedition to Phobos, the purpose of which should be to analyze the composition of this celestial body. In 2015, the American aerospace agency NASA suggested that Phobos is gradually being destroyed, as evidenced by the furrows on its surface.
However, there is plenty of time for a flight to Phobos: according to scientists, destruction does not threaten it in the next 30-50 million years.
