When space weather hits and interacts with the Earth, geomagnetic storms occur. Electrons,
protons, and other particles are blasted into space as a result of fluctuations within the
sun. As space weather reaches Earth, it triggers
many complex processes that can cause a lot of problems for anything in orbit. Scientists
are working to better understand these risks and protect satellites from them.
The Sun emits a steady stream of charged particles into space. These particles are collectively
known as the solar wind. They also carry the magnetic field of the sun.
Sometimes, localized fluctuations in the Sun can send unusually strong bursts of particles
in a particular direction. A geomagnetic storm occurs if Earth gets hit
by the enhanced solar wind generated by one of these events.
Typically, geomagnetic storms are caused by coronal mass ejections, explosions of plasma
from the sun's surface, and solar wind escaping through coronal holes spots of low density
in the Sun's outer atmosphere. The speed at which the ejected plasma or solar
wind reaches Earth is an important factor - the faster the speed, the stronger the geomagnetic
storm. Solar wind normally travels at about 900,000 mph. However, strong solar events
can release winds five times faster than normal. The strongest geomagnetic storm ever recorded
was caused by a coronal mass ejection in September 1859.
In some extreme cases, the mass of particles set telegraph instruments on fire when they
hit the Earth and caused electrical surges in telegraph lines that shocked operators.
The damage caused by a geomagnetic storm of this magnitude on Earth today would be in
the neighborhood of $2 trillion. A lifeform unlucky enough to be directly exposed
to the solar wind or other radiation from the Sun would be in grave danger. Fortunately,
Earth's magnetic field offers a lot of protection to humanity.
The magnetosphere is the first thing solar wind hits as it approaches Earth. Plasma surrounds
the Earth's atmosphere, which is composed of electrons and ions.
The planet's magnetic field dominates the atmosphere. Solar wind transfers mass, energy,
and momentum into the magnetosphere when it hits it.
The magnetosphere can absorb most of the energy from the solar wind daily. While strong storms
can overload this system, they can also transfer excess energy to the upper layers of Earth's
atmosphere near the poles. Auroras are the result of this redirection
of energy to the poles, but they can also cause changes in the upper atmosphere that
can harm space assets. Geomagnetic storms are a threat to orbiting
satellites that serve people on the ground in different ways. Magnetospheric storms absorb
energy from the atmosphere, causing the atmosphere to heat up and expand upward.
It significantly increases the density of the thermosphere, the layer of the atmosphere
that stretches from about 50 miles to roughly 600 miles above the surface of the Earth. The
higher the density, the greater the drag, which is problematic for satellites.
In February, the demise of SpaceX satellites was directly caused by this situation.
Falcon 9 rockets drop off satellites into a low-altitude orbit, normally between 60
and 120 miles above the Earth's surface. Using their onboard engines, the satellites slowly
overcome the force of drag to reach their final altitude of approximately 350 miles.
As part of Elon Musk's Starlink internet project, SpaceX launched 49 satellites on February
4, 2022, many of which burned up in the atmosphere a few days later. It was a geomagnetic storm
caused by the Sun that caused this over US$50 million failure.
While still in very low-Earth orbit, Starlink's latest batch of satellites encountered a geomagnetic
storm. As a result, their engines were unable to overcome the significantly increased drag,
and the satellites began falling toward Earth and eventually burning up in the atmosphere.
As a result of space weather, space-based assets are at risk of drag. Due to the increase
in high-energy electrons within the magnetosphere during strong geomagnetic storms, more electrons
will penetrate shielding and accumulate within the electronics of a spacecraft.
In what is similar to a small lightning strike, this buildup of electrons can discharge and
damage electronics. Even during mild geomagnetic storms, penetrating
radiation or charged particles can affect the output signal from electronics. Spacecraft
electronics systems can be affected by this phenomenon in any part, and if the error occurs
in a critical part, the entire satellite can fail.
Despite the rarity of total failures, small errors are quite common and usually fixable.
Finally, geomagnetic storms can interfere with satellites' ability to communicate with
Earth using radio waves. Many technologies rely on radio waves, for example, GPS.
Since the atmosphere is always distorting radio waves, engineers correct this distortion
when constructing communication systems. However, during geomagnetic storms, changes
in the ionosphere - the charged equivalent of the thermosphere that spans roughly the
same altitude range, will affect how radio waves travel through it. During geomagnetic
storms, calibrations designed for a quiet atmosphere are incorrect.
It is difficult to lock onto GPS signals due to this, and it can throw off the positioning
by a few meters. Aviation, maritime, robotics, transportation, farming, military, and other
industries cannot tolerate GPS positioning errors of a few meters.
Autonomous driving systems will also require precise positioning. For much of the modern
world to function, satellites are critical, and protecting space assets from space weather
is an essential research area. Several of the risks can be minimized by shielding
electronics from radiation or developing more radiation-resistant materials. Nevertheless,
there is only a certain amount of shielding that can be done in the face of a powerful
geomagnetic storm. With accurate forecasts of storms, satellites
and other assets could be protected to a certain extent by shutting down-sensitive electronics
or repositioning satellites to be better protected. Despite improvements in modeling and forecasting
geomagnetic storms over the past few years, the projections are often incorrect.
After a coronal mass ejection, the National Oceanic and Atmospheric Administration had
warned that a geomagnetic storm was likely to occur the day before or the day of the
Starlink launch.