Page 24 - EngineerIt June 2021

SPACE SCIENCES

Yeven get a little disoriented by it, Using cell phones as
our smartphone may be able
to sense space weather and

according to Sten Odenwald of NASA’s
Space Science Education Consortium
at Goddard Space Flight Centre in space weather vanes
Maryland, in Space Weather, who
tested how geomagnetic storms affect
the magnetic sensors in cell phones. Tiny magnetometers have turned your phone
The new research suggests that apps
being developed to use cell phone into a compass, and new research shows they
magnetometers to pinpoint locations are sensitive to geomagnetic storms.
could be susceptible to space weather
errors. On the other hand, millions of By Larry O’Hanlon
phones sensing changes in Earth’s
magnetic field could potentially create
a vast observatory to help scientists
understand these geomagnetic storms. because his research took place during the recent 11-year solar minimum, when the Sun
Cell phone magnetometer chips are could not be counted on to provide very much in the way of sunspots and coronal mass
being explored as a backup for GPS, ejections that can create significant geomagnetic storms on Earth.
which uses satellite signals to triangulate In lieu of the Sun’s cooperation, Odenwald used magnetic data from the
location and thus is often inaccurate or powerful Halloween storms of 2003 and essentially ran the storms on the phones to see
unavailable in places where signals can’t whether their magnetic signals would rise above the level of background noise. He also
penetrate, such as inside large buildings simulated the storms more directly by putting the phones into controlled magnetic fields.
or underground. Odenwald found that smartphone magnetometers are capable of detecting the
“Smartphone magnetometers very small magnetic field changes that accompany the strongest geomagnetic storms,
are being commercially explored for especially at higher latitudes in North America, where magnetic field lines converge and
applications as diverse as locating dip earthward as they near the magnetic north pole. Under certain circumstances, he
customers in shopping malls for targeted concluded, geomagnetic storms could be a significant source of error in compass and
advertising, to precision needle-guided other positioning apps. But he also noted that the ubiquity of smartphones and their
surgery,” wrote Odenwald. magnetometers presents an unprecedented opportunity for studying global changes in the
But there’s a catch. Geomagnetic geomagnetic field during significant solar storm events. n
storms can buffet and temporarily alter
the shape of Earth’s magnetic field so
theoretically, they could degrade the
accuracy of magnetometer chips. This
degradation could be a problem if your
target advertising hits in the wrong place
or you’re performing needle-guided
surgery and miss the mark.
To find out whether phones are
susceptible to the vagaries of space
weather, Odenwald tested the iPhone
6S, Samsung Galaxy Note 5, Samsung
Galaxy S8, and Samsung Galaxy S9 in
simulated geomagnetic storms. Simulated
storms were needed, Odenwald said,

It is interesting to note that GPS
specifications allow a global
average user range error (URE)
of ≤7.8 m with 95% probability.
Actual performance exceeds the
specification. On May 11 2016, the

global average URE was ≤0.715 m
(2.3 ft.), 95% of the time. Magnetometers have turned cell phones into compasses, which are sensitive to
geomagnetic storms. Picture Credit: Larry O’Hanlon

EngineerIT | June 2021 | 22