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Swarm Mission Reveals Insights into Earth’s Magma and Ocean Trends
A recent investigation utilizing data from the European Space Agency’s (ESA) Swarm mission indicates that the subtle magnetic signatures produced by Earth’s tidal movements may provide critical information on magma distribution beneath the ocean floor. Moreover, this data could enhance our understanding of long-term variations in global ocean temperatures and salinity levels.
The Swarm initiative consists of a trio of satellites tasked with comprehensively studying Earth’s geomagnetic field. This magnetic field, which extends from the planet’s interior into the cosmos, is primarily believed to be generated by a swirling ocean of liquid iron located in the outer core. Contributions to this field also arise from magnetized rocks in the Earth’s crust.
Contrary to common perceptions, the oceans play a role in magnetic phenomena as well. The salty seawater serves as a moderate electrical conductor; thus, as oceanic tides traverse through Earth’s magnetic field, they generate faint electric currents. These currents, in turn, produce minor magnetic signals that can be detected from space.
Advanced Measurements from Swarm
The Swarm satellites, orbiting at altitudes between 462 km and 511 km, have achieved unprecedented precision in measuring Earth’s magnetic field. This capability allows them to detect faint tidal signatures and differentiate them from other, stronger magnetic signals originating from the planet’s interior. According to Anja Strømme, ESA’s Swarm Mission Manager, “This study illustrates that Swarm can yield valuable data on the characteristics of our oceans’ entire water column.”
Additionally, the data acquired from Swarm holds promise for revealing magma distribution, which could enhance our understanding of geological events such as the significant Hunga-Tonga volcanic eruption in 2022.
The research on these tidal magnetic signatures was recognized on the front cover of the Philosophical Transactions of the Royal Society A, a prominent scientific journal. This work stemmed from collaboration between researchers at the University of Cologne and the Technical University of Denmark.
Longevity of the Swarm Mission
Launched in 2013 with an initial mission duration of four years, the Swarm project has now surpassed a decade of operation. Strømme emphasizes the advantages of extending mission lifespans: “Prolonging a mission allows for exploration of scientific questions not originally anticipated, provided that the quality of the scientific output remains high and resources allow.”
However, the mission is gradually reaching the end of its operational life due to orbital drag, which is slowly drawing the satellites closer to Earth. This reduction in altitude has actually improved the mission’s ability to detect subtle signals that would have been challenging to capture from higher orbits at its inception.
Optimal Detection Conditions
Swarm’s proficiency in capturing these faint oceanic signals was further enhanced by a relatively inactive period of solar activity around 2017. As noted by Alexander Grayver, lead author of the study from the University of Cologne, “These represent some of the smallest signals that the Swarm mission has detected thus far.”
The solar minimum, occurring within the Sun’s approximately 11-year cycle, is characterized by reduced solar activity. During these periods, the Sun emits less solar matter—including electromagnetic radiation and charged particles—resulting in less interference with space weather phenomena, such as auroras. This decrease in solar emissions allows geomagnetic signals from Earth to be more readily identifiable by Swarm’s advanced instruments.
Looking ahead, there is hope that the next solar minimum, anticipated after 2030, will coincide with Swarm’s continued operation—albeit at a lower altitude—providing ongoing insights into the deep ocean’s temperatures and salinity through the detection of these faint magnetic signatures.
Source
www.esa.int