2002 SPACE SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| EARTH'S SPACE STORM SHIELD OFFERS PROTECTION - AT A PRICE
| G02-033 | 5/9/02 | 00:08:42 | New observations from a NASA spacecraft reval that a ;ayer in the Earth's out atmosphere acts like a heat shield by absorbing energy from space storms, which reduces their ability to heat the lower atmosphere. However, it imposes a heavy toll for its service by creating a billion-degree cloud of electrified gas, or plasma that surrounds our planet. The plasma cloud is so ferociously hot, its particles act like radiation, occasionally disrupting satellites in mid to high orbits. This discovery from NASA's Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft confirms that the Earth actively participates in space storms.
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TAPE CONTENTS: |
| ITEM (1): Magnetosphere Animation - As plasma from a solar storm impacts the Earth's magnetic field, oxygen ions are immediately ejected from the polar Ionosphere in response to the bursts of heating caused by the massive electrical current generated. The ejected ions flow outwrd along Earth's magnetic field lines toward the geotail. The pressure from the solar wind stretches the magnetic field toward the night-side of the Earth like a rubberband. When the stretching becomes too great, the night-side magnetosphere snaps back toward the Earth, carrying the ejected ions from the ionosphere with it like an enormous slingshot. These ions, now accelerated to enormous velocities (about 2,500 miles or 4,000 km/per second), appear immediately in the auroa and in the cloud of hot plasma that encircles the Earth during space storms.
Courtesy: NASA
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| ITEM (2): Ion Outflow - The upper atmosphere absorbs some of the energy that is input into it by the pressure pulses in the solar wind and, in response, it expels ions into the magnetosphere immediately. The Low Energy Neutral Atom Imager (LENA) instrument aboard the IMAGE spacecraft looks at the reaction Earth's atmosphere has input from the solar wind. This data was collected June 24, 2000, and shows the ion outflow over a period of almost one-hour. The data shows that the ion outflow is prompt in response to the solar wind changes.
Courtesy: NASA
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| ITEM (3): Expelled Ion Flow - Protection from the solar wind comes with a high price, because the expelled oxygen ions gain tremendous speed as they leave the atmosphere and become trapped by the Earth's magnetic field and ultimately encircle the earth, where they form a hot plasma cloud around the planet. data collected using the High Energy Neutral Atom Imager (HENA) aboard the IMAGE spacecraft shows that approximately half of the energy deposited by space storms in out atmosphere is absorbed this way. The sudden brightenings in oxygen emission represent arrival of the ejected oxygen in the hot plasma cloud but having gained about 100,000 times as much energy as it started out with in the ionosphere. The oxygen appears immediately in the aurora and in the cloud of hot plasma that encircles the earth during space storms.
Courtesy: NASA
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| ITEM (4): Ion Flow Animation - This animation is a simplified representation of the flow of plasma within the Earth's magnetic region. Plasma flows with the solar wind around the perimeter of the Earth's magnetic field and then returns through the interior of the system in a closed pair of flow cells.
Courtesy: NASA
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| ITEM (5): Circuit Analogy Animation - This animation draws an analogy between the aurora and a TV screen. In a television tube, accelerated electrons hit a phosphorescent screen and cause the phosphor to glow. The aurora works similarly; accererated electrons impact the atoms in the earth's upper atmosphere and causethem to glow; creating the aurora. The solar wind is the energy source, or voltage generator, for the circuit and the path the electrons follow through the earth's atmosphere near the poles acts like a resistor. But, unlike a television's TV tube, earth's ionosphere also contains positively charged ions and these ions are accelerated outward along Earth's magnetic field lines as electrons are accelerated downward.
Courtesy: NASA
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| ITEM (6): Cold Plasma Erosion Image - The strong circulation flow in the magnetosphere during space storms produces dramatic changes in the plasmasphere. a plume of plasma is stripped away, forming a plume of plasma that is carried toward tha sun. Ultraviolet sunlight ionizes our upper atmosphere producing the plasmasphere - a region nearest the earth whose particles are a cold, dense mixture of electrons and ions called a plasma.
Courtesy: NASA
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| ITEM (7): Plasmasphere Tails Can Effect Radio Navigation - The Extreme Ultraviolet (EUV) instrument on IMAGE captured this image sequence of the plasmasphere forming a plume. This view is from above the North Pole, with the Sun at the bottom of the picture. The fomation of a large-scale plasma plume can be seen in the lower right, a region where inner plasmasphere is being pulled away from the Earth and towards the Sun. The aurora is clearly seen at polar latitudes and the plasmasphere extends outward around the Earth. [The dark areas that sometimes appear come from an automatic gain reduction in the middle camera.] During a magnetic storm, strong circulation flows strip away the outer plasmasphere, and plasmaspheric plumes--long plumes with increased electron concentrations--are the result. These plumes extend down to the Ionosphere, where their edges cause deflection of radio waves. We use radio navigation signals from the Global Positioning Satellites (GPS) in all sorts of ways.
Courtesy: NASA
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| ITEM (8): Ionospheric Effects on the Global Positioning System - By combining the data from 150 ground-baesed GPS receivers and ground-based radar observations, the dramtic ionospheric structures spanning the North American continent can be seen. Large-scale features stretching from Washington, DC, over the Great Lakes, and into Canada, map directly into the plasmaspheric plumes seen in the IMAGE EUV observations. These plumes and clouds of ionization are a significant space weather hazard and can be responsible for the degradiation and breakdown of navigation and communication links. This new view of the plasmaspheric footprint is helping scientists to better understand the effects of space stroms.
Courtesy: NASA
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| ITEM (9): IMAGE Spacecraft Animation - Launched on March 25, 2000, the IMAGE spacecraft's mission objectives are: To help identify the dominant mechanisms for injecting plasma into the magnetosphere on substorm and magnetic storm time scales; Determine the directly driven response of the magnetosphere to solar wind changes; Discover how and where magnetospheric plasmas are energized, transported, and subsequently lost during substroms and magnetic storms.
Courtesy: NASA
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