How Mars Lost its Oceans

It has long been recognized that Mars once had oceans due, in part, to a protective magnetic field similar to Earth’s. Nevertheless, the electromagnetic field disappeared, and a new research study may lastly be able to explain why.

Scientists recreated conditions anticipated in the core of Mars billions of years ago. They found that the behavior of the molten metal believed to be present most likely generated a brief magnetic field that was predestined to vanish.

Whether it is due to science fiction or the fact that you can see it with your very own eyes from Earth, Mars has captured the imagination of individuals for centuries. It is one of the closest planets to us and has been studied with all types of scientific instruments aboard the several unmanned space probes that have explored it and continue to do so.

However, despite this, there are some big unanswered questions regarding Mars– the answers to which can even shed light on our distant past and future, since Earth, Mars, and all our neighboring planets were birthed of the very same cosmic things.

How did Mars’ oceans form?

Some prominent questions about Mars have already been answered. We know that several visible features of Mars are proof that it used to have oceans and a protective magnetic field. However, in particular, one question had gotten on the mind of Professor Kei Hirose from the University of Tokyo’s Department of Earth and Planetary Science: There must have been an electromagnetic field around Mars, so why was it there whatsoever? Why was it there so briefly? Compelled to address this question, a group led by Ph.D. student Shunpei Yokoo in the Hirose lab explored a unique method to test something so distant from us in both time and space.

” Earth’s electromagnetic field is driven by inconceivably big convection currents of molten metals in its core. Magnetic fields on various other planets are believed to function the same way,” said Hirose. “Though the internal composition of Mars is unknown, proof from meteorites indicates it is molten iron enriched with sulfur. Seismic readings from NASA’s InSight probe on the surface show us Mars’ core is bigger and much less dense than previously believed. These things suggest the presence of additional lighter elements such as hydrogen. With this information, we prepare iron alloys that we expect to constitute the core and subject them to experiments.”

The experiment’s findings

The experiment incorporated diamonds, lasers, and an unanticipated shock. Yokoo made a sample of material having iron, sulfur, and hydrogen, Fe-S-H, which is what he and his team expected the core of Mars was once made from.

They fixed this sample between two diamonds and compressed it while heating it with an infrared laser. This was to imitate the approximated temperature and pressure at the core. Sample observations with X-ray and electron beams permitted the team to image what was taking place during melting under pressure and even map how the sample’s composition transformed during that time.

” We were astonished to see a specific behavior that could explain a lot. The originally homogeneous Fe-S-H separated into two unique liquids with a level of complexity that has not been seen before under these sort of pressures,” claimed Hirose. “One of the iron liquids was rich in hydrogen, the other rich in sulfur, and this is essential to discussing the birth and at some point death of the magnetic field around Mars.”

The liquid iron-rich in hydrogen and poor in sulfur, being less dense, would certainly have risen above the denser sulfur-rich, hydrogen-poor liquid iron, creating convection currents. These currents, comparable to those in the world, would have driven an electromagnetic field able to maintain hydrogen in an atmosphere around Mars, enabling water to exist as a liquid.

Unlike the Earth’s internal convection currents, which are very long-lasting, once both liquids had fully separated, there would certainly have been no more currents to drive an electromagnetic field. Furthermore, when that occurred, hydrogen in the atmosphere was expelled to space by the solar wind, resulting in the breakdown of water vapor and, ultimately, the evaporation of the Martian oceans. Moreover, this would all have happened around 4 billion years ago.

The future of this research

” With our outcomes in mind, more seismic research of Mars will hopefully verify the core is without a doubt in distinct layers as we estimate,” claimed Hirose. “If that holds, it would aid us to complete the story of how the rough planets, including Earth, formed and explain their composition. Moreover, you might feel that the Earth could eventually lose its magnetic field too. However, do not stress, that will not take place for at least a billion years.”

The Japan Society supported this work for the Promotion of Science (JSPS) KAKENHI (Grant No. 16H06285 and 21H04506).

Read the original article on Science Daily.

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