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Hand-eye coordination

The first step in building a hand is learning how to reach out and touch accurately. This short video covers the initial testing after the hand was attached to the arm. At first the rover needs to learn how to move it's hand accurately, otherwise it could easily damage itself.

What can the hand do?

Curiosity takes a self portrait of it's hand. Image: NASA/JPL-Caltech/MSSSAt the tip of Curiosity’s arm is the turret structure on which 5 devices are mounted. Two of these devices are 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 Dust Removal (DRT), drilling and sample processing CHIMRA which we will cover next.

Location of key instruments on the hand. Image Credit: NASA/JPL

First, let’s cover Curiosity’s magnifying glass.

The Mars Hand Lens Imager (MAHLI)

The Mars Hand Lens Imager is the equivalent of a geologist's hand lens and will provide close-up views of the minerals, textures and structures in martian rocks and the surface layer of rocky debris and dust.

MAHLI is like a hand lens used by field geologists. Image: CCWith this new device, earthbound geologists will be able to see martian features smaller than the diameter of a human hair.

Actual size of imager. IMage: NASA/JPL-Caltech/MSSSThe primary objective of the MAHLI investigation is to acquire images, particularly those which facilitate the interpretation of the petrography and mineralogy of rocks and soil. Below is a MAHLI image of a zinc ore sample from Franklin, New Jersey. Note the 1 mm scale bar.

Image of zinc ore taken on earth using MAHLI. IMage: NASA/JPL-Caltech/MSS

Aside from snapping detailed photos we can also do high precision analysis of surface composition using X-rays.

Alpha Particle X-Ray Spectrometer (APXS)

The main objective of the APXS is to characterize the geology of the rover's surroundings and to investigate the processes that formed the rocks and soils.

This image shows the APXS pointing directly at us. IMage: NASA/JPL-Caltech/MSSSIt has a high precision detection for salt forming elements like S, Cl, and Br. It can detect trace amounts that would go undetected at a distance. The alpha particle X-ray spectrometer uses alpha particles and X-rays to determine the chemical makeup of martian rocks and soils.

Close-up of the emitter. Image: NASA/JPL-Caltech/Max-Planck-InstituteThe APXS will be placed in contact with rock and soil samples on Mars and will expose the material to alpha particles and X-rays emitted during the radioactive decay of the element curium. The X-ray energies enable scientists to identify all important rock-forming elements, from sodium to heavier elements.

Scooping dust

Most importantly we have the ability to take scoop and drill samples. This can be broken down into two phases:

Step 1: Sample Acquisition

Soil samples are acquired with CHIMRA’s clam-shell scoop mechanism, which can collect loose soil material from depths of up to 3.5 cm. The scoop can also collect unconsolidated samples from rover wheel-dug trenches, depending on the geometry of the trench, which might access material as deep as 20 cm below the original surface. This video shows some early scoop testing:

Step 2: Sample processing and HandlingSample Acquisition

The CHIMRA is a device that sieves and portions the samples from the scoop and the drill which are then distributed to the analytical instruments, SAM and CheMin. Various chambers and labyrinths within the mechanism are used to sort and sieve the drilled rock or scooped soil material.