The extended robotic arm of NASA's Mars rover Curiosity can be seen in this mosaic of full-resolution images from Curiosity's Navigation camera (Navcam). Curiosity extended its arm on Aug. 20, 2012.
Curiosity's "arm"
The Robot Arm holds and maneuvers the instruments that help scientists get up-close and personal with martian rocks and soil.
Much like a human arm, the robotic arm has flexibility through three joints: the rover's shoulder, elbow, and wrist. The arm enables a tool belt of scientists' instruments to extend, bend, and angle precisely against a rock to work as a human geologist would: grinding away layers, taking microscopic images, and analyzing the elemental composition of the rocks and soil.
At the end of the arm is a turret, shaped like a cross. This turret, a hand-like structure, holds various tools that can spin through a 350-degree turning range.
Curiosity's "hand"
At the tip of the arm is the turret structure on which 5 devices are mounted. Two of these devices are in-situ or contact instruments known as the Alpha Particle X-ray Spectrometer (APXS) and the Mars Hand Lens Imager (MAHLI). The remaining three devices are associated with sample acquisition and sample preparation functions.
Hello, MAHLI
This image shows the Mars Hand Lens Imager (MAHLI) on NASA's Curiosity rover, with the Martian landscape in the background.