From satellites malfunctioning to strange flashing lights seen by
astronauts on the International Space Station
there's something odd happening in certain parts of space close to Earth
and the cause of these effects could have wide-ranging impacts on all of us
in the future. In February 2016 the state-of-the-art Japanese x-ray
Observatory Hitomi launched atop of Mitsubishi rocket into a circular orbit
570 km above Earth its mission was to study high-energy
processes like black holes and supernovae in clusters of distant
galaxies but after just a month of successful operations the Japanese space
agency JAXA announced that on the 26th of March they had suddenly lost
communications with Hitomi, worse the satellite was in an uncontrollable spin,
attempts by the internal guidance system to correct the rotation only made the
problem worse, turning it faster and faster until the
solar panels broke away leaving Hitomi without power. On the 28th of April 2016
after a month of attempts to try and re-establish communications JAXA
declared the $273 million dollar Space Observatory lost but what was the cause
of Hitomi's demise. The answer lies in the peculiar pattern of radiation which
surrounds the earth discovered in 1958 by the first US satellite. The American
physicist James Van Alen proposed fitting Explorer 1 with a Geiger
counter attached to a small tape recorder to measure radiation levels
above the atmosphere. Sure enough Explorer 1 observed
distinct patterns of radiation during its 111 day mission these became known
as the Van Allen belts donut-shaped fields of energized particles emitted
from a Sun and trapped by the Earth's magnetic field.
In fact the radiation belts were discovered by Sputnik 2 just over two
months before the American Explorer 1, however due to sputnik's trajectory over
foreign territory and the secrecy around the mission, it meant that when the
signals were picked up by the Australians
the two sides refused to talk to each other and the Australians refused to
pass the data on. When the Soviets finally got their hands on the data they
mistakenly thought that the spikes in the radiation were a result of a recent
solar flare and by the time they figured out the real reason, the American Van
Allen team had announced the discovery. There are two main concentrations of
radiation surrounding the earth an inner radiation belt made up of mostly
energized protons that peaks at around 2,900 km and
an outer radiation belt mostly consisting of electrons of peaks at
around at altitude of 16,000 kilometers. The Van Allen belts are
responsible for Aurora's such as the northern and southern lights where they
meet the Earth's atmosphere around the magnetic poles and channel charged
particles into the upper atmosphere it's here that they react with atmospheric
gases and form the colorful displays. The most common Aurora color a pale
yellowish green is produced by oxygen molecules located about a 100 km
above the earth. Rare all red Aurora's are produced by high-altitude
oxygen at heights of up to 330 km and nitrogen produces blue or
purplish red Aurora's. But orbital surveys revealed another large area
where strong radiation dips down to just 200 kilometers above the Earth's surface
over a continent-sized area above the Atlantic coast of South America. This is
known as the South Atlantic anomaly or the cosmic Bermuda Triangle and it's
this that is the cause of a strange effects on both the human body and
robotic spacecraft. In the 1960s and 70s spacecraft in orbit relied upon early
computer chips which had much larger transistor sizes and were less sensitive
to the bombardment of charged particles this electronic toughness was especially
important for the Apollo missions which had to cross the Van Allen belt and
leave for protection of Earth's magnetic field. But during the missions the
astronauts reported seeing spots and streaks of light which
continue to flash even when they close their eyes. These visual effects are
called phosphenes and a 2006 survey of astronauts found at 47 out of 59
respondents had experienced them, some even reporting the lights had disturbed
their sleep.Although humans haven't crossed the Van Allen belts since
December 1972, all spacecraft that passed through the South Atlantic anomaly
experienced an increased dose of radiation of up to a thousand times the
usual levels for low Earth orbits. To deal with this the International Space
Station is fitted with shielding that protects astronauts from some of the
increased radiation when passing through the anomaly. Even so, the crew on the ISS
each wear personal dosimeters and electronic devices often suffer lock ups
or failures known as single event upsets these are more common with consumer
grade electronics like laptops which are brought with the crew which are built to
less demanding specifications than space or military-grade components which are
radiation hardened. Since the space shuttle missions, astronauts have
reported laptop failures over the South Atlantic,
fortunately the fix is usually a simple reboot. One way to shield against
high-energy charged particles is to use water good, yep, old-fashioned water makes an
excellent shield against ions electrons and protons due to its high hydrogen
content. Some astronauts have even taken to lining their sleeping areas with
water bags and even their dosimeters to reduce their total exposure number to
get longer and more frequent missions but of course at their own risk of
greater radiation exposure. However the Space Telescope's like
Hubble depend upon highly sensitive electronics to capture light from
distant galaxies. As Hubble passes through the South Atlantic anomaly
operators routinely switch off imaging sensors to avoid damaging them, however
one of Hubble's cameras the Wide Field Camera 3 can still function in this
portion of the orbit but the image is still register for characteristics
speckling of a radiation artifacts. Hitomi's light-gathering sensors were
ultimately found to be the cause of the failure cascade that led to the loss of
Japanese satellite. When passing through the South Atlantic anomaly the star
tracker which is used to orientate the craft with a known fixed point suffered
a series of glitches causing the satellite to switch to backup gyroscopic
instrumentation, which also then failed. Being on the opposite side to earth from
Japan and out of direct communication with Mission Control the error was only
discovered after it was too late. To avoid similar losses in future space
agencies are pursuing two strategies, first to better understand. The South
Atlantic anomaly itself and to make satellite electronics more resilient to
the effects of radiation as they pass through the danger zone. But the South
Atlantic anomaly is not a stationary phenomena, since 1958 scientists have
observed that the anomaly has been increasing in size and is also gradually
moving northward and westward this is in line with both the North and the South
Poles which are constantly moving around. Over the last 150 years the North Pole
has moved over a 1000 kilometers and has recently accelerated to 40 km
a year and the magnetic South Pole is now over a 1000 kilometers
away from a geographic South Pole. But there isn't just one anomaly either, in
fact there are many smaller ones scattered around the globe. The European
Space Agency is currently mapping these changes with the swarm mission which
launched three small satellites into polar orbits. Two of the swarm satellites
orbits side-by-side at an altitude of 450 kilometers and one orbits at a
higher altitude of 530 kilometers swarm has tracked fluctuations in the Earth's
magnetic field since 2014 and the data has revealed strange weather systems
deep beneath our feet that could be to blame for the spreading footprint of a
South Atlantic anomaly. Beneath 2,900 kilometers of crust
and mantel our planets core is in two parts, a central core of solid iron nickel alloy
about the size of a moon and at 4,500 degrees centigrade
that's as hot as the surface of an orange star like Arcturus and yet
solid due to the immense pressure of 50 million pounds per square inch bearing
down on it. The second outer core is molten and
about the size of Mars and fully envelops the inner core. As the planet
spins it's the movement of this molten metal outer core which is responsible
for the generation of a magnetic field. As the outer core is molten iron and is
a liquid it is affected by the Coriolis forces that come from a spinning earth
these forces create chaotic movement any outer core much like the weather in our
atmosphere and also like our weather, this outer core weather is driven by
hate but instead of heat from the Sun its heat from the inner core. This sets
up massive convection currents combined with the swirling effects of a Coriolis
forces it creates weather systems and storms
within the molten outer core. These storms create new temporary magnetic
poles that can be opposite to the surrounding area. This is what the South
Atlantic anomaly is, it's a pole reversal and as such it negates the effect of a
magnetic field around it, weakening it and allowing charged particles to come
much closer to Earth. Like atmospheric storms these outer core storms can also
merge and become larger which is how the South Atlantic anomaly is believed to
have grown in strength. The swarm mission also has identified a molten iron jet
stream within the outer core flowing westwards beneath Alaska and
Siberia a speed around 50 kilometers per year. Although this may not sound a lot,
this dense flow of iron takes a huge amount of energy to move and is
estimated to be hundreds of millions of years old. This increasingly chaotic
behavior in the outer core is thought to be the prelude to a complete
pole reversal something which has happened hundreds of times before in
Earth's history about every 250,000 years although the last time it happened
was over 750 thousand years ago so it looks like we are due for another pole
reversal any time. Although a pole reversal takes several thousand years to
complete during this time the Earth's magnetic field would weaken considerably
and might consist of multiple north and south poles spread anywhere around the
globe. A weaker magnetic field would bring
charged particles closer to the earth and could create ozone holes like that
which formed over the South Pole a few decades ago. This would increase the
level of ultraviolet light getting through and increase the risk of things like
skin cancer. It would also leave us more susceptible to solar storms which could
wreak havoc with the world's electrical power grid. By finding more weather
patterns in the core, swarm will help predict the future shape and behavior of
Earth's magnetic field but in any case building tougher satellites is said to
be big business in the coming decades as we see a surge in a number of small SATs.
By launching networks of miniaturized satellites into low-earth orbits,
governments and commercial satellite operators aim to replace heavy and
expensive geostationary satellites at a fraction of the cost. Small SATs usually
orbit below most of the radiation of the inner Van Allen belt and avoid the
long-term degradation of electrics found on geostationary satellites which
operate within the outer ventolin belt. However, small SATs have another problem
they frequently pass through the South Atlantic anomaly. One company working on
the problem is Thales Alenia space, a French-Italian aerospace company who are
Europe's largest satellite manufacturer. They are pioneering the use of gallium
nitride on silicon chips which operate at higher voltages and temperatures than
regular silicon chips, offering increased protection against radiation. In
commercial applications the loss of several nodes in a satellite network
would be an inconvenience, however if military satellite operators
transition from geostationary to low-earth orbits more stats then the
effects of the South Atlantic anomaly could introduce a significant
vulnerability especially after solar storms. Whichever
way we go what is happening deep beneath our feet is going to affect what happens
high above us and ultimately what happens here on earth so we need to take
steps to be prepared. So what's your thoughts about the growing instability
in the outer core and what do you think we should do to counter its possible
effects on our way of life let me know in the comments below. Don't forget you
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