NASA has officially announced the completion of the InSight spacecraft, which has been on the surface of Mars for four years. During this time, he collected detailed information about the internal structure of the planet, its liquid core, residual magnetic field, recorded hundreds of marsquakes. About the results of the mission – in the material RIA Novosti.
InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is the first robotic module in the history of astronautics designed specifically to study the geology of another planet. Its main instrument is the SEIS seismometer, which records internal tectonic activity and meteorite impacts.
At the boundaries of the inner layers of rock with different densities, the speed of seismic waves changes, part is reflected and returns to the surface. Based on these data, you can get an idea about the structure of the planet.
Seismographs have been on Mars before, but on board vehicles, which means they could erroneously register the vibration of the hull or other instruments. In addition, they were sensitive to wind and deformed from heat. SEIS was placed directly on the surface of the planet and covered with a special casing.
On November 26, 2018, InSight landed on the Elysian Plain, and in April 2019, SEIS recorded the first quake. By May 2022, he had already recorded 1313 seismic events. Most of them are surface shocks, the waves from which propagated only in the Martian crust. But there were also deeper, low-frequency ones, according to which geophysicists determined where the mantle and core are located.
It was previously believed that all internal tectonic activity on Mars ceased three billion years ago and since then only isolated volcanoes have been active there. Now it turned out that geologically it is a living planet. The thermal and geochemical evolution of matter continues in the depths.
This made it possible to understand the nature of the Cerberus furrows crossing the Elysian plain, 1500 kilometers from the landing site. After studying the InSight data, scientists came to the conclusion that we are talking about tensile cracks in the central part of the dome that formed above a mantle plume rising to the surface – a giant “drop” of molten deep matter.
Thus, it was established that under the Elysian Plain, the youngest volcanic region of Mars, where large eruptions have occurred more than once over the past 200 million years, a magma formation center is still operating. In addition to purely geological interest, this is also important for astrobiologists, since the probability of the origin of life on the planet directly depends on its geodynamic systems.
Mars is like a giant egg
To clarify the phase state of matter inside Mars, an experiment called RISE (Rotation and Interior Structure) was conducted. The InSight instruments recorded vibrations of the planet’s shells associated with movement around the Sun, just as you can determine by the rotation of an egg whether it is raw or boiled: the less the speed changes under the influence of external forces, the more liquid the core.
At the station, which remained in one place, there were radio signaling facilities that made it possible to accurately measure orbital parameters. Calculating the moment of inertia of the planet, scientists have determined that Mars, like the Earth, has a liquid core with a diameter of about 3660 kilometers, consisting mainly of iron and nickel. Compared to Earth, it has more light elements such as hydrogen and sulfur.
Magnetic pulse of Mars
Soviet orbiters of the Mars series detected a magnetic field around the planet about 500 times weaker than the earth’s. And it is extremely unstable, the local tension can differ by 1.5-2 times, and the magnetic poles do not coincide with the physical ones.
This indicated that the iron core is inactive relative to the crust, that is, the mechanism of the planetary dynamo, as on Earth, does not work on Mars. There-fore, the Martian magnetic field was considered residual – partially preserved in the magnetization of rocks from those times when the bowels were more active.
InSight is the first lander with a magnetic sensor. And then he, too, gave a surprise. It turned out that the magnetic field is an order of magnitude stronger than thought, and is constantly changing. Since September 2019, devices have registered strange magnetic pulses and intensity fluctuations several times.
NASA notes that it is still difficult to say what causes fluctuations in the local magnetic field on Mars. It remains to be compared data from InSight and the automatic interplanetary station MAVEN (Mars Atmosphere and Volatile Evolution), which monitors the atmosphere over the landing site. It is assumed that positive magnetic field anomalies are associated either with a nearby massif of older rocks, or with an electrically conductive layer below the surface containing water or solid ice particles.
It also turned out that some fluctuations are repeated every day. Perhaps the Martian magnetic field is influenced by the Sun, which throws out streams of charged particles – the solar wind. On Mars, unlike Earth, there is no global magnetic field, and it reaches the surface.
Enemy number one
It was clear in advance that the main factor limiting the resource of the apparatus is the Martian dust deposited on the solar panels. The cleaning system would have made the structure too heavy. It was believed that the planned period of two years InSight will work and so.
The problems arose in April 2021. After another dust storm, the apparatus fell into emergency hibernation. In May, the team took a number of actions to clean up the panels and InSight resumed operations.
In January 2022, the device went into safe mode again due to a dust storm. Most features have been disabled.
On Sunday, December 18, communication with the station was interrupted. The next day, NASA reported that SEIS had run out of power. The end of the mission was marked with a farewell photo showing the lander with solar panels covered in a thick layer of dust and a free-standing seismometer. Perhaps when people get to Mars, they will clean the device and it will work again.