Galactic Cosmic Rays (or GCRs) are high-energy particles that originate outside of our Solar System. These particles include protons, anti-protons, electrons, positrons and positively charged atomic nuclei whose ultimate origin is unknown to us. They are believed to have been created during stellar fusion processes, or created and subsequently accelerated during supernovae explosions. The energy levels in these particles can vary from 10^3 eV to more than 10^20 eV. Exactly how these particles can attain these energy levels is still unknown.

The highly energetic particles shed their orbital electrons, and thus become easily influenced by galactic magnetic field lines. For this reason, it is difficult to trace the exact path of any particle that we are able to detect here on Earth. Most GCRs that we can detect have most likely had encounters with supernovae remnants, solar wind from stars, and interstellar dust. These encounters would affect the energy level of the GCRs, altering their final characteristics when we detect them.

The Earth's upper atmosphere is constantly bombarded with GCRs. Here on the land surface of the Earth, we are protected by the many layers of the atmosphere. However, any person or object traveling above the Earth's atmosphere is vulnerable to the highly damaging effects that GCRs may have. With an incoming rate of nearly 100 particles per square meter per second, it is important to gather as much information on GCRs as possible so that we may understand not only their immediate effects, but also any effects which may come about in the future.