Liquid core of Mars to generate a magnetic field between 4.5 and 4.1 billion years ago, as well as 3.7 billion years ago — before and after the formation of large plains. Perhaps, between these periods the magnetic Dynamo was active. To such conclusion came the scientists, after analyzing the data of the spacecraft MAVEN. Article published in Science Advances.
The existence of a global magnetic field is closely linked to the evolution of the internal structure of planets, their surfaces and atmosphere. Such a field is born thanks to the convection flow in the liquid conductive core, a process called magnetic Dynamo. The study of the magnetization of rocks on the terrestrial planets opens a window into the early history of these heavenly bodies — because imaging acquired in the ancient field, there remains billions of years.
Mars now has no global magnetic field. However, the observations made by the spacecraft Mars Global Surveyor (MGS) Mars from orbit, helped discover the planet of rock, which are 4.2 to 4.3 billion years ago magnetizable field created by the liquid core of Mars. In the crust of the Martian plains of the shock origin Hellas, Argon and ISIS, which was formed 3.9 billion years ago, magnetism was not possible, at this time the magnetic Dynamo had already stopped.
Anna Mittelholtz (Anna Mittelholz) from the University of British Columbia and her colleagues from USA and France analyzed data from nighttime observations made by the probe MAVEN at altitudes of less than 200 kilometers, and found a weak magnetic field on the Northern plains of Mars, whose age is estimated in 4.5 billion years — this lowland is one of the oldest parts of the terrain on the red planet. It should be noted that the data collected by the MGS magnetometer apparatus in the early 2000-ies has already been pointed out the weak magnetization of rocks in this area, but these results was not sufficiently accurate, the signal was at the limit of the noise threshold. More modern equipment has allowed MAVEN to uniquely identify the presence of a magnetic field.
In addition, the researchers found the magnetic field on the plain Lukus, which was formed less than 3.7 billion years ago — much later than a large plain shock origin in the cortex where the magnetism is absent. Planetary scientists believe that “silenced” during the formation of the plains of Greece, Argon and ISIS Dynamo could be renewed for the period of education of the plains Lukus, or it was active the whole time — a strong shock of the events that gave rise to a large plain, simply threw them with fragments of bark containing magnetic materials. It is known that the formation of craters with a diameter of up to 500 kilometers leads to the release of the crust from a depth of 50 kilometers. On the three Martian plains, the average diameter of the craters varies from 750 to 1400 miles — this suggests that they formed their punches threw the crust with even great depth and very effectively relieved these areas from magnetised rocks.
If the magnetic Dynamo on Mars was active all the time from 4.5 to 3.7 billion years ago, or resumed for a while about 3.7 billion years ago, it would more accurately represent the processes that could affect the planet’s surface. For example, Martian valleys — evidence of water on the planet — is formed between the niskim and early-Hesperia periods, i.e. about that time, when a plain Lukus, and hence there was Dynamo. Water circulation in the crust in the presence of magnetic fields could lead to hydrothermal changes that could strengthen magnetised and remagnetization magnetic minerals. Studies using Rovers and missions, shipping samples from the surface of Mars to Earth will help to confirm findings of Mittelholtz and her colleagues.
Previously we described how machine MAVEN saw proton auroras on Mars. For the study of the internal structure of the red planet meets the apparatus of InSight — and he has already discoveredthat Mars is seismically active. In addition, more recently, InSight has recorded an Eclipse of the Sun by Phobos.