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RAD on MSL RAD Quick Facts
  • Nov 26, 2011
  • MSL Launched
  • Dec 6, 2011
  • RAD Turned On
  • Aug 6, 2012
  • MSL Arrives at Mars
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About RAD
The RAD Instrument

The Radiation Assessment Detector (RAD) is an investigation to detect and analyze the most biologically hazardous energetic particle radiation on the Martian surface as part of the Mars Science Laboratory (MSL) mission. It will make the first-ever direct radiation measurements on the surface of Mars, detecting galactic cosmic rays, solar energetic particles, secondary neutrons, and other secondary particles created both in the atmosphere and in the Martian regolith. The radiation environment on Mars is a key life-limiting factor that directly affects habitability and the ability to sustain life, and poses a challenge for future human explorers on the red planet. Thus, RAD measurements will aid planning for future human exploration and give us a direct measure of what levels of radiation to expect when we send astronauts to Mars in the future.

The RAD instrument combines charged- and neutral-particle detection capability over a wide dynamic range in a compact, low-mass, low-power instrument. These capabilities are required in order to measure all the important components of the radiation environment.

About MSL

Mars Science Laboratory is intended to be the first planetary mission to use precision landing techniques, steering itself toward the Martian surface similar to the way the space shuttle controls its entry through the Earth's upper atmosphere. In this way, the spacecraft will fly to a desired location above the surface of Mars before deploying its parachute for the final landing. As currently envisioned, in the final minutes before touchdown, the spacecraft will activate its parachute and retro rockets before lowering the rover package to the surface on a tether (similar to the way a skycrane helicopter moves a large object). This landing method will enable the rover to land in an area 20 to 40 kilometers (12 to 24 miles) long, about the size of a small crater or wide canyon and three to five times smaller than previous landing zones on Mars.

Curiosity at JPL

Like the Mars Exploration rovers (MER) now on the surface of Mars, Mars Science Laboratory will have six wheels and cameras mounted on a mast. It will carry a laser for vaporizing a thin layer from the surface of a rock and analyzing the elemental composition of the underlying materials. It will be able to collect rock and soil samples and distribute them to on-board test chambers for chemical analysis. Its design includes a suite of scientific instruments for identifying organic compounds such as proteins, amino acids, and other acids and bases that attach themselves to carbon backbones and are essential to life as we know it. It can also identify features such as atmospheric gases that may be associated with biological activity. Of course, it will also measure the radiation environment on the surface of Mars to assess the affect of radiation on habitability as well as aid planning for future human exploration, as discussed above.

NASA selected a landing site on the basis of highly detailed images sent to Earth by the Mars Reconnaissance Orbiter, in addition to data from earlier missions. The rover will carry a radioisotope power system that generates electricity from the heat of plutonium's radioactive decay. This power source gives the mission an operating lifespan on Mars' surface of a full martian year (687 Earth days) or more while also providing significantly greater mobility and operational flexibility, enhanced science payload capability, and exploration of a much larger range of latitudes and altitudes than was possible on previous missions to Mars.

Location of Curiosity relative to other Mars missions

Curiosity will land in a flat region of Gale crater which is situated on the rim of the Southern highlands, i.e., on the border of the highlands to the Northern basin. In its center Gale crater contains a large mound which is layered. These layers (stratigraphy) appear to have been deposited sequentially, possibly as sediments. The lowest layers contain minerals which on Earth are only known to form in the presence of liquid water. As one proceeds higher up through these layers, their origin appears to be drier and drier. Thus Gale crater offers a chronology of Mars which only needs to be read by MSL. It dates from early (Noachian) possibly wet Mars through middle-age (Hesperian) to modern (Amazonian) Mars. It may contain the key to understanding what went wrong in the history of Mars, why Mars is today so dry. Do the 'wet' deposits contain signs of life on Mars in the distant past? Are there other signs of life, possibly even in more recent deposits? MSL will be able to answer these questions.

Southwest Research Institute
Updated: 6 Jul 2012