Robotic exploration of the Martian surface will provide important scientific data on planetary climate, life history, and geologic resources. In particular, robotic arms will assist in the detailed visual inspection, instrumented analysis, extraction, and earth return of soil and rock samples. To this end, we are developing new robotic manipulation concepts for use on landers and rovers, wherein mass, volume, power and the ambient Mars environment are significant design constraints. Our earlier work led to MarsArmI, a 2.2 meter, 3-dof hybrid metal/composite, dc-motor actuated arm operating under coordinated joint-space control; NASA's Mars Surveyor '98 mission utilizes this design concept. More recently, we have conceived and implmented new, all- composite, very light robot arms: MarsArmII, a 4.0 kilogram, 2.3 meter arm for lander operations, and MicroArm-1 and MicroArm-2, two smaller 1.0+ kilogram, .7 meter rover arms for mobile sample acquisition and Mars sample return processing. Features of these arms include our creation of new 3D machined composites for critical load-bearing parts; actuation by high-torque density ultrasonic motors; and, visually-designated inverse kinematics positioning with contact force adaptation under a novel task-level, dexterous controls paradigm. Our demonstrated results include robotic trenching, sample grasp-manipulation-and-transfer, and fresh rock surface exposure-probing via the science operator's 'point-and-shoot' visual task designation in a stereo workspace. Sensor-referenced control capabilities include real-time adaptation to positioning error and environmental uncertainties (e.g., variable soil resistance and impediments), and the synthesis of power optimal trajectories for free space manipulation.