Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM)

High-energy particles called cosmic rays constantly shower our planet. Protons are the most common cosmic ray particles, but electrons, helium nuclei and the nuclei of heavier elements make up a small percentage. All are direct samples of matter from interstellar space.

The Cosmic Ray Energetics And Mass mission for the International Space Station (ISS-CREAM) is designed to measure the highest-energy cosmic rays of any detector yet flown in space. The refrigerator-sized, 1.4-ton (1,300 kilogram) experiment will reside on the Exposed Facility platform extending from Kibo, the Japanese Experiment Module, after its launch in August 2017.

The mission's goal is learn more about the origin of cosmic rays and the acceleration mechanisms that drive them to extreme energies. ISS-CREAM is designed to detect cosmic rays with energies reaching 1,000 trillion electron volts (1 PeV), far beyond the reach of particle accelerators on Earth.

ISS-CREAM detects cosmic ray particles when they slam into the matter making up its instruments. First, a silicon charge detector measures the electrical charge of incoming particles, then layers of carbon provide targets that encourage impacts, producing cascades of particles that stream into electrical and optical detectors below while a calorimeter determines their energy. Two scintillator-based detector systems provide the ability to discern between singly charged electrons and protons. All told, ISS-CREAM can distinguish electrons, protons and atomic nuclei as massive as iron as they crash through the instruments.

See http://www.nasa.gov/feature/goddard/2017/new-mission-going-to-the-space-station-to-explore-mysteries-of-cosmic-rain