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By European Space Agency
ESA’s Solar Orbiter spacecraft has provided crucial data to answer the decades-long question of where the energy comes from to heat and accelerate the solar wind. Working in tandem with NASA’s Parker Solar Probe, Solar Orbiter reveals that the energy needed to help power this outflow is coming from large fluctuations in the Sun’s magnetic field.
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By NASA
6 min read
Quantum Scale Sensors used to Measure Planetary Scale Magnetic Fields
Magnetic fields are everywhere in our solar system. They originate from the Sun, planets, and moons, and are carried throughout interplanetary space by solar wind. This is precisely why magnetometers—devices used to measure magnetic fields—are flown on almost all missions in space to benefit the Earth, Planetary, and Heliophysics science communities, and ultimately enrich knowledge for all humankind. These instruments can remotely probe the interior of a planetary body to provide insight into its internal composition, structure, dynamics, and even evolution based on the magnetic history frozen into the body’s crustal rock layers. Magnetometers can even discover hidden oceans within our solar system and help determine their salinity, thereby providing insight into the potential habitability of these icy worlds.
Left: The magnetic field of Jupiter provides insight into its interior composition, structure, dynamics, and even its evolutionary history. Right: Image of the first prototype 4H-SiC solid-state magnetometer sensor die (2mm by 2mm) developed by NASA-GRC. Each gold rectangle or square on the surface represents an individual sensor, the smallest being 10 microns by 10 microns. Fluxgates are the most widely used magnetometers for missions in space due to their proven performance and simplicity. However, the conventional size, weight, and power (SWaP) of fluxgate instruments can restrict them from being used on small platforms like CubeSats and sometimes limit the number of sensors that can be used on a spacecraft for inter-sensor calibration, redundancy, and spacecraft magnetic field removal. Traditionally, a long boom is used to distance the fluxgate magnetometers from the contaminate magnetic field generated by the spacecraft, itself, and at least two sensors are used to characterize the falloff of this field contribution so it can be removed from the measurements. Fluxgates also do not provide an absolute measurement, meaning that they need to be routinely calibrated in space through spacecraft rolls, which can be time and resource intensive.
An SMD-funded team at NASA’s Jet Propulsion Laboratory in Southern California has partnered with NASA’s Glenn Research Center in Cleveland, Ohio to prototype a new magnetometer called the silicon carbide (SiC) magnetometer, or SiCMag, that could change the way magnetic fields are measured in space. SiCMag uses a solid-state sensor made of a silicon carbide (SiC) semiconductor. Inside the SiC sensor are quantum centers—intentionally introduced defects or irregularities at an atomic scale—that give rise to a magnetoresistance signal that can be detected by monitoring changes in the sensor’s electrical current, which indicate changes in the strength and direction of the external magnetic field. This new technology has the potential to be incredibly sensitive, and due to its large bandgap (i.e., the energy required to free an electron from its bound state so it can participate in electrical conduction), is capable of operating in the wide range of temperature extremes and harsh radiation environments commonly encountered in space.
Team member David Spry of NASA Glenn indicates, “Not only is the SiC material great for magnetic field sensing, but here at NASA Glenn we’re further developing robust SiC electronics that operate in hot environments far beyond the upper temperature limitations of silicon electronics. These SiC-based technologies will someday enable long-duration robotic scientific exploration of the 460 °C Venus surface.”
SiCMag is also very small— the sensor area is only 0.1 x 0.1 mm and the compensation coils are smaller than a penny. Consequently, dozens of SiCMag sensors can easily be incorporated on a spacecraft to better remove the complex contaminate magnetic field generated by the spacecraft, reducing the need for a long boom to distance the sensors from the spacecraft, like implemented on most spacecraft, including Psyche (see figure below).
The magnetic field lines associated with the Psyche spacecraft, modeled from over 200 individual magnetic sources. Removing this magnetic field contribution from the measurements conventionally requires the use of two fluxgate sensors on a long boom. Incorporating 4 or more SiCMag sensors in such a scenario would significantly reduce the size of the boom required, or even remove the need for a boom completely. Image Credit: This image was adopted from https://science.nasa.gov/resource/magnetic-field-of-the-psyche-spacecraft/ SiCMag has several advantages when compared to fluxgates and other types of heritage magnetometers including those based on optically pumped atomic vapor. SiCMag is a simple instrument that doesn’t rely on optics or high-frequency components, which are sensitive to temperature variations. SiCMag’s low SWaP also allows for accommodation on small platforms such as CubeSats, enabling simultaneous spatial and temporal magnetic field measurements not possible with single large-scale spacecraft. This capability will enable planetary magnetic field mapping and space weather monitoring by constellations of CubeSats. Multiplatform measurements would also be very valuable on the surface of the Moon and Mars for crustal magnetic field mapping, composition identification, and magnetic history investigation of these bodies.
SiCMag has a true zero-field magnetic sensing ability (i.e., SiCMag can measure extremely weak magnetic fields), which is unattainable with most conventional atomic vapor magnetometers due to the requisite minimum magnetic field needed for the sensor to operate. And because the spin-carrying electrons in SiCMag are tied up in the quantum centers, they won’t escape the sensor, meaning they are well-suited for decades-long journeys to the ice-giants or to the edges of the heliosphere. This capability is also an advantage of SiCMag’s optical equivalent sibling, OPuS-MAGNM, an optically pumped solid state quantum magnetometer developed by Hannes Kraus and matured by Andreas Gottscholl of the JPL solid-state magnetometry group. SiCMag has the advantage of being extremely simple, while OPuS-MAGNM promises to have lower noise characteristics, but uses complex optical components.
According to Dr. Andreas Gottscholl, “SiCMag and OPuS-MAGNM are very similar, actually. Progress in one sensor system translates directly into benefits for the other. Therefore, enhancements in design and electronics advance both projects, effectively doubling the impact of our efforts while we are still flexible for different applications.”
SiCMag has the ability to self-calibrate due to its absolute sensing capability, which is a significant advantage in the remote space environment. SiCMag uses a spectroscopic calibration technique that atomic vapor magnetometers also leverage called magnetic resonance (in the case of SiCMag, the magnetic resonance is electrically detected) to measure the precession frequency of electrons associated with the quantum centers, which is directly related to the magnetic field in which the sensor is immersed. This relationship is a fundamental physical constant in nature that doesn’t change as a function of time or temperature, making the response ideal for calibration of the sensor’s measurements. “If we are successful in achieving the sought-out sensitivity improvement we anticipate using isotopically purer materials, SiC could change the way magnetometry is typically performed in space due to the instrument’s attractive SWaP, robustness, and self-calibration ability,” says JPL’s Dr. Corey Cochrane, principal investigator of the SiCMag technology.
The 3-axis 3D printed electromagnet – no larger than the size of a US penny – is used to modulate and maintain a region of zero magnetic field around our 0.1 mm x 0.1 mm 4H-SiC solid-state sensor. NASA has been funding this team’s solid-state quantum magnetometer sensor research through its PICASSO (Planetary Instrument Concepts for the Advancement of Solar System Observations) program since 2016. A variety of domestic partners from industry and academia also support this research, including NASA’s Glenn Research Center in Cleveland, Penn State University, University of Iowa, QuantCAD LLC, as well as international partners such as Japan’s Quantum Materials and Applications Research Center (QUARC) and Infineon Technologies.
The SiC magnetometer team leads from JPL and GRC (left: Dr. Hannes Kraus, middle: Dr. Phillip Neudeck, right: Dr. Corey Cochrane) at the last International Conference on Silicon Carbide and Related Materials (ICSCRM) where their research is presented annually. Acknowledgment: The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004) and the NASA Glenn Research Center.
Project Lead(s):
Dr. Corey Cochrane, Dr. Hannes Kraus, Jet Propulsion Laboratory/California Institute of Technology
Dr. Phil Neudeck, David Spry, NASA Glenn Research Center
Sponsoring Organization(s):
Science Mission Directorate PICASSO, JPL R&D fund
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Last Updated Aug 06, 2024 Related Terms
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By USH
The concept that CO2 and climate change are political fabrications is often propagated by those who believe powerful entities are behind the so-called global warming hoax, aiming to convince the public that human activities are to blame. However, it is argued that climate change is a natural process, similar to events that have occurred throughout history. The video below by Suspicious0bservers provides a detailed analysis of the actual causes of current planetary changes and offers insights into what we might expect in the coming years.
The most recent complete magnetic pole reversal, known as the Brunhes-Matuyama reversal, occurred approximately 780,000 years ago. During this event, Earth's magnetic poles switched places. These reversals are part of Earth's natural geomagnetic processes and occur irregularly over geological timescales.
However, there have been shorter, less complete shifts called geomagnetic excursions. One of the notable recent geomagnetic excursions is the Laschamp event, which occurred about 41,000 years ago. During this event, the magnetic field weakened significantly, and the poles nearly reversed before returning to their original configuration.
Now, Earth is currently undergoing a cyclical magnetic pole shift, known as a geomagnetic excursion. This movement has been accelerating in recent decades, particularly with the North Magnetic Pole rapid movement from the Canadian Arctic towards Russia, which poses a significant extinction threat to many species.
The weakening of Earth's magnetic field and the shifting of its magnetic poles are well-documented phenomena.
In 2000, NASA and geophysicists reported a 10% decline in the magnetic field's strength. By 2010, the European Space Agency's Magnetic Mission updated this figure to a 15% loss, noting an acceleration from a 5% loss per century to 5% per decade. By 2020, another 5% decline was recorded, and the 2023 interpolated value showed further acceleration. The initial 10% reduction took 150 years, but the next 10% occurred within just 20 years. If this acceleration continues, we could lose 5% of the magnetic field every five years.
We anticipate a 50% reduction in the magnetic field by the early 2030s, a level that could make our technological lifestyle unsustainable and lead to severe weather impacts. Around 2040, a full magnetic pole flip or geomagnetic excursion is expected, although this could occur a few years earlier or later.
A critical concern in the coming years is the loss of ozone due to particle-driven molecular destruction, coupled with increased exposure to cosmic ray space radiation. This scenario would result in climate chaos and heightened radiation exposure. The only defense against these effects is Earth's magnetic field, which is currently weakening due to the ongoing pole shift.
Recent studies consistently show that magnetic reversals and pole shifts are extreme environmental events that significantly impact the biosphere. The primary drivers of these impacts are increased radiation and ozone depletion. Numerous studies confirm that solar protons, electrons, and cosmic rays are penetrating the atmosphere more effectively due to the weakening magnetic field, reaching critical levels.
This increased radiation has two main effects: ozone destruction allows more ultraviolet (UV) light into Earth's system, raising temperatures, and cosmic rays intensify extreme weather events, including heatwaves, cold snaps, storms, flooding, and droughts.
These changes not only affect the climate but also harm living organisms. Extra UV light is dangerous for animals, plants, and microorganisms, including oceanic plankton and chlorophyll-based food chains. Cosmic rays similarly amplify particle radiation's detrimental effects, causing cancer, cellular dysfunction, and DNA mutations.
Scientists clearly recognize that cyclical magnetic pole shifts pose significant challenges to life on Earth. Humans will face these challenges both directly and through their impact on the food chain.
Moreover, our dependence on electricity makes us particularly vulnerable. A weakened magnetic field could allow solar activity to disrupt power grids, resulting in widespread loss of heat, water treatment, food transport, communication, and critical infrastructure.
This growing issue highlights the planet's increasing vulnerability as it loses its protective magnetic shield.
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By European Space Agency
Video: 00:42:00 ESA’s Solar Orbiter may have taken another step towards solving the eighty-year-old mystery of why the Sun’s outer atmosphere is so hot.
On 3 March 2022, just a few months into Solar Orbiter’s nominal mission, the spacecraft’s Extreme Ultraviolet Imager (EUI) returned data showing for the first time that a magnetic phenomenon called reconnection was taking place persistently on tiny scales.
At that time, the spacecraft was about halfway between the Earth and the Sun. This enabled coordinated observations with NASA’s Solar Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph (IRIS) missions. The data from the three missions was then combined during the analysis.
Magnetic reconnection occurs when a magnetic field changes itself into a more stable configuration. It is a fundamental energy release mechanism in superheated gasses known as plasmas and is believed to be the major mechanism for powering large-scale solar eruptions. This makes it the direct cause of space weather, and a prime candidate for the mysterious heating of the Sun’s outer atmosphere.
It has been known since the 1940s that the Sun’s outer atmosphere, called the corona, is much hotter than the Sun’s surface. While the surface glows at around 5 500°C, the corona is a rarified gas of around 2 million °C. How the Sun injects energy into its atmosphere to heat it to this tremendous temperature has been a major puzzle ever since.
In the past, magnetic reconnection has usually been seen during large-scale, explosive phenomena. However, the new result presents ultra-high-resolution observations of persistent small-scale (around 390 km across) reconnection in the corona. These are revealed to be a long-lived ‘gentle’ sequence compared to sudden explosive releases of energy that reconnection is usually associated with.
The 3 March 2022 event took place over the period of one hour. The temperatures around the point of the magnetic field where the magnetic field intensity drops to zero, known as the null-point, sustained itself at around 10 million °C, and generated an outflow of material that came in the form of discrete ‘blobs’ travelling away from the null point with a speed of around 80 km/s.
In addition to this continuous outflow, an explosive episode also took place around this null point, and lasted for four minutes.
Solar Orbiter’s results suggest that magnetic reconnection, at scales that were previously too small to be resolved, proceeds continually in both gentle and explosive ways. This is importantly because it means that reconnection can therefore persistently transfer mass and energy to the overlying corona, contributing to heating it.
These observations also suggest that even smaller and more frequent magnetic reconnections await discovery. The goal is now to observe these with EUI at even higher spatio-temporal resolution in the future around Solar Orbiter’s closest approaches to estimate what fraction of the corona’s heat may be transferred in this way.
Solar Orbiter’s most recent closest passage to the Sun took place on 10 April 2023. At that time, the spacecraft was just 29 percent the Earth’s distance from the Sun.
Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA.
These results are published in Nature Communications in a paper titled Ultra-high-resolution Observations of Persistent Null-point Reconnection in the Solar Corona. Principal author Prof. Xin Cheng, Nanjing University, China, and Max Planck Institute for Solar System Research, Göttingen, Germany led an international team of 24 collaborators.
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By European Space Agency
Despite being essential to life on Earth, the magnetic field isn’t something we can actually see in itself, or ever hear. But, remarkably, scientists at the Technical University of Denmark have taken magnetic signals measured by ESA’s Swarm satellite mission and converted them into sound – and for something that protects us, the result is pretty scary.
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