Space Storms I. Introduction For years, citizens in the United States have had access to televised weather as well as radar images of storm activity from around the world. Weather prediction has become increasingly accurate with the advancement of technology and should continue to get better. For the majority of people following the weather has become a routine part of their lives. As a society we seem to be well educated about the weather occurring on our own planet but we know little of the weather that occurs in space. Space weather affects the earth in many different ways.
In less than a year scientists hope to be able to predict the weather in space like meteorologists do here on earth. A new spacecraft called IMAGE (which I will discuss later in detail), launched in 2000 and will carry many instruments that will paint a picture of space weather for scientists. Scientists will then be able to predict when space storms will hit. Most people don't even notice when a space storm is occurring but they are still affected. Space storms have the most severe effects on power grids, satellites, and astronauts. During space storms a strong current is created in the upper atmosphere called the auroral electrojet.
This is created from many electrons traveling at high speeds towards the earth as well as charged particles swirling around the earth and colliding with the upper atmosphere. This current can cause fluctuations in the geomagnetic field, which can cause electrical surges in power lines on the ground. An example is on March 13, 1989, an intense geomagnetic storm knocked out the Hydro-Quebec power grid and put large parts of Canada into darkness. Satellites are affected when particles strike the satellite and the craft's surface becomes charged. Sometimes this buildup can trigger a spark that will short-circuit the satellites electronics. Space storms also heat the earth's atmosphere which causes it to expand.
If the atmosphere expands far enough out it can enter the satellites orbit and drag it downward. This situation occurred in 1979 and caused the premature fall of Skylab. Astronauts are also at risk during severe space storms. During a storm the astronauts could be exposed to protons that could penetrate their spacesuits. Some storms may be powerful enough to penetrate the space station walls. NASA monitors space weather data to inform and protect their astronauts from any dangerous weather.
NASA will postpone or cancel any planned space walks and may order the astronauts to seek shelter in a shielded part of the space station if oncoming weather looks dangerous. Weather in space, similar to weather here on earth, is extremely variable. Conditions in space can go from being very calm to a severe storm in a matter of minutes. Space storms can last for hours or even days. Weather in space follows cycles similar to earth's weather that changes with the seasons. Solar magnetic activity is what causes solar flares and coronal mass ejections (CME), rises and falls every 11-years and geometric storms follow the same pattern.
This space cycle goes from solar-minimum to solar maximum every 11-years. Space weather is also somewhat affected by the suns 27-day rotation period that causes streams of fast and slow solar wind to sweep past the earth. Space weather, is created by different processes than the ones responsible for creating weather on earth. Terrestrial weather is created by dense, electrically neutral gas in the earth's lower atmosphere that is shaped by the laws of thermodynamics and fluid dynamics. Terrestrial weather also results from the sun's radiation as it heats the earth's oceans, landmasses, and atmosphere. In contrast, space weather consists mainly of plasma.
Plasma is a very sparse gas that consists of an equal number of positively charged ions and negatively charged electrons. These plasma particles are influenced by electric and magnetic fields that direct and accelerate the particles through space. Weather in space around the earths magnetosphere results from an interaction between the earth's magnetic field and solar wind. II.
(IMAGE) The IMAGE - "Imager for Magnetosphere-to Aurora-Global-Exploration"- space- craft, was launched in 2000 and carry's several sophisticated instruments that are used to observe the previously invisible areas of the inner magnetosphere. IMAGE will also investigate the mystery of the earth's plasma sphere. The plasma sphere is a torus of cold dense plasma that surrounds the earth in the inner magnetosphere. "The plasma sphere has some well-guarded secrets," said Dr. Donald Carpenter of Stanford University. "We hope that some of these fine instruments of IMAGE will reveal them." The IMAGE spacecraft has on-board an extreme ultraviolet (EUV) imager that detects solar EUV photons that are scattered in the plasma sphere.
By using this (EUV) researchers will be able to study the global structure as well as dynamics of the plasma sphere and plasma pause. The body of the IMAGE spacecraft is only 2. 25 meters wide but the antennas make IMAGE one of the biggest sensors ever flown in space. III. Geometric Storms Geomagnetic storms are classified into two different types: recurrent and non-recurrent.
Recurrent storms occur from major disturbances in the magnetosphere when the interplanetary magnetic field turns southward and remains southward for a substantial period of time. Interplanetary Magnetic Field (IMF) is a part of the Sun's magnetic field that travels into interplanetary space by the solar wind. These storms are called recurrent storms because they occur every 27 days in accordance with the Sun's rotation period. Recurrent storms are most prominent during the declining phase of the suns cycle.
Non-recurrent storms occur for the most part during the solar maximum time of the sun cycle. The main phase of a geomagnetic storm can last as long as two to two and a half days. Until the early 1990's it was believed that solar flares triggered geomagnetic storms. Now it is believed that Coronal Mass Ejections (CME's) set off large geomagnetic storms.
CME's erupt off the active solar surface of the sun and blast magnetic plasma into space. CME's, discovered by spacecraft in the early 1970's, extend sometimes 2 million kilometers from the suns surface. CME's occur about once each week during the solar minimum part of the cycle to solar maximum rates two or more per day. CME's often occur at the same time as Solar Flares but not always. IV. Solar Wind Solar wind is the super-sonic flow of plasma into interplanetary space from the Sun's corona.
Solar Wind varies in density, velocity, temperature, and magnetic field properties. These differences are in response to shocks, waves, and turbulence that disrupt the interplanetary flow. Average velocity and density for solar winds are 468 km per second and 8. 7 protons per cubic centimeter. Solar winds sometimes originate at the coronal holes. Coronal holes are regions of the sun where the corona is dark.
Coronal holes are associated with "open" magnetic filed lines and are often found at the Sun's poles. V. Bastile Day Storm (July 15 th - 16 th) "Presentation" I have discussed the effects of space weather on humans as well as compared Space weather to terrestrial weather. The new space weatherman "IMAGE" has been introduced. Several space weather concepts have been discussed such as: Geometric storms, CME's, Solar Wind, IMF, Solar Flares, and the Bastile Day Storm. The Bastile Day Strom should have tied all of the aspects of space storms that I have discussed together.
Humans are at the beginning of understanding space weather. The IMAGE spacecraft is an excellent opportunity to expand on that knowledge. With new advancements in technology our knowledge of space weather should someday surpass even are wildest dreams.