is the concept of changing environmental conditions in outer space
. It is distinct from the concept of weather
within a planetary atmosphere
, and deals with phenomena involving ambient plasma
, magnetic fields, radiation
and other matter
in space (generally close to Earth but also in interplanetary
, and occasionally interstellar space
). "Space weather describes the conditions in space that affect Earth and its technological systems. Our space weather is a consequence of the behavior of the sun, the nature of Earth's magnetic field, and our location in the solar system."
Within our own solar system, space weather is greatly influenced by the speed and density of the solar wind and the interplanetary magnetic field (IMF) carried by the solar wind plasma. A variety of physical phenomena are associated with space weather, including geomagnetic storms and substorms, energization of the Van Allen radiation belts, ionospheric disturbances and scintillation, aurora and geomagnetically induced currents at Earth's surface. Coronal Mass Ejections and their associated shock waves are also important drivers of space weather as they can compress the magnetosphere and trigger geomagnetic storms. Solar Energetic Particles, accelerated by coronal mass ejections or solar flares, are also an important driver of space weather as they can damage electronics onboard spacecraft and threaten the life of astronauts.
Space weather exerts a profound influence in several areas related to space exploration and development. Changing geomagnetic conditions can induce changes in atmospheric density causing the rapid degradation of spacecraft altitude in Low Earth orbit. Geomagnetic storms due to increased solar activity can potentially blind sensors aboard spacecraft, or interfere with on-board electronics. An understanding of space environmental conditions is also important in designing shielding and life support systems for manned spacecraft. There is also some concern that geomagnetic storms may also expose conventional aircraft flying at high latitudes to increased amounts of radiation.
Satellites observing space weather
, the joint NASA
-European Space Agency Solar and Heliospheric Observatory
(SOHO) spacecraft is the main source of near-real time
solar data for space weather prediction. It was joined in 1998 by the NASA Advanced Composition Explorer (ACE), which carries a space weather beacon for continuous transmission of relevant in situ space environment data. SOHO and ACE are located near the L1 Lagrangian point, 1% of the earth-sun distance upstream of the earth where it measures solar wind plasma and magnetic field approximately one hour before it reaches the earth. Most recently, the launch of the NASA-ESA Solar-Terrestrial Relations Observatory (STEREO
) added an additional space weather data stream that covers the region between the sun and the earth with stereoscopic imagery. The two STEREO spacecraft drift away from the earth by about 22deg per year, one leading and the other trailing the earth in its orbit.
Major modelling efforts to simulate the space environment from the Sun to the Earth and beyond using three-dimensional global Magnetohydrodynamics frameworks
have been undertaken since the 1990s. In the United States, the two major centers are the Center for Space Environment Modeling
(CSEM) and the Center for Integrated Space weather Modeling
Examples of space weather events
- 1859 Sept 2, disruption of telegraph service.
- The best-known example of space weather events is the collapse of the HydroQuebec power network on March 13, 1989 due to geomagnetically induced currents. This was started by a transformer failure, which led to a general blackout, which lasted more than 9 hours and affected 6 million people. The geomagnetic storm causing this event was itself the result of a Coronal Mass Ejection, ejected from the Sun on March 9, 1989.
- A geomagnetic storm on January 20, 1994 temporarily knocked out two Canadian communications satellites, Aniks E1 and E2.
- A Coronal Mass Ejection on January 7, 1997 hit the Earth's magnetosphere on January 10 and caused the loss of the AT&T Telstar 401 communication satellite (a $200 million value).
- Transpolar routes flown by airplanes are particularly sensitive to space weather, in part because of Federal Aviation Regulations requiring reliable communication over the entire flight. It is estimated to cost about $100,000 each time such a flight is diverted from a polar route. Nine airlines are currently operating polar routes.
See also RAIM
- No large Solar Energetic Particles event happened during a manned mission. However, such a large event happened on August 7, 1972, between the Apollo 16 and Apollo 17 lunar missions. The dose of particles which would have hit an astronaut outside of earth's protective magnetic field, had this event happened during one of these missions, would have been deadly or at least life-threatening. Nozomi Mars Probe was hit by a large Solar Energetic Particles event on April 21, 2002, which caused large-scale failure. The mission, which was already about 3 years behind schedule, was eventually abandoned in December 2003.
Space weather at the Earth’s surface
The best known ground-level consequence of space weather is geomagnetically induced currents, or GIC. These are damaging electrical currents that can flow in power grids, pipelines and other conducting networks. Rapid magnetic changes on the ground - that occur during geomagnetic storms and are associated with space weather - can also be important for activities such as geophysical mapping and hydrocarbon production.
Air and ship borne magnetic surveys can be affected by rapid magnetic field variations during geomagnetic storms. Storms can cause data interpretation problems where the magnetic field changes due to space weather are of similar magnitude to those of the sub-surface crustal magnetic field in the survey area. Accurate geomagnetic storm warnings, including an assessment of the magnitude and duration of the storm, allows for an economic use of survey equipment.
Geophysics and Hydrocarbon Production
For economic and other reasons, oil and gas production often involves the directional drilling of well paths many kilometres from a single wellhead in both the horizontal and vertical directions. The accuracy requirements are strict, due to target size – reservoirs may only be a few tens to hundreds of metres across – and for safety reasons, because of the proximity of other boreholes. Surveying by the most accurate gyroscopic method is expensive, since it can involve the cessation of drilling for a number of hours. An alternative is to use a magnetic survey, which enables measurement while drilling (MWD). Near real time magnetic data can be used to correct the drilling direction and nearby magnetic observatories prove vital (Clark and Clarke, 2001; Reay et al, 2006). Magnetic data and storm forecasts can also be helpful in clarifying unknown sources of drilling error on an on-going basis.
- Clark, T. D. G. and E. Clarke, 2001. Space weather services for the offshore drilling industry. In Space Weather Workshop: Looking Towards a Future European Space Weather Programme. ESTEC, ESA WPP-194.
- Carlowicz, M. J., and R. E. Lopez, 2002, "Storms from the Sun", Joseph Henry Press, Washington DC.
- Reay, S. J., W. Allen, O. Baillie, J. Bowe, E. Clarke, V. Lesur, S. Macmillan, 2005. Space weather mom on drilling accuracy in the North Sea. Annales Geophysicae, Vol. 23, pp 3081-3088.
- Odenwald, S. 2006, "The 23rd Cycle;Learning to live with a stormy star", Columbia University Press, (http://www.astronomycafe.net/weather.html)