ISS-CREAM installed outside space station

A photo illustration of the location of the CREAM experiment. Credit: NASA

One of the external payloads that rode uphill with SpaceX's CRS-12 Dragon spacecraft was the Cosmic Ray Energetics and Mass Investigation, or CREAM (sometimes referred to as ISS-CREAM). This instrument, which is designed to look for the origins of cosmic rays, has now been attached to the exposed facility on the Japanese Kibo module.

CREAM was installed on Aug. 22, 2017. According to NASA, it is now observing cosmic rays coming from across the galaxy.

Cosmic rays are high-energy radiation originating from outside of the Solar System. They are composed mainly of high-energy protons and atomic nuclei and their origin has been a mystery ever since their discovery in 1912. 

The space-based astrophysics experiment is actually a follow-up of six other CREAM experiments. The key difference, however, is the previous experiments were launched on high-altitude balloons from McMurdo Station in Antarctica. These stayed aloft high in earth's atmosphere for up to 100 days to gather data about cosmic rays via detectors.

According to NASA, these detectors measure the charges of cosmic rays ranging from hydrogen up through iron nuclei over a broad energy range. Putting the hardware in orbit gives an order of magnitude more data with less interference from Earth.

Discovering the origins of these rays and what causes them to accelerate to such high speeds will also help build a stronger understanding of the fundamental structure of the universe.