Space WeatherMission Nears Launch
"Good evening space weather lovers! Last night Earth was hit by a high-pressure solar wind stream. It's expected to persist for 3 or 4 more days producing a 50% chance of mid-latitude aurora. If you were hoping to use your cell phone today -- forget it!"
One day, space weather forecasts like this could be commonplace. As our society comes to rely on satellites, cell phones, and other space-age gadgets, forecasting solar and geomagnetic storms can be just as important as knowing the chances of rain tomorrow. Unfortunately for technophiles, space weather forecasting is about 40 or 50 years behind everyday weather predictions.
Right: A cutaway diagram of the magnetosphere illustrates how IMAGE will observe the magnetosphere. For more information, visit the IMAGE home pages at the Southwest Research Institute and the Goddard Space Flight Center.
The magnetosphere is an area of space around our planet that is controlled by Earth's magnetic field. It helps keep out charged particles from the solar wind, including high-energy particles that come from solar flares and coronal mass ejections. The magnetosphere is not a perfect shield. When the Sun is very active, ionized gas is able to penetrate the magnetosphere and high-pressure solar winds can cause the magnetic field to be squeezed and buffeted.
During periods of gusty solar wind, powerful magnetic storms cause vivid auroras, radio and television static, power blackouts, and navigation problems for ships and airplanes with magnetic compasses. There can even be damage to satellites and spacecraft.
Predicting these events can be tricky, and often impossible, because scientists don't yet have a global view of how the magnetosphere works. During the past 40 years, space physicists have made many individual measurements of conditions at different points in the magnetosphere, but the overall picture of plasmas, fields, and flowing currents is missing.
"It's a little like looking at a thermometer in Alaska, checking the barometric pressure in Florida, and then trying to predict the weather in Europe," explains Dennis Gallagher (NASA/MSFC), an IMAGE Co-investigator responsible for the theory and modeling activity, and a member of the Radio Plasma Imager science team. "Assembling a global picture from a statistical collection of data is dicey. We've never been able to step back and see the whole thing. All of the instruments on IMAGE provide unique and wholly new ways of looking at the magnetosphere."
IMAGE is such a cutting-edge mission that it has been named as a semifinalist in two award competitions: Discover Magazine's Innovative Technology of the Year Award for 1999 and the Columbus Foundation Award.
To get the best view of this new frontier, IMAGE will be launched into an orbit that loops from a low point of 1,000 km (600 mi) to a high point of almost 45,000 km (almost 27,000 mi). From that vantage point, IMAGE's instruments will look back and be able to see the inner structure of the magnetosphere, including the magnetopause, the boundary where the magnetosphere meets interplanetary space.
Instruments on IMAGE include:
- The Radio Plasma Imager. The RPI will use radar echoes in the frequency range 3 kHz to 3 MHz to detect and monitor ionized gas (plasma) inside the magnetosphere.
- Far Ultraviolet Imager. The FUI will take pictures and spectra of the entire Earth along with the auroral oval at ultraviolet wavelengths. The 3 instruments that combine to form the FUI instrument package (GEO, SI and WIC) will provide almost constant monitoring of auroral activity from above our planet. The Earth is surrounded by a cloud of neutral atoms and molecules that is largely invisible from the ground. The so-called 'geocorona' is an extension of Earth's atmosphere into space. It is mostly made up of hydrogen, because it's the lightest element. GEO will also be used to detect these neutral atoms, measure their energy and map their distribution.
- Neutral Atom Imagers. The neutral atom cameras will detect neutral atoms created by ring current ions and escaping auroral ions that collide and exchange charge with the cold, geocoronal hydrogen gas. This will allow scientists to indirectly monitor and explore the ring current and auroral ion fountains.
- Extreme Ultraviolet Imager. The EUVI will detect ultraviolet photons from the Sun that are scattered by helium ions in the plasmasphere, a torus of cold dense plasma surrounding the Earth in the inner magnetosphere. A sophisticated deconvolution technique will be used to translate the photon counts into images of the plasmasphere.
Right: Click the image for a 3D simulation of the magnetosphere's shape. The Sun is off screen to the left. The animation begins showing the Earth, which recedes as the shape and size of the magnetosphere comes into view. The solar wind deforms the magnetosphere into its characteristic shape. Where the magnetosphere and the solar wind meet is the "bow shock," represented in the animation by a faint, translucent bullet shape. Credit: Digital Radiance
"Just think about how geosynchronous weather satellites changed things for meteorologists," said Gallagher. "Nowadays you can show anyone a satellite picture of a hurricane and they'll say, 'hey, that's a hurricane!' Now imagine how our field will change when we can look at pictures of ring currents, the plasmasphere and the magnetopause and watch them change in real time."
Science@NASA will follow this story with a series of science articles leading up to the launch of IMAGE, currently scheduled for March 15, 2000.
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For more news and information about space weather, please see SpaceWeather.com. Technical information about current space weather conditions may be found at the NOAA Space Environment Center.Web Links
IMAGE home page - from NASA/GSFC.
IMAGE home page - from the Southwest Research Institute.