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Solar Flares and Their Effects
By Joan Whetzel
Solar flares are a part of life in our solar system, a function of the sun's life cycle. But what are solar flares? And how do they affect the earth as well as our satellites, the Space Station and the astronauts who work in space?
What Are Solar Flares?
Solar flares are described as enormous explosions that occur near sunspots on the sun's surface, lasting anywhere from a few minutes to as long as an hour.. They discharge with energy equivalent to a billion megatons of TNT. The energy released by solar flares takes on many forms - such as mass flows, proton and electron particle energy, and electromagnetic energy in the form of gamma rays and x-rays - which are monitored by NASA with satellite detection. The largest flares are X-class flares, followed by M-class flares which have 1/10 the power of X-class, and C-class coming in at 1/10 the strength of M-class flares.
Solar flares run a 3 phase life cycle. The first stage, the precursor stage, is set off by a release of magnetic energy which causes the discharge of mild x-ray emissions. In the second phase, known as the impulse stage, atomic particles (electrons and protons) accelerate to high energy, triggering harder x-ray and gamma ray emissions. During the third stage, the decay stage, the small x-rays gradually die away.
Effects on the Earth
The energy particles from solar flares contribute to an atmospheric phenomenon known as the aurora borealis in the northern hemisphere and the aurora australis in the southern hemisphere. Solar flares also impact Earth's space weather in another way, by producing highly energetic particle streams carried by solar winds. These events are called Coronal Mass Ejections (CMEs), which take only 8 minutes to reach Earth's atmosphere. When the CMEs strike Earth's magnetosphere, they introduce a radiation hazard to the International Space Station as well as any spacecraft, astronauts and satellites in the vicinity. In fact solar flares have been known to create massive electric power outages over extended time periods. In addition, if the Earth directly faces the solar flare as it explodes, the resulting bursts of energy can batter the atmosphere which alter how well the Earth is able to defend itself against space radiation.
Effects on Satellites and the International Space Station (ISS)
Solar flare emissions interrupt satellite and wireless communications including 2-way radios, mobile phones and mobile radios, radio broadcasts and GPS signals. These black-outs usually last only as long as the flare's radiation is still bombarding the Earth, after which the radio signals return but may continue to be affected for awhile afterward. The radiation emissions also affect orbiting satellites, increasing the drag on the satellites, and increasing the likelihood of changing the course of their orbit. The energy emitted by solar flares, in the form of large plasma ejections hitting the upper chromosphere, has been known to damage the electronics aboard spacecraft and satellites as well. This disrupts communications with receivers on Earth as well as communications between the Earth and the ISS, which could cause problems with routine and emergency transmissions but could also seriously delay flights to and from the space station.
Effects on Astronauts
The radiation from solar flares also poses risks to manned missions to the moon, mars and other planets. The proton emissions can go through the human body, which is harmful to living cells, which could prove hazardous to astronauts during travel to other planets as well as during extravehicular activities (EVAs, a.k.a. known as spacewalks) on the ISS. This is due to the lack of protection offered by the Earth's atmosphere, and are only protected by a thin layer of aluminum in most spacecrafts. Some form of magnetic shielding is usually required for the astronauts' protection. Solar flare activity is closely monitored, warning astronauts in plenty of time to move to areas in the spacecraft with better protection.
As the presence of humans and human technology in space increases, an awareness of the dangers presented by the solar system needs to be continually addressed. With the ISS construction, as well as other space construction projects not yet started, astronauts will need to spend large amounts of time outside the vehicle on construction and repairs. In the event of CMEs (solar flares) occurring during these EVAs, the astronauts could easily receive doses of radiation that exceed the dosage allowed in a one-year period. Any astronauts hit with this dosage would not be permitted back out in space for at least 1 year.
For Further Information on Solar Flares Check Out this Website:
The Space Weather Bureau