10. Geospace Resource

The Sun and geospace Resource GS1 K. Endo/Nikkei Science BAS The aurora over the BAS Halley Research Station. Inset: Artist’s impression of the Sun and geospace (not to scale) illustrating how particles flowing radially from the Sun are deflected by the Earth’s magnetic field which forms a cavity in the particle stream, known as the magnetosphere. Solar wind – magnetosphere interaction Resource GS2 An illustration of the interaction between the solar wind and magnetosphere. Solar wind streamlines are deflected by a shock wave to flow around the magnetosphere in a turbulent layer known as the magnetosheath. Some solar wind plasma leaks inside the magnetosphere. In the magnetosphere particles are guided in spiral helical trajectories along magnetic field lines. Some of these precipitate into the atmosphere to create the aurora. SUN BAS The aurora over Antarctica Resource GS3 Professor L.A. Frank (University of Iowa) A satellite view of Antarctica showing the aurora encircling it The effects of space weather on human activity Resource GS4 Effects on satellites radiation belts. Similarly, the continuous the Hubble Space Telescope. These boosts Satellites often operate in the space bombardment by atoms in the thin upper again add to costs. environment for many years. As a result, atmosphere can alter orbits and wear they can sustain long-term exposure surfaces away. Some materials become Effects on power systems effects in addition to special ‘space storm’ brittle from long-term exposure to solar Electric power systems on the ground problems. Depending upon their orbit, ultraviolet light above the protective can be affected by the enhanced satellite electronic components, solar absorbing atmosphere of Earth. Single currents that flow in the magnetosphere- cells, and materials degrade from the penetrating energetic particles (from ionosphere system during geospace accumulated radiation dose caused by the Van Allen belts or cosmic rays) can storms. These currents cause magnetic repeated traversals of the Van Allen change the information stored in elec- field perturbations on the ground that in tronics components such as spacecraft EPRI turn induce other currents in long memory chips by flipping binary values Map of power disruption in North America, transmission lines, especially those that encode the information. due to a space weather storm in March 1989 located at high latitudes. The slowly A particular ‘danger zone’ for low- propulsion systems. This appeared to varying DC part of the currents can be altitude spacecraft is in the region of happen with the Canadian ANIK E1 and large enough to cause overheating and the South Atlantic, where the energetic E2 satellites. They experienced a loss of damage to systems designed for AC. particle populations in the radiation belts systems during an interval of elevated Disruption of power distribution systems can reach unusually low altitudes due to intensity of high-energy electrons in the can adversely affect many aspects of our a local weakness in the Earth’s magnetic Earth’s outer magnetosphere. daily lives should a blackout result. field. Space weather ‘storms’ add new The upper atmosphere becomes inflated problems while exacerbating the cumul- if it is heated by extra energy sources Effects on pipelines ative effects. Some satellites charge up such as auroral particles and enhanced Space weather-induced currents similarly when they are suddenly immersed in resistive ionospheric currents. The flow in long conductors on the ground enhanced radiation environments in the resulting increased atmospheric particle such as oil pipelines. These currents Van Allen belts, the auroral zone, or inter- densities at 300–500 km altitude signific- create galvanic effects that lead to rapid planetary space. Component surfaces can antly increase the number of microscopic corrosion at the pipeline joints if they are charge to very high potentials compared collisions between the satellite and the not properly grounded. Such corrosion to the metallic surfaces of the satellite, surrounding gas particles. This increased requires expensive repairs or can lead to leading to discharges between the two. ‘satellite drag’ can alter an orbit enough permanent damage. Such discharges cause both material so that the satellite is temporarily ‘lost’ to damage and electrical currents on the communications links. It also causes the Effects on communications systems spacecraft. The latter can masquerade premature decay of the orbit. This can Short wave radio communication at HF as ‘phantom commands’ to spacecraft lead to early loss of the system with frequencies (3–30 megaHertz), which is elesat, Canada T systems. These events can cause a loss of associated financial implications or still extensively used by the military and Anik E1 satellite control of instruments and power or necessitate shuttle ‘boosts’ for some, like for overseas broadcasting in various Page 1 of 2 The effects of space weather on human activity Resource GS4 countries, depends upon the reflection of solar events likely to produce a geospace signals from the Earth’s ionosphere. The storm (such as a coronal mass ejection) signals are attenuated when the electron are less apparent. number density in the lower ionosphere Astronaut radiation exposure is a increases. This affects the usable radio major concern for manned space flight. communication frequencies and can Most manned missions occur in orbits cause a total communications blackout. that are below the regions where the Van Solar flare ultraviolet and x-ray bursts, Allen belt radiation is most intense. solar energetic particles, or intense Spacewalks in the region of anomalously aurora during geospace storms can all high radiation over the South Atlantic bring on this condition. need to be avoided. However, the Mir The changes in ionospheric attenuation space station and the International Space and reflection of electromagnetic waves Station (ISS) have orbits sufficiently also affect the use of ‘over-the-horizon’ inclined from the equator to bring them HF radars used to detect and monitor into the expanded auroral zones that aircraft and sea conditions. Ionospheric occur during geospace storms. The electron density irregularities also produce likelihood of a frequently disturbed noise or ‘clutter’ in the radar signals. magnetosphere and presence of solar energetic particles is considerable given Effects on navigation systems the phasing of the ISS construction with The same disturbance-related changes the next solar maximum. in the Earth’s ionosphere that affect NASA For missions that leave low-Earth orbit, View of Earth across the cargo bay of the Space Shuttle communications introduce changes in like the Apollo missions to the Moon, the the time it takes signals to traverse the survey data that can be mistaken protection from cosmic rays and solar ability to rapidly traverse the radiation ionosphere. The abnormal time delays for signatures of subsurface resources. energetic particles, there is still concern belts and to predict the occurrence introduce position errors and decrease Survey schedules or operations must for flights on polar routes during major of solar energetic particle events is the accuracy and reliability of the Global be modified, often suddenly and with solar particle events. The primary means essential. While proposed manned space- Positioning System (GPS), which is used significant costs, to avoid errors in the of reducing this hazard is to modify craft for future missions to Mars will for many range-finding and navigational survey data. flight paths as necessary and to limit the generally be equipped with shielded purposes. flight time of personnel on high-altitude astronaut shelters, adequate warning is Hazards to humans in space aircraft such as Concorde. It is clear necessary for these to be useful. Effects on geomagnetic surveys The principal space weather hazard to that in this case early warnings of An astronaut on the lunar surface Geomagnetic surveys are important tools humans is radiation exposure to astro- solar energetic particles are extremely would be in danger of a lethal dose of in the commercial exploration of natural nauts and passengers in high-altitude desirable. While some sources (solar radiation from solar energetic particles resources. However, space weather-related aircraft. Although the residual atmosphere flares) can be monitored at least on the were a major coronal mass ejection to perturbations can create signals in above an aircraft provides a measure of visible disk of the Sun, indications of occur unnoticed. This article is drawn from the views of the US National Academy of Sciences as expressed on their World Wide Website (http://nas.edu/ssb/spwptSnw.html) Page 2 of 2 Why study geospace in Antarctica? Resource GS5 Nightlights of the world as viewed by satellites in space, illustrating the lack of light pollution in Antarctica and its remoteness from industrialised areas. NOAA/USAF There are six compelling reasons for conducting frontier the solar wind energy transferred into the magnetosphere between the energy input to the upper atmosphere from experimental research on geospace physics in the and ionosphere is deposited in the high latitude regions, below, due to the different topography and albedo of the Antarctic: owing to the configuration of the Earth’s magnetic field. two hemispheres. One manifestation of this is the aurora. • The effects of the separation of the geographic and • The ionosphere above the Antarctic provides a viewing • The geospace environment deposits energy into both geomagnetic poles is most apparent in the Antarctic window through which to remotely sense nearly all regions north and south polar regions, but often in different Peninsula region compared to anywhere else on Earth. of geospace. A small region of the high latitude amounts. Simultaneous observations in both polar regions For this reason, solar and geomagnetic effects on the polar ionosphere senses large volumes of geospace via provide critical data to study this. Comprehensive upper atmosphere can be distinguished more readily geomagnetic field lines that diverge from the Earth’s instrumentation in Antarctica complements the similarly here. surface.

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