SAMPEX Mission Returns to Earth

An artist’s rendition of the Solar, Anomalous, and Magnetospheric Particle Explorer or SAMPEX. Image courtesy of NASA

A NASA satellite — the Solar, Anomalous, and Magnetospheric Particle Explorer or SAMPEX — plunged toward Earth on Nov. 13, burning up completely in the atmosphere and closing the book on one of the most productive space weather observation platforms of all time.

SAMPEX launched from Vandenberg AFB on July 3, 1992. Its mission was to study the zoo of particles and cosmic rays surrounding Earth. Its original mission life was expected to be three years, but it survived much longer.

Aerospace was involved with SAMPEX until the very end of its life.

When SAMPEX launched, the sun was just finishing the peak of its 11-year solar cycle and beginning to move toward solar minimum. Scientists were eager to watch what happened in near-Earth space in those first few years, as eruptions on the sun shot out energy and solar material and eventually tapered down into a period of quiet.

In its two decades, SAMPEX provided one of the main sources of data on how the radiation environment around Earth changed over time, waxing and waning in response to incoming particles from the sun and galaxy. SAMPEX confirmed earlier theories that cosmic rays streaming in from outer space were being trapped in Earth’s own magnetic environment, the magnetosphere, and it helped pinpoint the location where they gathered in a belt around Earth.

Another area of research has been to tease out the composition of various particle populations, from high-speed and high-energy particles from the sun known as solar energetic particles, to the host of electrons in Earth’s middle atmosphere. Also, SAMPEX has been one of our best eyes on the radiation belts – two giant donuts of radiation surrounding Earth that can affect satellites in orbit during their occasional bouts of swelling.

SAMPEX’s science mission officially ended in June 2004. But new data continued to become available to the science and space communities thanks to The Aerospace Corporation, which downloaded data from the satellite until the very end. Bowie State University in Bowie, Md., operated the spacecraft as an educational tool for its students.

The work of SAMPEX will now be expanded upon by the Radiation Belt Storm Probes mission, which launched last August. The two-satellite mission contains five instruments built by Aerospace aboard each satellite.