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A Public Outreach Module:
Solar Wind, Genesis, and the Planets

Spacecraft and the Earth's Magnetosphere

Satellites inside the Earth’s Magnetosphere
Normally the magnetosphere provides a degree of shielding and protection to satellites within its borders, but satellites orbiting earth are particularly vulnerable to blasts of solar energy resulting from the sun's high-energy eruptions. The effects vary according to the satellite's orbit, its position relative to certain regions in space, and the stage of the Solar Max cycle.

Satellites in the highest orbits are susceptible to bursts of high energy particles being trapped in the radiation belts that result from the interaction of an interplanetary shock with the magnetosphere. When these conditions create a sufficient pressure to push the boundary of the Earth's magnetosphere into the region of these satellites' orbits, satellites on the sunward side of the Earth are directly exposed to the full force of the solar particle radiation. These high speed, subatomic particles can move right through the thin metallic skin of a spacecraft damaging the microchip electronics inside and affecting the solar cells used to power nearly all Earth-orbiting satellites. Some spacecraft have had the efficiency of their solar cell reduced by over 30% in a single large solar particle event.

International Space StationAlthough those satellites in low orbits of about 1,000 kilometers are less susceptible to particle damage (except over the polar regions), they may suffer increased orbital decay when increased solar activity occurs.

Ultraviolet and X-ray emissions during periods of high solar flare activity can increase the temperatures in the upper atmosphere to almost three times those experienced in periods of low activity, resulting in an outward expansion of the atmosphere and a gas density increase in locations of satellites' orbit. This swelling can cause drag on satellites in low orbit; this includes the International Space Station, which can lose up to 1 km of altitude in a day due to such an event.

Spacecraft outside the Earth’s Magnetosphere
Voyager SpacecraftSpacecraft outside the protection of the Earth's atmosphere experience "charging" from increases in UV rays and X-rays. Sunlit parts of the spacecraft bleed off charge due to the photoelectric effect, but when satellites are in the Earth's shadow, they can experience significant charging. Spacecraft skin is generally conducting, but energetic particles can cause charging of underlying portions just under the skin, because they penetrate through the skin. Less energetic particles also contribute to a variety of spacecraft surface charging problems, especially during periods of high geomagnetic activity. In addition, energetic electrons responsible for deep dielectric charging can degrade the useful lifetime of internal components.

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For a more technical description, take a Closer Look at
The Structured Sun and Solar Max: At the Core of the Matter

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Curator: Aimee Meyer
Updated: November 2009

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