The 7-foot-long robotic arm on Perseverance can move a lot like yours. It has a shoulder, elbow and wrist "joints" for maximum flexibility. The arm lets the rover work as a human geologist would: by holding and using science tools with its "hand" or turret. The rover's own "hand tools" extract cores from rocks, takes microscopic images and analyzes the elemental composition and mineral makeup of Martian rocks and soil.

The rover's drill will use rotary motion with or without percussion to penetrate into the Martian surface to collect the precious samples. The drill is equipped with three different kinds of attachments (bits) that facilitate sample acquisition and surface analysis. The coring and regolith bits are used to collect Martian samples directly into a clean sample collection tube, while the abrader bit is used to scrape off or "abrade" the top layers of rocks, to expose fresh, un-weathered surfaces for study. Types of Rock Samples the Drill will Collect

Rock Samples The cylindrical drill cuts out samples from rock interiors, breaking off the rock sample at its base. Each sample is collected directly into a clean sample collection tube. The sample tubes are about the size of a penlight. Each collected core is 0.5 inches (13 millimeters) in diameter and 2.4 inches (60 millimeters) long, amounting to an average of 10-15 grams of Martian material per tube.

"Regolith" Samples A special drill bit is used to collect the loose rocky material, or "regolith," on the Martian surface. As with rock samples, regolith samples are collected directly into a clean sample collection tube. Sampling Equipment on the "Hand" (Turret)

At the end of the arm is the "turret." It's like a hand that carries scientific cameras, mineral and chemical analyzers for studying the past habitability of Mars, and choosing the most scientifically valuable sample to cache. The scientific tools mounted on the turret are:

SHERLOC and WATSON SHERLOC is meant to study minerals up close, so it is mounted on the turret where it can be placed next to its targets. SHERLOC uses spectrometers, a laser and a camera to search for organics and minerals that have been altered by watery environments and may be signs of past microbial life.

SHERLOC has a helper. The WATSON camera is also mounted on the "hand/" It is like a geologist's hand-lens, magnifying and recording textures of rock and soil targets that are studied by the SHERLOC mineral analyzer. Its position on the agile turret of the robotic arm means WATSON can be placed near targets within the arm's reach. WATSON is also an integral camera "assistant" to SHERLOC and PIXL. WATSON also provides valuable views of rover systems such as the wheels and instruments mounted low on the rover, out of Mastcam-Z's view.

PIXL is mounted on the turret because it needs to be able to move close to its mineral targets. It is capable of detecting signs of past life. PIXL seeks changes in textures and chemicals in Martian rocks and soil left behind by any ancient microbial life. PIXL will study candidate specimens possible sample collection. The information it gathers will be used to decide which ones are the most scientifically interesting targets.

The turret has a special sensor to guard against damage if the arm comes into contact with the surface. The contact sensor signals the rover arm to stop if it inadvertently touches the ground.