Coring Sample Acquisition Tool
- Wednesday, 01 August 2012
A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.
The SAT can be divided into four sub-elements termed the spindle/percussion assembly (SPA), magnetic chuck assembly (MCA), core bit assembly (CBA), and the core break-off assembly (CBO). The SPA is used to impart the necessary rotational degree of freedom to the CBA to clear cuttings and impart the required impact energy to facilitate rock fracture. The percussive nature of the tool is imparted through the use of an eccentric CAM/lever mechanism. The MCA is designed to actively release the CBA to the SHEC and in air (no load), and passively under large enough side loads, and in air (no load). The magnetic chuck uses two diametrically polarized rings (permanent magnet) stacked one on top of the other. A low-torque actuator is then used to engage or disengage the chuck by aligning or de-aligning the polarized ring poles. The CBA accepts the rotational degree of freedom from the SPA and is used to clear the rock cuttings using a two-lead flutecoring bit. The CBA also transfers the impacts of a striker inside the SPA to the rock being drilled. Furthermore, the coring bit shapes and defines the geometric constraints of the core sample.
Lastly, the CBO is housed inside the CBA and is used to create break-off and capture the core sample. It is actuated through the use of a torque nut that axially retracts an outer tube using an Acme thread. The outer tube has a series of ramps that drives a set of teeth into the shaped core, fracturing the base of the core and effectively capturing the core within a sample tube. The tool is designed to allow the captured core to be transferred out of the aft portion of the CBA and CBO without ever having to handle the core after capture.