Space Technology 5 (ST5) flight tested its miniaturized satellites and innovative technologies in the harsh environment of Earth's magnetosphere. In orbit, ST5's satellites mapped the intensity and direction of magnetic fields within the inner magnetosphere. These measurements will allow us to directly infer the presence of electrical currents carried by energetic charged particles.

Studying this region may help us understand the space weather that disrupts our communication, navigation, and power systems. For, while the magnetosphere acts as Earth's "suit of armor," deflecting most of the charged particles blasting out from the Sun, some do get through. These particles cause geomagnetic storms that can cause widespread power blackouts and damage satellites, sometimes permanently. They are also potentially harmful to any astronauts on duty in orbit.

Artist's concept of solar activity. Source: Endo, Japan.

Currently scientists don't know enough about solar activity to accurately forecast space weather and thereby minimize its harmful effects on space and ground based systems. We know that solar flares (explosions on the Sun's surface) and coronal mass ejections (ejected gas bubbles) project the Sun's plasma outward. We know that the solar wind carries this plasma through interplanetary space, where it eventually reaches Earth's "protective shield," the inner magnetosphere. We know that this "shield" deflects much of the solar wind plasma and solar energetic particles emanating from the Sun.

However, "radiation belts" still surround the Earth at altitudes of ~ 3,000 to 30,000 kilometers (1,864 to 18,641 miles) and present a hazard to satellites orbiting at these distances. And, some of the mass and energy carried by solar wind does get through.

The advanced technologies flight validated on ST5 will enable the success of future micro-sat or nanosat missions, such as the Magnetospheric Constellation. Such missions will provide global coverage of the magnetosphere as it reacts to major events on the Sun and during geomagnetic storms and substorms. The result will be a better understanding of the Earth's magnetosphere and a great improvement in our operational response to these events.