ard Space Weather Center in Greenbelt, Md. who has been involved with SAMPEX research since its launch. "It was proposed as a minimum one-year mission with a goal of three years, but it lasted for an unexpectedly long time. It has provided 20 years of high quality data, used by nearly everyone who studies near-Earth space."
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. Indeed, scientists are eager for SAMPEX data still, eking out the last weeks of observation time to compare with early data from the Radiation Belt Storm Probes (RBSP) mission that launched in August, 2012.
When those who study the radiation belts realized how imminent was the demise of SAMPEX, they adjusted the schedule to turn on a SAMPEX-compatible instrument aboard RBSP, an instrument called Relativistic Electron Proton Telescope (REPT), earlier than planned. One of the space phenomena that SAMPEX has helped categorize is something called microbursts, an intense but short lived phase during which electrons drop out of the radiation belts.
From its viewpoint under the radiation belts, SAMPEX can still record such microbursts.
As part of RBSP, on the other hand, REPT can look at the electron population while traveling through the radiation belts proper. In combination, the data may help show what occurrences in the radiation belts correlate to the rain of electrons, the microbursts.
"Since one of the main goals of RBSP is to understand why and how electrons rain down out of the radiation belts, this will be important science," says Kanekal. "It's made all the more impressive that we can do this kind of research despite the fact that SAMPEX's science mission officially ended in 2004."
Although the spacecraft has remained in orbit, the official SAMPEX science mission ended in June 2004. New data remained available, however, thanks to The Aerospace Corporation of El Segundo, Calif., which continued to fund costs to download data, and to Bowie State University in Bowie, Md., which operated the spacecraft to maintain the download process as an educational tool for its students. Kanekal was also instrumental in getting a grant to process all the data from 2004 to 2012, so it will be usable by the science community.
NASA's first small explorer had an impressive run, far outliving its planned three-year mission. It provided data crucial to understanding how the space around Earth responds to space weather from the sun and will continue to do so up until the moment it re-enters Earth's atmosphere, disappearing forever.
Sun-Earth at NASA
Solar Science News at SpaceDaily
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