Mars Disrupts Earth’s Climate and Ocean Currents Every 2.4 Million Years!

The influence of orbital parameters on Earth’s climate is well established. These are the famous Milankovitch cycles. However, other larger-scale astronomical interactions could also govern the establishment of warm periods. This is notably the case of the orbital resonance between Earth and Mars. A new study shows that this forcing, which occurs every 2.4 million years, could even influence deep ocean circulation.

Throughout its history, Earth has experienced numerous climate variations. Most of them show a cyclicality of about 10,000 to 100,000 years, which is linked to the evolution of certain orbital parameters, such as eccentricity (variation in the shape of Earth’s orbit), obliquity (variation in the tilt of the rotation axis), and precession of the equinoxes (variation in the orientation of the rotation axis). This astronomical forcing induces cyclical variations in insolation, which govern Earth’s climate. These are known as the Milankovitch cycles.

Earth’s climate influenced by Mars every 2.4 million years

However, sedimentary records indicate the existence of larger-scale paleoclimatic cycles. These would be linked not to variations in the astronomical parameters of the Earth-Moon system, but to large cycles involving other planets of the Solar System. Evidence of these cycles, spanning millions of years, is much rarer, and this forcing phenomenon is much less constrained than the Milankovitch cycles.

Several studies have already noted the existence of a 2.4-million-year cycle, which would be related to an interaction between the orbits of Earth and Mars. It appears that the orbits of the two planets regularly enter into resonance, affecting their eccentricity. Every 2.4 million years, Earth would thus find itself closer to the Sun, a situation that leads to a period of climate warming.

A new study by researchers from the University of Sydney and Sorbonne University reveals that this astronomical interaction between Mars and Earth could even have affected the deep ocean currents of our planet.

Mars regularly disrupts deep ocean currents through climate warming

Scientists analyzed the organization of sedimentary layers deposited in deep-sea environments over the last 70 million years. They identified 387 interruptions in sedimentation, indicating episodes of seafloor erosion and reorganization of deep-sea currents. These events occurred cyclically… approximately every 2.4 million years! Comparison with astronomical models reveals that this cyclicity is indeed associated with the orbital interactions between Mars and Earth.

These results, published in the journal Nature Communications, suggest that global warming induces an intensification of deep ocean circulation. If in the past these warm periods have been governed by Earth’s orbital parameters or interactions with other celestial bodies like Mars, the same link between climate and deep ocean currents can be assumed for the present and future, even if the causes of warming are different. These findings could help better understand how the ocean will respond to current climate warming.

Previously, models suggested that in the face of climate warming, the Atlantic current system (Amoc), which is responsible for the famous Gulf Stream, could weaken or even disappear. This new study proposes that this phenomenon could be counteracted by the development of new and powerful deep currents.

Is China about to retrieve Martian samples soon?

While NASA has been forced to slow down the development of the international sample return mission carried out in collaboration with ESA due to budget and schedule constraints, China, which also plans to bring back samples from the planet Mars to Earth with the Tianwen-3 mission, does not seem to be facing budget issues.

Although its mission, initially scheduled for a 2028 launch, has been postponed to the next launch window in early 2030, there are no indications suggesting that China will not meet its deadlines.

The Chinese mission’s architecture takes a simpler approach than that of NASA and ESA, although it is a very complex mission. Two Long March 5 launches will see the deployment of a landing and ascent vehicle, an orbiter, and a return module. On the Red Planet, the lander will use a robotic arm to collect surface samples, as well as a drill to collect material up to two meters below the surface. A six-wheeled robot or an Ingenuity-type helicopter could also be deployed to widen the range of collected samples. The goal is to bring back around 500 grams of Martian samples to Earth.

Selection of three potential sites

Recently, in the peer-reviewed scientific journal Journal of Geophysical Research, a Chinese article identified three potential sites for sample collection. These sites, located between 17 and 30 degrees north latitude, offer optimal sunlight and are at an altitude below 3,000 meters compared to the average Martian altitude, allowing the lander to benefit from a sufficient atmosphere to safely slow its descent.

Environments conducive to life and its preservation

Within these sites, landing ellipses of 50 kilometers by 20 have been identified to ensure a safe landing of the mission, avoiding rugged terrain, obstacles such as rocks, and steep slopes. Scientifically, these sites are known to host environments conducive to the emergence and preservation of life, such as sedimentary or hydrothermal systems, traces of past water activity, and geological diversity.

The final site selection announcement will be made later.

China wants to bring back Mars rocks well before NASA!

Article by Remy Decourt, published on 28/06/2022

As NASA and ESA prepare for a mission to bring back Martian samples in 2033, it is learned that China is advancing its Martian sample return mission to bring them back to Earth as early as 2031, two years before the American-European mission! A technological feat that would be seen as a blow to NASA and ESA.

As reported by Space News, Sun Zezhou, chief designer of the Tianwen-1 orbiter and Martian rover, presented a new architecture for the Martian sample return mission that China is preparing. Compared to the previous setup, the mission appears simpler with a single landing on Mars and no rover to retrieve samples from different sites, as currently done by Perseverance.

The return of Martian samples is considered one of the main scientific goals of robotic exploration. If China were to accomplish this before NASA and ESA, it would be seen as a difficult blow for the two Western agencies that hesitated for over 30 years before giving the green light to a Martian sample return mission. And if by chance, the Chinese invite Russia to participate in this MSR mission…

The European Space Agency (ESA) has decided that sending both the Fetch Rover and the Mars Ascent Vehicle together would be too complex and risky. Therefore, they have opted for two separate launches: one to send the Fetch Rover from ESA and another to land the rocket that will take off from Mars, near the rover. The orbiter that will bring back the samples to Earth is scheduled to be launched in 2027 and is expected to return to Earth in 2033.

China’s MSR mission, named Tianwen-3, consists of two parts and only two launches. The lander and Mars ascent vehicle will be launched together aboard the Long March 5 rocket; the orbiter and return module will travel to Mars on a Long March 3B rocket.

Previous missions have paved the way for China’s return of Martian samples. Tianwen-3 will utilize proven technologies related to Entry, Descent, and Landing (EDL), successfully demonstrated during the landing of the Zhurong rover on Mars in May 2021 (Tianwen 1 mission). Other mastered technologies include sample retrieval and orbital rendezvous, showcased during the Chang’e 5 mission in November and December 2020. After retrieving lunar samples, the probe took off from the Moon and completed an orbital rendezvous before transferring the samples to a capsule that brought them back to Earth.

According to Sun Zezhou’s presentation, Tianwen-3 is expected to land on Mars in September 2029. The landing site has likely not been chosen yet and is currently being selected. The mission is anticipated to land in the northern hemisphere during the autumn equinox. The orbital rendezvous around Mars to transfer the samples to the return module is planned for October 2030, with Earth return scheduled for July 2031.

Exciting times lie ahead in space exploration!

3.3 Billion Years Ago, Earth’s Primitive Landscape Was Already Shaken by Tectonic Seisms

In these old rocks in South Africa, researchers have identified the trace of the oldest known earthquake to date. 3.3 billion years ago, the coast of a paleocontinent would have been shaken by a powerful earthquake, generated at a subduction zone. These findings suggest that a modern plate tectonics did indeed exist in the Paleoarchean era.

At the southern tip of Africa lie fragments of some of the oldest crusts in the world. The Barberton Greenstone Belt indeed contains rocks over 3 billion years old. It is a rare relic of a crust formed when Earth was still very young. It consists of igneous and metasedimentary rocks associated with the formation of the first continents and also contains what appears to be remnants of very ancient oceanic crust dating back 3.3 billion years.

Studying this geological setting is a unique opportunity to go back in time and explore what the Earth’s landscape may have been like just 1 billion years after the planet’s formation. But by mapping the area precisely, two New Zealand researchers have discovered a strange formation.

Evidence of a Submarine Landslide 3.3 Billion Years Ago

On the sedimentary rocks deposited at great depth on the basement of this ancient ocean, researchers have identified levels of rocks typical of shallow depths, even from a continental environment. How to explain this abnormal superposition involving a change in the deposition environment? Upon closer inspection, it turns out that this upper level is not organized at all. Rocks blocks of various origins are completely mixed together. This type of architecture indicates that these rocks were not deposited there on the ocean floor in a conventional way, but they were reworked and transported, perhaps over long distances, during a particular event.

For the researchers, there is no doubt that these are deposits associated with submarine landslides. These types of debris avalanches are commonly observed consequences when a powerful earthquake occurs along a continental margin, at a subduction zone. And the two researchers know something about it, as New Zealand regularly experiences this type of event.

Evidence of a Powerful Earthquake Produced at a Subduction Zone

When an oceanic plate slides under a continental plate, as is the case for example in New Zealand, the sudden movement of the plates generates powerful earthquakes that destabilize sediments deposited on the continental shelf, at shallow depths. The resulting blocks will then slide down to the depths and settle on the oceanic crust, at the subduction front.

A scenario that apparently occurred 3.3 billion years ago. If this is the case, the Barberton Greenstone Belt could thus contain the oldest evidence of an earthquake known to date.

These findings, published in the journal Geology, suggest that 3.3 billion years ago, the primitive Earth was already animated by a plate tectonics similar to what we know today, including subduction zones involved in recycling oceanic crust and capable of generating powerful earthquakes. This study supports previous research results suggesting that plate tectonics, particularly the subduction process, have existed for 3.8 to 4.2 billion years!

This Star Unseen for 80 Years is About to Light Up the Night Sky

Astronomers are predicting the imminent occurrence of a rare phenomenon: a nova may soon appear in our sky in the coming months. A star that is currently inaccessible to us will then become easily visible to the naked eye.

In our sky, it sometimes happens that stars suddenly become very bright. This phenomenon lasts for a few days. Astronomers then classify the star in question as a nova. The name comes from a time when the star appeared new to the observers’ eyes. Researchers have been monitoring a system located about 3,000 light-years from our Earth that they suspect may soon offer us such an experience.

A White Dwarf and a Red Giant to Produce a Nova

The system in question consists of a red giant and a white dwarf, known as T Coronae Borealis (T CrB). Both are heavier than our Sun. The unstable red giant regularly ejects matter. The white dwarf, in turn, pulls this matter towards itself. This interaction is enough to trigger uncontrolled thermonuclear reactions that boost the system’s brightness (usually not more than what one would observe for a typical variable star). The system’s usual magnitude is around 10, indicating very low brightness, although in 2016, the brightness of T CrB nearly tripled – yet remained invisible to the naked eye.

It has happened before that the brightness of T Coronae Borealis increased thousands of times, making it visible to terrestrial observers. Once in 1866. Then in 1946. A quick calculation gives hope that a nova will appear again very soon, especially since astronomers report that before the 1946 event, the star had undergone a noticeable attenuation. They now note that it has just done the same.

A New Pole Star

Therefore, researchers believe that we should expect to be able to observe the nova between February and September of this year 2024. The magnitude of T Coronae Borealis would then drop to only 2. This would be an equivalent brightness to that of the Pole Star. All this will happen in the constellation known as the Northern Crown, a fairly easily identifiable small arc.

A Spider That Weaves Its Webs Underwater… To Breathe!

The diving bell spider is an exceptional weaver. A specialist in aquatic webs, it is capable of building a silk sheet underwater, anchored to vegetation, which allows it to breathe while submerged.

The diving bell spider (Argyroneta aquatica) is a spider species perfectly adapted to aquatic life, found throughout Europe and the Mediterranean. One of its most remarkable characteristics is its ability to build its web underwater.

A Life in a Silk-Woven Submarine

It all starts underwater, with the weaving of a bell-shaped web made of hydrophobic silk threads, firmly anchored to aquatic vegetation. The spider then surfaces to collect air bubbles using the hydrophobic silk covering its abdomen and legs, which it carries into its submerged web. Several trips are needed to build a bubble approximately one centimeter in diameter, forming a true air reservoir. Although the oxygen level in the bell balances with that dissolved in the surrounding water, regular renewal by the spider is ideal. Nevertheless, it is entirely capable of remaining submerged for up to four consecutive days, especially in winter, using only this reservoir to breathe. Despite its almost entirely aquatic life, the diving bell spider does not possess respiratory organs adapted to extracting oxygen dissolved in water.

When the Oxygen Bottle Turns Into a Cozy Nest

This same web has a particularly ingenious structure: woven between aquatic plant stems or rocks, it acts as a shield against predators. Thus, females protect their offspring by forming bubbles up to twice the size of those made by males, a characteristic potentially linked to the sexual dimorphism of this species. Egg laying occurs from spring to autumn: the male enters a female’s bubble for mating, and then the female lays a cocoon of about a hundred eggs. This cocoon is then placed in the bell, which has been enlarged and divided into two superimposed chambers: the cocoon occupies the upper chamber, while the female occupies the lower chamber. The egg incubation lasts about three weeks, and the young spiders that hatch have several options: some choose to stay nearby, while others escape by leaving the water and flying through the air using an ascending thread. Could the inventor of Spiderman have been inspired by these creatures?

Discover another spider that uses its web as a net to hunt… lizards! © Futura

The Start of Oceanic Crust Recycling Dates Back 3.5 Billion Years Ago

When was the first continent formed? How old is plate tectonics? These are major questions to understand Earth’s history, and their answers can be found in tiny and rare minerals. Zircons have enabled a team of researchers to propose that the beginning of oceanic crust recycling dates back 3.5 billion years ago.

By studying cratons, the oldest parts of continental crust, and especially with minerals like zircons, it is known that the first continents began forming over 4 billion years ago due to changes in magma composition. However, these initial continents were submerged and would only emerge around 3.3 billion years ago.

There is still uncertainty about when plate tectonics processes started, including the initiation of the first subduction zones. Subduction is one of the key drivers of tectonic plate movement. This constant evolution of how continents are arranged has significantly influenced the development of terrestrial life by affecting ocean currents and climate. Subduction also allows for the recycling of oceanic crust produced at oceanic ridges, providing hydrated minerals to the mantle and generating magmatism that helps in continent growth. Knowing when this cycle began is crucial for understanding Earth’s history.

While some observations suggest that subduction may have been active 4.2 or 3.8 billion years ago, these results are still debated as to whether it represents a primitive or modern form of the process.

A Subduction Process that Emerged 3.5 Billion Years Ago

Recent findings suggest that around 3.3 billion years ago, the situation was somewhat similar to today. This hypothesis is supported by a new study focusing on the evolution of oxidation state in granitic magmas over time, analyzed through zircons. The oxidation state of magmas forming continental crust is an indicator of how the mantle’s chemical composition has evolved, particularly due to oceanic crust recycling.

Data published in the journal Science Bulletin highlight a change around 3.5 billion years ago, indicating the initiation of a subduction process. Another change is observed around 2.6 billion years ago, marking the start of a 600-million-year cycle. The authors link this evolution to the burial of large sediment quantities into the mantle. This could be a response to continental landmass emergence (leading to a significant influx of eroded sediments into the marine realm) and the establishment of modern plate tectonics, with sediment productivity peaks related to continental masses coming together and the formation of early supercontinents. The subsequent cyclic pattern is associated with these supercontinents’ life cycles.

A Spectacular Image of the Remnants of a Star That Exploded Thousands of Years Ago!

Approximately 11,000 years ago, a massive star exploded in a supernova in the vicinity of Earth. Today, astronomers unveil a high-resolution image of what remains.

About 800 light-years away from Earth lies the remains of a massive star that exploded in a supernova around 11,000 years ago. Located in the Vela constellation, hence its name Vela. It is one of the closest supernova remnants to us and has been extensively photographed and studied. The Dark Energy Camera (DECam) mounted on a telescope at the Cerro Tololo Inter-American Observatory in Chile now provides one of the largest and most detailed images ever obtained.

A High-Definition Image Thanks to a Powerful Instrument

This image showcases the exceptional capabilities of the DECam, a telescope equipped with a four-meter diameter mirror, a nearly one-meter diameter corrective lens, and around sixty charge-coupled devices (CCD) acting as the “eyes” of the camera. The result is images of 570 megapixels each that can be superimposed, as done here, to obtain an image of Vela composed of nearly 1.3 gigapixels.

The image reveals blue and yellow filaments resulting from the compression of the interstellar medium by the hot gas violently ejected into space by the explosion of the massive star thousands of years ago. The supernova remnant now spans about 100 light-years, equivalent to 20 times the diameter of the full moon.

Exploring the Secrets of a Supernova Remnant

At the bottom left of the image of Vela, the pulsar born from the supernova explosion can be seen. It is an ultra-dense object with the mass of a star packed into a body just a few kilometers in diameter. The Vela pulsar still rotates very rapidly, sweeping the sky 11 times per second!

Astronomical Cycles and Climate Evolution in Earth’s History

The current climate change is a reality that cannot be denied. Numerous observations testify to a global warming trend. Glacier melting, decreasing polar ice caps, rising sea levels… these rapid changes observed over the past few decades are directly linked to human activities, which have been causing an unprecedented increase in greenhouse gas emissions into the atmosphere for over a century now.

Earth’s History Marked by Regular Climate Oscillation

Let’s set aside the current period for once and look at the long climatic history of Earth. And what a history it is! By studying sedimentary and glacial records, it becomes evident that the Earth’s climate has continuously varied over millions of years. The past is punctuated by major climatic events (both ice ages and warm periods), often associated with mass extinctions, overlaying a regular climate oscillation that alternates between glacial and interglacial periods following cycles of remarkable regularity ranging from tens to hundreds of thousands of years. These oscillations are particularly clear when examining the last 800,000 years for which we have detailed and precise data.

Cyclical Variations in Sunlight Influenced by Earth’s Movement in Space

Since the 19th century, scientists have been intrigued by this regularity and sought to identify its cause. Starting from the premise that the amount of sunlight, i.e., solar energy received by Earth, is the primary factor controlling temperature variations, scientists like Adhémar, Croll, and Milankovitch quickly identified the – or rather, the culprits. Such regularity can only be linked to variations in Earth’s orbital parameters that cyclically modify the amount of sunlight received. This astronomical forcing is experienced on a very short timescale: the alternation of seasons is tied to the fact that Earth is tilted on its axis of rotation, which alters the amount of sunlight received by the Northern and Southern Hemispheres during the year.

Notably, Milankovitch determined that three orbital parameters primarily control climate evolution over relatively short periods (geologically speaking) of tens of thousands of years. These parameters are the eccentricity of Earth’s orbit, the obliquity of its axis of rotation, and precession.

Eccentricity

Eccentricity seems to have the most influence. It signifies that Earth’s orbit is not a perfect circle around the Sun but rather an ellipse, whose shape is not stable over hundreds of thousands of years. The Earth’s orbit is influenced by other bodies in the Solar System or those that pass nearby. These planetary interactions gradually change Earth’s orbit from nearly circular to highly elongated. In the latter case, Earth ends up very close to the Sun annually.

Currently, Earth’s eccentricity is gradually decreasing, meaning the orbit is becoming more circular. However, the eccentricity variation is too small within human timescales to have a visible impact on climate. Its influence is only noticeable over much longer timescales.

Obliquity

As mentioned earlier, Earth’s axis of rotation is slightly tilted compared to the orbital plane. This tilt is what causes the seasonal changes. Similar to eccentricity, this tilt is not stable over time. There is a slight variation in the tilt angle, oscillating between 22.1 and 24.5 degrees. This variation occurs in cycles of 41,000 years and influences the intensity of seasons, which are more extreme in high latitudes (colder winters and hotter summers) when the tilt angle is strongest. Earth’s obliquity oscillation is also linked to gravitational interactions with other planets.

Currently, Earth’s axial tilt is 23.4 degrees relative to the “vertical” (in a frame of reference where the orbital plane is seen as the equator).

The Earth’s Climate: The Milankovitch Cycles and Human Influence

The Earth’s climate is influenced by various factors, including the Milankovitch cycles, which are astronomical variations in the Earth’s orbit and orientation. These cycles consist of changes in eccentricity, obliquity, and precession.

Eccentricity

Eccentricity refers to the shape of the Earth’s orbit around the Sun. It oscillates over a period of about 100,000 years from more circular to more elliptical. Currently, the Earth’s orbit is moderately elliptical, which affects the amount of solar radiation received by the planet. This variation plays a role in shaping the climate patterns on Earth.

Obliquity

Obliquity is the tilt of the Earth’s axis relative to its orbit around the Sun. It varies between 22.1 and 24.5 degrees over a cycle of about 41,000 years. Currently, the Earth’s obliquity is approximately 23.5 degrees (where 0 degrees represents a vertical axis and 90 degrees represents a horizontal axis). This angle is decreasing and will reach its minimum in about 10,000 years, leading to less pronounced seasons. A minimal obliquity promotes the formation and growth of polar ice caps, which in turn intensify climate cooling by reflecting solar energy. Conversely, a maximum obliquity favors deglaciation and global warming. This is a situation that Earth experienced 10,000 years ago.

Precession

Obliquity variation is not the only change that the Earth’s rotation axis undergoes. The gravitational influence of the Moon and the Sun, through tidal forces and the resulting deformation of the Earth, also perturbs the axis in another way. The Earth’s axis describes a small circle, like a spinning top about to stop. This oscillation, known as the precession of the axis, follows cycles of about 25,771 years. Again, this affects the seasons by either attenuating or enhancing the seasonal contrasts between the two hemispheres (North and South). Currently, the Southern Hemisphere is expected to experience stronger contrasts between summer and winter, while the seasonal differences should be less pronounced in the Northern Hemisphere. In 13,000 years, this situation is expected to reverse.

However, human activities have an impact on the climate as well.

Earth’s Climate: Milankovitch Cycles are not the Only Factor

Several cyclic patterns influence Earth’s climate, and it is their interactions that modulate the terrestrial climate on a large scale. The duration of each cycle depends on the relative position of the planets in the solar system and variations in their orbital parameters over time. From this perspective, the behavior of Earth and Mars appears rather chaotic, leading to significant variations in Milankovitch cycles over time, occasionally resulting in extreme climatic events, such as the Paleocene-Eocene Thermal Maximum 56 million years ago, as explained by Dutkiewicz and co-authors in a recent scientific publication.

Astronomical parameters are not the sole influencers of Earth’s climate, which responds to a multitude of factors and interactions that are not yet fully understood. Plate tectonics, through the rearrangement of continental masses, can influence Earth’s climate by controlling major ocean currents. These currents play a significant role in climate by affecting the moisture and temperature of the air and water. Factors such as the albedo effect of ice caps and chemical processes associated with soil weathering play a part in the carbon cycle, thus influencing the climate. All these factors tend to modulate the climate response to Milankovitch cycles and large astronomical cycles.

In a scenario without human presence, Earth would slowly move towards a new ice age, although this is not expected to occur for another 50,000 years.

However, with humanity’s presence, the situation is different.

Current Warming: What is the Impact of Milankovitch Cycles?

While some theories suggest that the current global warming could be due to astronomical forcing, most experts agree that this is not the case. The timescale is a crucial argument. The current warming is happening too rapidly to fit within the Milankovitch cycles, which operate over tens of thousands of years. Furthermore, there is evidence against warming being linked to increased solar radiation. Over the last 150 years, the amount of solar energy absorbed by Earth has remained relatively stable, with satellites even recording a decrease in radiation over recent decades.

On the other hand, the atmospheric CO₂ levels are at record highs. Natural fluctuations in CO₂ during past glacial cycles ranged between 180 ppm (parts per million) and 280 ppm. However, in just 150 years, CO₂ levels have risen from 280 to 421 ppm (2023 value). This increase is attributed to massive CO₂ emissions from fossil fuel combustion. The result is an enhanced greenhouse effect, leading to increased surface temperature and lower atmosphere temperature, despite the current astronomical forcing indicating cooling of the stratosphere.

Through human activities, mankind has effectively masked the natural climate signal linked to Milankovitch cycles. While astronomical forcing still plays a role, its impact is no longer discernible since the atmospheric CO₂ concentration exceeded 350 ppm, as indicated by NASA.