12 September 2013
Love the Sun? It’s easy on a mildly warm spring day. Flowers are in bloom, and children play. The warm sunshine lightly caresses your face. However, if you’re an astronaut or it’s your job to protect the integrity of our electrical grid, you know there’s another side to the Sun: the Sun’s dark side. Well, not really dark. The Sun’s always light, but you get the idea.
In fact, it’s just when the Sun is at its very brightest — when it flares — that it’s most dangerous. Cheerful light-giver or flaring disrupter, the Sun’s disposition not only changes like the weather, the changes are called the “weather.” But the Sun’s weather is referred to as “space weather” because its powerful effects dominate the entire Solar System — the planets and the space in between.
The solar wind is the constant out-flowing of charged particles from the Sun into space. When this wind strikes the earth’s magnetic field, it produces auroras visible at the poles. At the North Pole, this aurora is known as the northern lights. But the Sun has more than “wind,” it also has its own version of lightning — solar flares.
Just when you thought it was safe to go back into space . . .
The Sun’s weather goes through eleven-year cycles marked by increases and decreases in the number of sunspots. These “spots” are slightly darker and cooler areas on the surface of the Sun, which are created by magnetic forces beneath the Sun’s surface. Sunspots are like caps trapping a lot of pent-up energy below the surface. Although the exact mechanics of solar flares is still a mystery, when the trapped energy reaches a certain level, it bursts out of the Sun in the form of a solar flare. Invisible from the surface of the earth, a solar flare’s signature is only detectible using telescopes operating outside the earth’s atmosphere — in space.
On the good side, these flares actually have little effect on those of us with the good sense to stay out of space. The earth’s atmosphere shields us from almost all the effects of solar flares. At their worst, X-class flares affect the earth’s upper atmosphere and can cause radio blackouts for short periods of time. But the earth’s atmosphere is no protection if you’re in space. So, if you’re an astronaut, gadding about in the heavens, these flares are big trouble.
With solar flares, the Sun ejects radiation powerful enough to pass through the outer shell of a spacecraft, a spacesuit, and the human being inside. In space, exposure to a solar flare is fatal. Again, the typical spacesuit and spacecraft provide no protection for the unlucky astronaut caught in the radiation from one of these flares.
So, how did our astronauts survive the missions to the Moon? With careful timing. Although the timing of any particular solar flare can’t be predicted, there are rather definite cycles of rest and activity. Our lunar missions were carefully timed to coincide with periods of low activity. Still, one of the greatest known, but least publicized, risks of a trip to the Moon was an unexpected solar flare.
Why so little publicity? I would guess that attention tends to focus on factors that human effort can influence or control. With solar flares, silent hope may be the most natural response to a possible event so firmly and completely in the hands of fate.
Novelist James A. Michener wrote “Space,” a fictionalized account of the history of the U.S. space program from the end of World War II through the Apollo landings on the Moon. The book ends with a fictional tragedy in which risky timing of a Moon mission results in the deaths of two astronauts from exposure to a solar flare.
Needless to say, this doesn’t bode well for those hoping to colonize the earth’s lifeless and barren satellite — the Moon. Of course, solar flares can be ducked and dodged. Colonists would have a bit of warning. We can detect solar flares as they leave the Sun. After detection, there would be about 8 minutes for colonists or astronauts to receive the warning and take substantial cover.
The perils of space travel aside, most of us can breathe a sigh of relief when it comes to solar flares. As long as we stay out of space, we’ll be ok. I don’t know about you, but I can handle a life without extensive space travel. And the Moon is not my idea of a garden spot for a vacation. So, I doubt I’ll ever be living there.
Unfortunately, the Sun ejects something worse than flares — something less like a wind, and more like an ocean tsunami. Coronal Mass Ejections, CME’s, are the worst of the worst. On the earth’s surface, we can avoid the flares, but not these waves. Still, a CME could come and go and, if you were asleep in your hammock, you might not even know it.
Sunspots are held in place by magnetic fields, which occasionally collapse, or break, releasing a blast of plasma from the Sun’s surface — a CME. These leave the Sun at about 7 million miles per hour. They are not infrequent, but the sun throws off CME’s in any and all directions. The earth is a small target. So, very, very few of the many CME’s strike the earth.
When a wave of highly charged particles does strike the earth, it extends the earth’s magnetic field stretching it farther and farther until the field snaps-back. This “snap-back” discharges an extremely large amount of electrical energy into the earth’s atmosphere. Then, the stretch and snap-back action is repeated — again and again. As the process continues, the earth’s atmosphere becomes saturated with electrical potential.
The highly charged atmosphere produced by a CME comes and goes far too quickly to affect human health. The same atmosphere that picks up the electrical charge, also, protects human beings from the directly harmful physical effects of CME’s. But without the protection of the earth’s atmosphere, astronauts and hypothetical lunar colonists would suffer swiftly fatal injuries from a CME — just as they would from a solar flare. Spacecraft shells and spacesuits offer as little protection from CME’s as they do from solar flares.
However, CME’s move more slowly. Our astronauts or lunar colonists could have between one and five days advance warning of a CME’s arrival. Like a jellyfish alert at the seashore, the warning could go up with some time to spare. Just as swimmers can stay out of the sea to avoid jellyfish stings, so astronauts or lunar colonists could take substantial shelter until the radiation from a CME subsided.
So, why are CME’s so much worse than solar flares? While CME’s are relatively harmless to human beings in the earth’s atmosphere, these waves can be the kiss of death to electrical transformers and sensitive electrical equipment.
Although high-magnitude CME’s are rare, these can create an intense electromagnetic charge in the earth’s atmosphere, which could damage sensitive electronic equipment. However, the greatest potential danger is to the electrical transformers and electrical transmission lines that form our electric power grid. In other words, without prompt defensive action, a powerful CME could potentially destroy our power grid or, at least, trigger prolonged blackouts.
Today, the potential dangers from CME’s are understood. With one to five days advance warning, serious damage to the equipment used to supply our electric power could easily be avoided by shutting down the entire grid. Not that such a shutdown wouldn’t be disruptive, but disruption is better than disaster.
Without a shutdown, the electrically charged atmosphere produced by a high-magnitude CME could induce a tremendous increase in the electrical load on power transformers and the entire power grid. With the power grid in North America operating at about capacity, a sudden and enormous increase in electrical load could cause power lines to sag or even snap. Transformers would blowout and massive blackouts would affect much of North America.
At the same time, a powerful CME would cause magnetic turbulence that would interfere with radio signals, electronic communications, and satellites causing temporary communication failures. GPS signals could be disrupted. Long metal structures, like pipes, could pick up and carry electrical currents with a variety of unintended and unfortunate results.
Without a prior shutdown, the damage could take a month or more to repair. Emergency services would have to operate with limited electric power and possibly damaged communication equipment. Cell phones or computers might not be directly affected, but the communication infrastructure, including cell relay towers and internet services, might be disabled making much of our communication technology useless.
However, before we become survivalists, stocking canned goods in our cellar in anticipation of the next CME, there is some good news to keep in mind. No expensive equipment or years of upgrading are necessary to protect our power grid — just a prompt and complete shutdown. Another piece of good news is that a high magnitude CME, one that could do the damage described above, only strikes the earth about once every 500 years.
Of course, some have suggested fantastically expensive and complicated accommodations to shield our ever-changing and growing electrical grid systems. However, most of these accommodations are less than necessary. With one to five days advanced warning, a complete shutdown is relatively simple to implement.
But what about exposed communication equipment such as satellites and our communication infrastructure — those electronics that can’t be shutdown? Some of these devices are of vital importance to emergency services. Here is where special shielding, though expensive, would do a great deal of good. Communication breakdowns can have extremely serious consequences, and a good portion of our communication infrastructure can’t be shutdown. Another substantial portion is composed of delicate electronics that could be damaged even when powered-down.
Again, the study of Greenland ice cores reveals that a super CME — ones that could cause the extensive damage — only strikes the earth about once in 500 years. However, the ice cores also reveal that smaller events, more disruptive than destructive, happen several times a century.
During the 20th Century, three significant CME’s struck the earth: One in 1921 and a second in 1960, which produced reports of widespread radio disruption. However, we can get the most contemporary picture of the effects of a CME from the third event, which significantly disrupted Quebec, Canada’s electrical power grid in March of 1989.
A CME left the Sun’s surface on March 6, 1989. Three and a half days later, on March 9, intense auroras formed at the poles and could be seen as far south as Texas and Florida — these were the first signs that a severe geomagnetic storm had struck the earth.
The CME caused short-wave radio interference. Signals from Radio Free Europe into Russia were disrupted. Suspicions that the Soviet government had jammed the signal triggered Cold War fears of an impending nuclear strike.
By midnight, communications from a weather satellite were interrupted. Another communication satellite, TDRS-1, recorded over 250 anomalies caused by the increased particles flowing into the satellite’s own electronics. The space shuttle Discovery, on a mission, experienced an unusually high reading from a pressure sensor on one of its fuel cells. The anomalous reading disappeared after the geomagnetic storm ended.
Quebec, Canada rests on a large layer of rock, which acted as shield against the natural discharge of the electricity from the highly charged atmosphere to the ground. Without discharge into the ground, the powerful atmospheric electrical potential found its path of least resistance along utility transmission lines. Circuit breakers on Hydro-Québec’s power grid were tripped, and Quebec’s James Bay network experienced a 9-hour power failure.
Today, geomagnetic storms and solar flares are monitored from the Solar and Heliospheric Observatory (SOHO) satellite, a joint project of NASA and the European Space Agency. Currently, standards are being developed for utilities including the required installation of protective equipment and the establishment of emergency procedures to deal with future CME’s. Also, special protocols are being developed for nuclear power facilities to assure core shutdowns in case of a high-magnitude CME event.
But once we know that odds of a big CME — one every 500 years — the next question is: How long has it been since the last “big one?”
The granddaddy of them all happened on September 1, 1859. The “Carrington Event,” began when an amateur astronomer, Richard Carrington, observed the Sun suddenly grow larger and brighter. What he couldn’t have known, at the time, was that the Sun’s size and brightness only appeared to change. A CME, in the form of a circular cloud was expanding out from the Sun. This “halo coronal mass ejection,” was so bright and emitted so much light that the Sun appeared to grow in both size and brightness. Carrington, also, couldn’t have known why the “halo” cloud appeared to be almost perfectly circular. That apparent shape indicated that the CME was headed right for the earth.
Electrical equipment was relatively rare in 1859, but telegraph pylons threw sparks. Some telegraph operators were shocked by their equipment even after disconnection from their power supply. Other telegraph operators reported sending and receiving signals without external power — the equipment powered only by the electricity in the atmosphere. Magnetic instruments, as simple as a compass, wouldn’t give consistent readings.
Auroras, like the northern lights, which are seldom visible beyond the arctic circle, could be seen in the tropics. The northern lights were so bright in the Rockies that the glow was mistaken for sunrise by gold miners, who got up and started breakfast. In the northeastern U.S., people could read newspapers in the middle of the night by the light of the aurora. The Baltimore American and Commercial Advertiser waxed lyrical reporting, “The light was greater than that of the Moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested.”
This happened 154 year ago. So, if it’s once every 500 years . . . . Well, we’re still on the right side of the odds.