The Radiation Assessment Detector is also known as RAD, and is helping prepare for future human exploration of Mars. RAD measures the type and amount of harmful radiation that reaches the Martian surface from the sun and space sources.

Tech Specs

Main Job
Monitored the space radiation in space on the way to Mars and then on the surface as the rover roves. This information helps shape future human missions to Mars by letting us know how much shielding from radiation future Mars astronauts will need to protect them.
Location Rover Deck, pointed toward the sky.
Size Similar to a small toaster or six-pack of soda.

Radiation Assessment Detector (RAD)

Radiation Assessment Detector
Radiation Assessment Detector: About the size of a small toaster, the Radiation Assessment Detector will look skyward and use a stack of silicon detectors and a crystal of cesium iodide to measure galactic cosmic rays and solar particles that pass through the Martian atmosphere. Credit: NASA/JPL-Caltech/SwRI
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The Radiation Assessment Detector (RAD) is one of the first instruments sent to Mars specifically to prepare for future human exploration. The size of a small toaster or six-pack of soda, RAD measures and identifies all high-energy radiation on the Martian surface, such as protons, energetic ions of various elements, neutrons, and gamma rays. That includes not only direct radiation from the sun and space, but also secondary radiation produced by the interaction of radiation with the Martian atmosphere and surface rocks and soils.

To prepare for future human exploration, RAD collects data that allow scientists to calculate the equivalent dose (a measure of the effect radiation has on humans) to which people would be exposed on the surface of Mars. RAD also assesses the hazard presented by radiation to potential microbial life, past and present, both on and beneath the Martian surface. In addition, RAD investigates how radiation has affected the chemical and isotopic composition of Martian rocks and soils. (Isotopes are atoms of the same element having the same number of protons but a different number of neutrons).

Radiation Assessment Detector for Mars Science Laboratory
Radiation Assessment Detector for Mars Science Laboratory

A stack of paper-thin, silicon detectors and a small block of cesium iodide measure high-energy charged particles coming through the Martian atmosphere. As the particles pass through the detectors, they lose energy, producing electron or light pulses. An internal signal processor analyzes the pulses to identify each high-energy particle and determine its energy. In addition to identifying neutrons, gamma rays, protons, and alpha particles (subatomic fragments consisting of 2 protons and 2 neutrons, identical to helium nuclei), RAD can identify heavy ions up to iron on the periodic table. RAD is lightweight and energy efficient so as to use as little of the rover's available mass and energy resources as possible.

Curiosity's First Radiation Measurements on Mars
Curiosity's First Radiation Measurements on Mars