03.21.2017 Break in Raised Tread on Curiosity Wheel
02.27.2017 Swirling Dust in Gale Crater, Mars, Sol 1613
02.27.2017 Dust Devil Passes Near Martian Sand Dune
02.27.2017 Sand Moving Under Curiosity, One Day to Next
12.13.2016 Now and Long Ago at Gale Crater, Mars
12.13.2016 Where's Boron? Mars Rover Detects It
10.03.2016 Curiosity Self-Portrait at 'Murray Buttes'
10.03.2016 Butte 'M9a' in 'Murray Buttes' on Mars
09.19.2016 Ribbon Cutting
09.09.2016 Farewell to Murray Buttes (Image 5)
09.09.2016 Farewell to Murray Buttes (Image 4)
09.09.2016 Farewell to Murray Buttes (Image 3)
09.09.2016 Farewell to Murray Buttes (Image 2)
09.09.2016 Farewell to Murray Buttes (Image 1)
08.26.2016 Out-of-this-World Records
03.30.2016 Erisa Hines
03.30.2016 Buzz Aldrin
02.12.2016 Women in Science
02.09.2016 Adam Steltzner, a JPL engineer
01.27.2016 Night Close-up of Martian Sand Grains
01.27.2016 Curiosity Self-Portrait at Martian Sand Dune
12.17.2015 Alteration Effects at Gale and Gusev Craters
12.17.2015 Full-Circle View Near 'Marias Pass' on Mars
12.11.2015 Surface Close-up of a Martian Sand Dune
12.11.2015 Martian Sand Disturbed by Rover Wheel
Physics of How DAN on Curiosity Checks for Water, Part 2This diagram and the one at PIA16916 illustrate how the Dynamic Albedo of Neutrons (DAN) instrument on NASA's Curiosity Mars rover detects hydrogen in the ground beneath the rover. Detected hydrogen is interpreted as hydroxyl groups or water molecules, such as those bound into the structure of hydrated minerals.
DAN shoots neutrons into the ground and measures the timing and energy levels of neutrons reflected back up. This diagram depicts the case of a neutron that collides with hydrogen atoms before it reaches DAN's detector. Collisions with hydrogen nuclei -- of similar mass to the neutron itself, like two billiard balls -- result in a change in energy level and a change in the time interval between when the neutron is emitted by DAN's neutron generator and when it reaches DAN's detector, compared with neutrons that do not collide with hydrogen, as in the companion diagram.
Russia's Space Research Institute, in Moscow, developed the DAN instrument in close cooperation with the N.L. Dukhov All-Russia Research Institute, Moscow, and the Joint Institute of Nuclear Research, Dubna.
Image Credit: NASA/JPL-Caltech/Russian Space Research Institute