Massive solar storms in space can be picked up by iOS and Android smartphones, meaning billions of people have a personal geomagnetic storm detector — but the signals threaten to interfere with future location-based applications.
Hoping to get the public more involved in science, study author Sten F. Odenwald, an astronomer at the NASA Goddard Spaceflight Center, published a paper on the topic April 2 in Space Weather. It indicates that even through the unavoidable interference caused by other smartphone components, the phone's built-in magnetometers can detect geomagnetic storms.
"Smartphones — at least theoretically — should be able to detect some of the strongest storms, pretty easily in fact," Odenwald told The Academic Times. "Especially if you happen to live up in the northern latitudes — in Minnesota or in Canada, or places like that where it really rocks and rolls."
Magnetometers are devices that can detect magnetic field fluctuations. Tiny types of these sensors are placed in conventional smartphones to support the mechanics of the compass feature.
Not to be confused with a GPS system, a smartphone's internal compass helps to indicate the position of a person using it to navigate on a map while walking around. Additional examples of its utility are the "share my current location" and "find my" features on an iPhone.
However, these smartphone magnetometers have limitations.
"For the electronics in a smartphone, there are all kinds of things that make it a fairly noisy environment," Odenwald said. "The signal has to be strong enough to get above the digital noise."
"Yet," he continued, "You're still able to make measurements of the Earth's magnetic field."
This magnetic field is sometimes interrupted by geomagnetic storms. Such storms occur when the sun starts to eject plasma, which induces changes in the field, often manifesting as beautiful auroral displays, otherwise known as the northern lights.
Odenwald's work suggests that regular smartphones can pick up on that chaos in space. His first attempt to study the connection between smartphones and these geomagnetic storms took place in 2017, where he detected a few random storms during the fall. However, the results were inconclusive.
He recently tried another approach, keeping in mind that these storms only happen about once every few months.
"If you're not lucky enough to be monitoring with your smartphone when there's an actual storm going on, why not do the next best thing?" he asked. "Why not simulate one?"
After going through tons of solar storm records from a magnetic observatory's archive based in Fredericksburg, Virginia, Odenwald picked out a couple of options.
"I basically selected two really good typical storms, one strong one and one sort of middling level," he said. "And at three different latitudes: the mid latitudes where we are, latitudes up near the northern tier states and then latitudes comparable to where the aurora are seen very easily."
Then, he performed a series of measurements of a typical smartphone's magnetometer noise and added that to the storm signals. From there, the researcher observed the overlay of the noise and the signal to see if the latter could still be detected.
"I looked to see whether or not … you could actually see the wiggles from the actual storm event against the noise of the smartphone measuring process," he explained. "You get measurements of the actual thing, but seen through the noise of the smartphone."
The results of the study indicate that, particularly at northern latitudes, very strong solar storms can indeed be caught by a smartphone magnetometer.
Similar types of disruption in communication devices trace back to the mid-19th century. Odenwald relayed that telegraph systems were notoriously corrupted by geomagnetic storms, which produce large currents in the ground. When shortwave radio was later invented, solar flares affected those waves, too.
"Now we have smartphones," he said. "Sure enough, smartphones are affected by space weather events like geomagnetic storms."
A potential negative consequence of the phone-based magnetometers fluctuating along with the storms is that several upcoming applications appear to need a smartphone to have a properly functioning built-in compass feature.
According to Odenwald, one such application is a marketing tactic that would display pop-up advertisements for a specific store as a user passes it in a shopping mall. A more crucial implementation of the magnetometer's properties, he says, is a proposed medical program that would use it to position probes for brain surgery.
"If you happen to be doing that during one of these geomagnetic events, you're likely to pick up enhanced noise," Odenwald warned. "And instead of getting that tumor, you're going to get the person blind or give them a partial lobotomy."
On a lighter note, Odenwald proposes a more forward-thinking plan of action for these smartphone magnetometers.
"You could get citizen scientists to use their smartphones in [a] recording mode to record during a specific geomagnetic storm that's going on," he explained. "And then, when the storm is over, they send that data to a scientist."
Conceivably, that data could be put together to create a "movie" of what that geomagnetic storm's effect would look like on a global basis, Odenwald said. It would be like a dynamic map.
"It might be fun to see the actual disturbance kind of mapped out as a movie by crowdsourcing, basically," he added.
The study, "Can Smartphones Detect Geomagnetic Storms?," published April 2 in Space Weather, was authored by S. F. Odenwald, Goddard Space Flight Center.