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 spacecraft, robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity (rover), Curiosity'', a Mars rover, in Gale (crater), Gale Crater on Augus ...

''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 a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

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. Long-term proposals have included sending settlers and terraforming the p ...

, 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 deve ...

(SwRI) and the extraterrestrial physics group at Christian-Albrechts-Universität zu 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 Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the varying conditions within the Solar System and its heliosphere. This includes the effects of the solar wind, especially on the Earth's magnetosphere, ion ...

. The arrival of

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

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

Galactic cosmic radiation Cosmic rays or astroparticles 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 Sola ...

. 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 Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

. In September 2017, NASA reported

radiation levels Ionizing (ionising) radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionize atoms or molecules by detaching electrons from them. Some par ...

on the surface of Mars were temporarily doubled, and were associated with an

aurora An aurora ( aurorae or auroras), also commonly known as the northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in Earth's sky, predominantly observed in high-latitude regions (around the Arc ...

25-times brighter than any observed earlier, due to a massive, and unexpected,

Solar particle event In solar physics, a solar particle event (SPE), also known as a solar energetic particle event or solar radiation storm, is a solar phenomenon which occurs when particles emitted by the Sun, mostly protons, become accelerated either in the Sun's ...

and associated

solar storm A solar storm is a disturbance on the Sun, which can emanate outward across the heliosphere, affecting the entire Solar System, including Earth and its magnetosphere, and is the cause of space weather in the short-term with long-term patterns compr ...

in the middle of the month.

Astrobiology

The radiation sources that are of concern for

human health Health has a variety of definitions, which have been used for different purposes over time. In general, it refers to physical and emotional well-being, especially that associated with normal functioning of the human body, absent of disease, pain ...

also affect microbial survival as well as the preservation of organic chemicals and

biomolecule A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. Biomolecules include large macromolecules such as proteins, carbohydrates, lipids ...

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 Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...

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