The National Aeronautics and Space Agency (NASA) confirmed on Wednesday, Nov. 11 that one of Mars' moons Phobos is showing early indications of structural damage that may potentially lead to total destruction.
The culprit of the possible demise? Its host planet.
In a news release issued by NASA, the agency explained how the red planet is gradually destroying one of its own moons and pointed out three main factors influencing the occurrence.
Visible Grooves
Experts have long believed that the apparent grooves on Phobos were caused by a powerful collision with an asteroid that also created the Stickney crater, a wide basin nearly six miles in diameter. The impact was so forceful that it nearly shattered Phobos, experts say.
In a recent analysis, scientists were able to detect that the grooves don't spread outward from the crater, but rather emanate from another focal area nearby.
The finding led to a new theory that the grooves are formed by tiny debris traveling from Mars and smashing straight into Phobos. The close distance of the two is said to make the impact more detrimental to Phobos.
Terry Hurford from NASA's Goddard Space Flight Center said that the first indicator of Phobos' failure is the generation of these grooves.
Close Distance Means Greater Stress
Now, the tidal forces created by Mars on Phobos is being considered as a major reason for the moon's visible grooves. The two celestial bodies mutually pull one another, just like the Earth and its moon.
Phobos orbits only about 3,700 miles atop the red planet. This distance is recognized as the closest planet-moon relationship in all of the solar system. For comparison, Earth's moon orbits approximately 238,855 miles above its mother planet. Aside from that, the Earth's moon is also said to persist in distancing itself away. The situation of Phobos and Mars is completely different as Mars extends its pulling action on its moon at 6.6 feet per century.
The main implication of the close distance between Mars and Phobos is that the tidal forces being received by the latter generate more stress that is sufficient to damage the satellite's surface. This also matches with observations that some of the grooves are younger than others, which also signifies that the process is ongoing.
Phobos' Structure
Planetary scientist Erik Asphaug from Arizona State University said new computer models also suggest that the internal part of Phobos is more delicate than its exterior, which is slightly cohesive and partially elastic.
Hurford and Asphaug applied the model to recreate the tidal waves produced by Mars. The results showed that the locations of highest stress on the moon's structure were consistent of Phobos' grooves. At present, however, experts still cannot predict how long the thin surface of Phobos could hold the entire moon together.
"We can't image those distant planets to see what's going on, but this work can help us understand those systems, because any kind of planet falling into its host star could get torn apart in the same way," said Hurford.
The details of the report were presented in the annual Meeting of the Division of Planetary Sciences of the American Astronomical Society on Tuesday, Nov. 10.
