“Although the South Atlantic Anomaly arises from processes inside Earth, it has effects that reach far beyond Earth’s surface. The region can be hazardous for low-Earth orbit satellites that travel through it. If a satellite is hit by a high-energy proton, it can short-circuit and cause an event called single event upset or SEU. This can cause the satellite’s function to glitch temporarily or can cause permanent damage if a key component is hit. In order to avoid losing instruments or an entire satellite, operators commonly shut down non-essential components as they pass through the SAA.”
The European Space Agency (ESA) weighed in earlier this year about the South Atlantic Anomaly (SAA) – the mysterious dent in Earth’s magnetic field over the South Atlantic that is being weakened to the point of splitting apart by the planet’s molten metal outer core churning around and shifting old tectonic plates on top of each other so that they block the outer core from forming the magnetic field. Now NASA decided it’s time to reveal its concern about the SAA and how it’s affected NASA’s moneymakers – satellites.
In a press release accompanying an explanatory video (watch it here), NASA scientists explain how the SAA is like “a pothole in space,” jarring satellites every time they pass over it, causing electronic glitches, short circuits and other physical damage. And no, they can’t just fly around it because the SAA is far too big and a detour would make the area of missed communications even larger.
“In addition to measuring the SAA’s magnetic field strength, NASA scientists have also studied the particle radiation in the region with the Solar, Anomalous, and Magnetospheric Particle Explorer, or SAMPEX – the first of NASA’s Small Explorer missions, launched in 1992 and providing observations until 2012.”
Even though the rip keeps getting bigger, NASA appears less concerned about what’s directly underneath it on the surface, so it seems to imply that the increased solar radiation is nothing to worry about … yet. It can still affect ships and planes passing through, but the worst part is that the anomaly is “slowly but steadily drifting in a northwesterly direction.” You don’t need Google maps (although you might want to use them while you still can) to figure out that ‘northwest’ is the direction of South and North America. However, the press release still refers to the South Atlantic Anomaly as a “dent” and focuses primarily on “Modeling a safer future for satellites” – where NASA and SpaceX make their money.
Cynical? Yes. The SAA is obviously more than a “pothole in space” to be getting this kind of attention.
Hunting dogs use more than their noses to find their way back to their owners hundreds or even thousands of feet away, researchers have found. Turns out, these four-legged navigators may sense Earth’s magnetic field and use it as a compass, scientists are now reporting.
This ability, called magnetoreception, is common in many animals, including some whale species, dolphins and sea turtles, among others. Now, a new study carried out in the Czech Republic and detailed in the journal eLife, suggests adding at least some hunting dogs to this list.
“This ‘sense’ is beyond our own human perception and it is, therefore, very hard to understand its meaning for animals,” study researcher Kateřina Benediktová, at Czech University of Life Sciences Prague, told Live Science. Benediktová is a graduate student in the lab of Hynek Burda, another study author.
This work builds on previous research by Benediktová and Burda, along with a team of scientists, who found that several breeds of dog preferred to poop with their body aligned along the magnetic north-south axis. The researchers speculated that behavior could help the dogs map their location relative to other spots, such as their starting point, they said in their study published in 2013 in the journal Frontiers in Zoology, as reported by Science magazine.
In the new study, Benediktová and her colleagues looked specifically at hunting dogs because this group of dogs has astonishing homing abilities that are not fully understood. They have been bred over generations to seek out game and if they don’t find any, they navigate back to their owners over long distances, often using novel routes back. How these dogs pinpoint their owner’s location in densely forested areas is perplexing.
Between September 2014 and December 2017, Benediktová’s team equipped 27 hunting dogs of 10 different breeds, including fox terriers and miniature dachshunds, with GPS trackers. These dogs were allowed to roam in forested areas away from buildings, roads and powerlines. Dogs ran individually and returned on their own. Trips took between 30 and 90 minutes. Owners hid close to the location where the dog was released. The GPS data, from a total of 622 excursions in 62 different locations in the Czech Republic, were then compiled and analyzed.
What researchers found was that the dogs mostly followed their own scent to take the same route back as they did on the outbound trek — a method called “tracking.” In 223 of the excursions, however, the dogs took a novel route back using a method referred to as “scouting.” The researchers looked more closely at the GPS data from these “scouting” treks to investigate how those dogs found their way back. A majority of the scouting dogs began their return with a short run along Earth‘s north-south axis. The researchers noticed that this “compass run” occurred regardless of the dog’s actual return direction.
“We propose that this [compass] run is instrumental for bringing the mental map into register with the magnetic compass and to establish the heading of the animal,” the researchers wrote in their paper.
Those scouting dogs also returned faster to their owners than the dogs using the tracking method, in which they just came back the same way they went out.
“We were absolutely excited “when we found an unexpected magnetic behavior in the dogs’ scouting return strategy,” Benediktová said. “Hunting dogs roam over large distances. A human would most probably get lost without a compass and a map if roaming over comparable distances in unfamiliar forested areas. In addition, after the north-south compass run, dogs were able to run more directly to the owner.”
Kathleen Cullen, a neuroscience professor at The John Hopkins University who was not involved in the research, said the findings are exciting, “Overall, I think that the authors’ unexpected discovery that hunting dogs will often perform a ‘compass run’ before returning home is exciting — these results will certainly motivate further exploration of how exactly the mammalian brain encodes magnetic cues and then uses this information to achieve accurate navigation.”
Cullen added, “It is also interesting “that these results build on previous findings showing that other animals, such as migratory birds, also sense the Earth’s magnetic field to navigate back to their homes.”
When asked what motivated this study, Benediktová said that “the connection between navigation, homing and magnetoreception could be very close.” In addition, “its role in the orientation of dogs has not been studied as thoroughly as in migratory birds, turtles or subterranean mole rats.”
The researchers also tried to rule out other explanations besides the compass run for how the dogs found their way back to their owners. GPS data from scouting dogs showed no significant performance difference between dogs of different sexes, and dogs navigated back equally well in both familiar and unfamiliar terrain. They also determined that the position of the sun had little influence on the dog’s navigation ability, because most days were overcast. Dogs probably weren’t using distant landmarks to navigate because researchers saw no significant difference in homing abilities of tall and short dogs even though short dogs would be less able to see through the dense foliage. And the team ruled out the possibility of dogs using scent to navigate home because only 10% of the runs had winds blowing in the direction from owner to dog and scouting runs were nearly 100 feet (30 meters) from outbound runs.
In WWI, dogs delivered messages while under fire and they helped locate wounded soldiers and carried first aid kits to be used in the field. The amazing abilities have long been a source of amazement and curiosity. For every generation, there is a heartwarming movie like “Lassie Come Home,” about a dog who can travel long distances. This current Czech study may provide a clue to dogs’ phenomenal abilities.
“The magnetic field,” the researchers wrote in their paper, “may provide dogs with a ‘universal’ reference frame, which is essential for long-distance navigation, and arguably, the most important component that is ‘missing’ from our current understanding of mammalian special behavior and cognition.”
Cullen cautioned that the study needs to be replicated to make a stronger case for the conclusions, but if it is verified, the findings “suggest that a neural strategy in which magnetoreception contributes to the brain’s ‘internal GPS’ is likely to be more common than previously thought.”
A new study published in Nature Communications shows that previous changes in the direction of Earth’s magnetic field reached rates that are up to 10 times larger than the fastest currently reported variations of up to one degree per year. The authors combined computer simulations of the field generation process with a recently published reconstruction of time variations in Earth’s magnetic field spanning the last 100 000 years.
Study authors, Dr. Chris Davies from the University of Leeds – School of Earth and Environment and Catherine Constable from the Scripps Institution of Oceanography, UC San Diego, in California, demonstrate that these rapid changes are associated with local weakening of the magnetic field.
This means these changes have generally occurred around times when the field has reversed polarity or during geomagnetic excursions when the dipole axis — corresponding to field lines that emerge from one magnetic pole and converge at the other — moves far from the locations of the North and South geographic poles.
The clearest example of this in their study is a sharp change in the geomagnetic field direction of roughly 2.5 degrees per year 39 000 years ago. This shift was associated with locally weak field strength, in a confined spatial region just off the west coast of Central America, and followed the global Laschamp excursion – a short reversal of the Earth’s magnetic field roughly 41 000 years ago.
Similar events are identified in computer simulations of the field which can reveal many more details of their physical origin than the limited paleomagnetic reconstruction.
This detailed analysis indicates that the fastest directional changes are associated with the movement of reversed flux patches across the surface of the liquid core. These patches are more prevalent at lower latitudes, suggesting that future searches for rapid changes in direction should focus on these areas.
“We have very incomplete knowledge of our magnetic field prior to 400 years ago. Since these rapid changes represent some of the more extreme behavior of the liquid core they could give important information about the behavior of Earth’s deep interior,” Dr. Davies said.
“Understanding whether computer simulations of the magnetic field accurately reflect the physical behavior of the geomagnetic field as inferred from geological records can be very challenging,” Professor Constable said.
“But in this case, we have been able to show excellent agreement in both the rates of change and general location of the most extreme events across a range of computer simulations.”
“Further study of the evolving dynamics in these simulations offers a useful strategy for documenting how such rapid changes occur and whether they are also found during times of stable magnetic polarity like what we are experiencing today.”
All images courtesy Christopher J. Davies & Catherine G. Constable, Nature Communications
Reference:
“Rapid geomagnetic changes inferred from Earth observations and numerical simulations” – Christopher J. Davies & Catherine G. Constable – July 6, 2020 – Nature Communications volume 11, Article number: 3371 (2020) – DOI: 10.1038/s41467-020-16888-0 – OPEN ACCESS
Abstract
Extreme variations in the direction of Earth’s magnetic field contain important information regarding the operation of the geodynamo. Paleomagnetic studies have reported rapid directional changes reaching 1° yr−1, although the observations are controversial and their relation to physical processes in Earth’s core unknown. Here we show excellent agreement between amplitudes and latitude ranges of extreme directional changes in a suite of geodynamo simulations and a recent observational field model spanning the past 100 kyrs. Remarkably, maximum rates of directional change reach ~10° yr−1, typically during times of decreasing field strength, almost 100 times faster than current changes. Detailed analysis of the simulations and a simple analogue model indicate that extreme directional changes are associated with movement of reversed flux across the core surface. Our results demonstrate that such rapid variations are compatible with the physics of the dynamo process and suggest that future searches for rapid directional changes should focus on low latitudes.
Featured image credit: Christopher J. Davies & Catherine G. Constable, Nature Communications
Over the past 200 years, Earth’s magnetic field has lost around 9% of its strength. Meanwhile, a large region of reduced magnetic intensity has developed between Africa and South America — known as South Atlantic Anomaly. Over the past 5 years, however, a second center of minimum intensity has emerged southwest of Africa, suggesting that the South Atlantic Anomaly could split up into two separate cells.
Earth’s magnetic field is vital to life on our planet– it is a complex and dynamic force that protects living beings from cosmic radiation and charged particles from the Sun.
The current prevailing understanding is that it’s largely generated by a sea of superheated, swirling liquid iron that makes up Earth’s outer core around 3 000 km (1 864 miles) below the surface. It acts as a spinning conductor, producing electrical currents that generate the continuously changing electromagnetic field.
Image credit: World Data Center for Geomagnetism/Kyoto University
Image credit: World Data Center for Geomagnetism/Kyoto University
For the past 200 years, the magnetic field has lost about 9 percent of its strength on a worldwide average.
Meanwhile, a large region of reduced magnetic intensity has developed between Africa and South America — known as the South Atlantic Anomaly.
The South Atlantic Anomaly refers to an area where our protective shield is weak. This animation shows the magnetic field strength at Earth’s surface from 2014-2020 based on data collected by the Swarm satellite constellation. Credit: ESA
The minimum field strength in this area has pummeled from 24 000 nanoteslas to 22 000 from 1970 to 2020. At the same time, the area of the anomaly has expanded and advanced westward at a pace of around 20 km (12 miles) per year.
In addition, for the past five years, a second center of minimum intensify has appeared southwest of Africa, indicating that the South Atlantic Anomaly could rupture into two separate cells.
The magnetic field is commonly pictured as a powerful dipolar bar magnet at the planet’s core, tilted at about 11° to the axis of rotation. However, the growth of the anomaly signifies that the process involved in generating the field is more complex as simple dipolar models were not capable of accounting for the latest development of the second minimum.
The South Atlantic Anomaly refers to an area where our protective shield is weak. White dots on the map indicate individual events when Swarm instruments registered the impact of radiation from April 2014 to August 2019. The background is the magnetic field strength at the satellite altitude of 450 km (280 miles). Credit: ESA
Scientists from the Swarm Data, Innovation, and Science Cluster (DISC) used information from ESA’s Swarm satellite constellation to study the anomaly and have a better understanding of it. Swarm satellites are built to determine and accurately measure the different magnetic signals comprising the Earth’s magnetic field.
“The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously,” said Jurgen Matzka from the German Research Center for Geosciences.
“We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth’s core driving these changes.”
Image credit: ESA/ATG Medialab
Scientists have been speculating whether the present weakening of the field is an indication that the planet is heading for an imminent pole reversal, in which the north and south magnetic poles reverse places.
Such events have happened many times throughout the Earth’s history, and we are long overdue by the average rate — roughly every 250 000 years at which the switch occurs.
While the mysterious origin of South Atlantic Anomaly is yet to be identified, ESA said that at the surface level it does not present a cause for alarm. However, satellites and other spacecraft flying through the area are more likely to experience technical malfunctions as the magnetic field is weaker in this region, so charged particles can penetrate the altitudes of low-Earth orbit satellites. In addition, SWARM scientists think the intensity dip in the South Atlantic occurring now is well within what is considered normal levels of fluctuations.
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A NASA-sponsored researcher at the University of Iowa has developed a way for spacecraft to hunt down hidden magnetic portals in the vicinity of Earth. These gateways link the magnetic field of our planet to that of the sun, setting the stage for stormy space weather. The Magnetospheric Multiscale (MMS) mission will study these portals. Credit: Science@NASA
A favorite theme of science fiction is “the portal”–an extraordinary opening in space or time that connects travelers to distant realms. A good portal is a shortcut, a guide, a door into the unknown. If only they actually existed….
It turns out that they do, sort of, and a NASA-funded researcher at the University of Iowa has figured out how to find them.
“We call them X-points or electron diffusion regions,” explains plasma physicist Jack Scudder of the University of Iowa. “They’re places where the magnetic field of Earth connects to the magnetic field of the Sun, creating an uninterrupted path leading from our own planet to the sun’s atmosphere 93 million miles away.”
Observations by NASA’s THEMIS spacecraft and Europe’s Cluster probes suggest that these magnetic portals open and close dozens of times each day. They’re typically located a few tens of thousands of kilometers from Earth where the geomagnetic field meets the onrushing solar wind. Most portals are small and short-lived; others are yawning, vast, and sustained. Tons of energetic particles can flow through the openings, heating Earth’s upper atmosphere, sparking geomagnetic storms, and igniting bright polar auroras.
NASA is planning a mission called “MMS,” short for Magnetospheric Multiscale Mission, due to launch in 2014, to study the phenomenon. Bristling with energetic particle detectors and magnetic sensors, the four spacecraft of MMS will spread out in Earth’s magnetosphere and surround the portals to observe how they work.
Just one problem: Finding them. Magnetic portals are invisible, unstable, and elusive. They open and close without warning “and there are no signposts to guide us in,” notes Scudder.
Actually, there are signposts, and Scudder has found them.
Portals form via the process of magnetic reconnection. Mingling lines of magnetic force from the sun and Earth criss-cross and join to create the openings. “X-points” are where the criss-cross takes place. The sudden joining of magnetic fields can propel jets of charged particles from the X-point, creating an “electron diffusion region.”
To learn how to pinpoint these events, Scudder looked at data from a space probe that orbited Earth more than 10 years ago.
“In the late 1990s, NASA’s Polar spacecraft spent years in Earth’s magnetosphere,” explains Scudder, “and it encountered many X-points during its mission.”
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Data from NASA’s Polar spacecraft, circa 1998, provided crucial clues to finding magnetic X-points. Credit: NASA Because Polar carried sensors similar to those of MMS, Scudder decided to see how an X-point looked to Polar. “Using Polar data, we have found five simple combinations of magnetic field and energetic particle measurements that tell us when we’ve come across an X-point or an electron diffusion region. A single spacecraft, properly instrumented, can make these measurements.”
This means that single member of the MMS constellation using the diagnostics can find a portal and alert other members of the constellation. Mission planners long thought that MMS might have to spend a year or so learning to find portals before it could study them. Scudder’s work short cuts the process, allowing MMS to get to work without delay.
It’s a shortcut worthy of the best portals of fiction, only this time the portals are real. And with the new “signposts” we know how to find them.
X-FLARE: Earth-orbiting satellites have detected an X2-class solar flare from sunspot 1283. The explosion, which occured at 2220 UT on Sept. 6th, appears to have hurled a CME toward Earth. This is the second time today that sunspot 1283 has propelled a plasma cloud in our general direction (see also “Earth-directed Flare,” below). Stay tuned for estimates of their arrival times.
EARTH-DIRECTED FLARE: This morning at 0150 UT, sunspot 1283 produced an M5.3-class solar flare. NASA’s Solar Dynamics Observatory recorded the flash of extreme ultraviolet radiation:
Because of the sunspot’s central location on the solar disk, the eruption was Earth-directed–but is a CME heading our way? Around the time of the explosion, a number of plasma clouds were already billowing away from the sun, adding an element of confusion to the analysis. Tentatively, we expect Earth’s magnetic field to receive a glancing blow from a CME on Sept. 8th or 9th.
In a press release accompanying an explanatory video (watch it here), NASA scientists explain how the SAA is like “a pothole in space,” jarring satellites every time they pass over it, causing electronic glitches, short circuits and other physical damage. And no, they can’t just fly around it because the SAA is far too big and a detour would make the area of missed communications even larger.
Even though the rip keeps getting bigger, NASA appears less concerned about what’s directly underneath it on the surface, so it seems to imply that the increased solar radiation is nothing to worry about … yet. It can still affect ships and planes passing through, but the worst part is that the anomaly is “slowly but steadily drifting in a northwesterly direction.” You don’t need Google maps (although you might want to use them while you still can) to figure out that ‘northwest’ is the direction of South and North America. However, the press release still refers to the South Atlantic Anomaly as a “dent” and focuses primarily on “Modeling a safer future for satellites” – where NASA and SpaceX make their money.
