Pyramid Comet Sampler (PyCoS)

Abstract

Future sample retuns missions from comets and small bodies require a sample acquisition system that can deal with a range of material strength and still satisfy a mimimum sample volume. To address these two requirements, Honeybee Robotics developed a piercing-style sampling system called Pyramid Comet Sampler (PyCoS). PyCoS falls into a family of sample capture systems that use piercing blades. Such systems could potentially include 2 or more blades. The ‘piercing blades’ systems are used every day as posthole diggers and tree spades. During our research we investigated a number of blade designs for 3 (Tetrahedron) and 4 blade (Pyramid) geometries. We designed and built experimental fixtures for a single shot and percussive approach of driving blades into subsurface. Test results demonstrate that it is possible to penetrate >10 cm depth in materials as strong as 4 MPa with energies per blade that can be generated by a Rosetta harpoon pyrotechnic device. Percussive systems, on the other hand, cannot penetrate 4 MPa materials with 2.5 J/blow hammer energy. Therefore, a single, high energy impact is the most robust approach to sample capture using piercing blades approach.