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The Cluster II spacecraft will fly in formation as tight as 200 km (120 mi) and as loose as 18,000 km (11,160 mi) as they orbit as far out as 10 times the diameter of the Earth. This way, scientists can measure small-scale turbulence in the magnetosphere and the solar wind. This will help scientists determine whether a set of conditions changing back and forth represents something like passing through the spiral arms of a storm or through separate storms. |
IMAGE will feature three unconventional "non-imaging" cameras. Instead of photons, they will collect neutral hydrogen, helium, and oxygen atoms. Because the energetic neutral atoms (ENA) are not controlled by the magnetic field, they fly in straight lines and can have starting points that are near or far. Nevertheless, with some complex equations to deconvolve the images, scientists will be able to build images that show heating regions that turned charged ions into neutralized atoms. Dr. Thomas Moore of NASA's Goddard Space Flight Center said the Low-Energy Neutral Atom camera is crossing a couple of "final frontiers." First, taking "pictures" in this manner requires a little trickery, such as rejecting ions and electrons that would fool the detector, then ionizing the neutral atoms so they can be detected, and using filters to keep out light that would further cloud the view. |
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This makes the camera an ambitious, high-risk instrument. But if it works, it will also pay off in sampling the neutral interstellar and solar winds when the camera is pointing away from the Earth. (Copies of the energetic neutral atom cameras will piggyback as TWINS - Two Wide-angle Imaging Neutral-atom Spectrometers - on two Department of Defense satellites in 2002 and 2004. Like a pair of eyes, they will give scientists a 3-D view of the large-scale structure and dynamics of the magnetosphere during 2004-06 when both spacecraft are operating.) |
Radio, too, will be used somewhat like a camera with IMAGE's Radio Plasma Imager (RPI), described in yesterday's story, charting the magnetosphere like weather radar watching storms. "The RPI is a revolutionary new instrument," said Dr. James Green, an RPI team member from NASA's Goddard Space Flight Center. "It will let us look at the dynamics of the magnetosphere as we never have before." |
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IMAGE will also carry more conventional cameras, like an Extreme Ultraviolet Imager that will observe helium ions trapped around the Earth. This was only done once before, when a special astronomy camera carried by Apollo 16 was aimed at Earth in 1972. IMAGE's EUVI is a triple camera that will see the energetic magnetosphere the light emitted by helium ions. Other missions being developed or proposed include:
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Sun-Earth connection - NASA's International Solar-Terrestial Physics mission The Exploration
of the Earth's Magnetosphere
- Goddard's intro to the Earth's Magnetosphere External links: |
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Dooling |