Radiation Assessment Detector seen by left Mastcam

The Radiation Assessment Detector (RAD) is an instrument mounted on the

Mars Science Laboratory Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity'', a Mars rover, in Gale Crater on August 6, 2012. The overall objectives include investigati ...

''Curiosity'' rover. It was the first of ten instruments to be turned on during the mission.

Purpose

The first role of RAD was to characterize the broad spectrum of

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, vi ...

environment found inside the spacecraft during the cruise phase. These measurements have never been done before from the inside of a spacecraft in interplanetary space. Its primary purpose is to determine the viability and shielding needs for potential human travelers on a

human mission to Mars The idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies since the late 1940s as part of the broader exploration of Mars. Some have also considered exploring the Martian moons of Phobos and Deim ...

, as well as to characterize the radiation environment on the surface of Mars, which it started doing immediately after MSL landed in August 2012. Turned on after launch, the RAD recorded several radiation spikes caused by the Sun. RAD is funded by the Exploration Systems Mission Directorate at NASA Headquarters and Germany's Space Agency (DLR), and developed by the

Southwest Research Institute Southwest Research Institute (SwRI), headquartered in San Antonio, Texas, is an independent and nonprofit applied research and development (R&D) organization. Founded in 1947 by oil businessman Tom Slick, it provides contract research and develo ...

(SwRI) and the extraterrestrial physics group at

Christian-Albrechts-Universität zu Kiel Kiel University, officially the Christian-Albrecht University of Kiel, (german: link=no, Christian-Albrechts-Universität zu Kiel, abbreviated CAU, known informally as Christiana Albertina) is a public research university in the city of Kiel ...

, Germany.NASA – RAD
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Results

On 31 May 2013, NASA scientists reported the results obtained during cruise, and stated that the equivalent dose radiation for even the shortest round-trip with current propulsion systems and comparable shielding is found to be . This implies a great health risk caused by energetic particle radiation for any

. In addition to assessing the radiation environment at Mars, data from RAD can also be used for the study of space weather. The arrival of

coronal mass ejection A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accep ...

s at Mars can be detected in RAD data through the Forbush decreases that their passage causes in the

Galactic cosmic radiation Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

. These measurements have led to the finding that fast CMEs can continue to decelerate even beyond Earth orbit when dragged by slower surrounding

solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the ...

. In September 2017, NASA reported radiation levels on the surface of Mars were temporarily doubled, and were associated with an

aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

25-times brighter than any observed earlier, due to a massive, and unexpected, Solar particle event and associated solar storm in the middle of the month.

Astrobiology

The radiation sources that are of concern for human health also affect microbial survival as well as the preservation of organic chemicals and

biomolecule A biomolecule or biological molecule is a loosely used term for molecules present in organisms that are essential to one or more typically biological processes, such as cell division, morphogenesis, or development. Biomolecules include larg ...

s. The RAD is currently quantifying the flux of biologically hazardous radiation at the surface of Mars today, and will help determine how these fluxes vary on diurnal, seasonal, solar cycle and episodic (flare, storm) timescales. These measurements will allow calculations of the depth in rock or soil to which this flux, when integrated over long timescales, provides a lethal dose for known terrestrial microorganisms. Through such measurements, scientists can learn how deep below the surface life would have to be, or have been in the past, to be protected. Research published in January 2014 of data from RAD, state that " ionizing radiation strongly influences chemical compositions and structures, especially for water, salts, and redox-sensitive components such as organic matter." The report concludes that the ''in situ'' "surface measurements —and subsurface estimates— constrain the preservation window for Martian organic matter following exhumation and exposure to ionizing radiation in the top few meters of the Martian surface.

Gallery

References

External links