A proposed alternative design for the balloon- borne ground-sampling system described in the immediately preceding article would not rely on free fall to drive a harpoonlike sample-collecting device into the ground. Instead, the harpoon-like sample-collecting device would be a pyrotechnically driven, tethered projectile.

A Gun Aimed Downward From the Top of a Tripod would fire a tethered projectile into the ground to collect a sample when all three feet of the tripod simultaneously touch the ground.
The apparatus would include a tripod that would be tethered to the gondola. A gun for shooting the projectile into the ground would be mounted at the apex of the tripod (see figure). The gun would include an electronic trigger circuit, a chamber at the breech end containing a pyrotechnic charge, and a barrel. A sabot would be placed in the barrel just below the pyrotechnic charge, and the tethered projectile would be placed in the barrel just below the sabot. The tripod feet would be equipped with contact sensors connected to the trigger circuit.

In operation, the tripod would be lowered to the ground on its tether. Once contact with the ground was detected by the sensors on all three tripod feet, the trigger circuit would fire the pyrotechnic charge to drive the projectile into the ground. (Requiring contact among all three tripod feet and the ground would ensure that the projectile would be fired into the ground, rather than up toward the gondola or the balloon.) The tethered projectile would then be reeled back up to the gondola for analysis of the sample.

This work was done by Jack Jones, Wayne Zimmerman, Jiunn Jenq Wu, Mircea Badescu, and Stewart Sherrit of Caltech for NASA’s Jet Propulsion Laboratory. NPO-44445

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Tethered Pyrotechnic Apparatus for Acquiring a Ground Sample

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NASA Tech Briefs Magazine

This article first appeared in the August, 2009 issue of NASA Tech Briefs Magazine (Vol. 33 No. 8).

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Overview

The document outlines the development and testing of a Tethered Pyrotechnic Apparatus for acquiring ground samples from planetary surfaces, particularly in the context of missions to Titan, Mars, Venus, and other celestial bodies. Led by Principal Investigator Jack A. Jones and a team of co-investigators, the project aims to create a lightweight, efficient sample acquisition system that can be deployed from balloon platforms or spacecraft hovering above planetary surfaces.

The primary objectives of the project include measuring penetration energies for cryogenic ice and regolith, designing and testing a gravity-dropped harpoon sampling system, and developing a pyro-activated harpoon system capable of collecting at least 1 gram of surface material. The system is intended for use in various planetary exploration missions, including those targeting Mars' polar regions, Venus' surface, and sample return missions from comets and asteroids.

Key results from the project include successful measurements of penetration energies for sampling ice at different temperatures (260 K and 77 K) and moist surface sand. The team designed, fabricated, and tested a gravity-drop harpoon system that simulates dropping from a height of 100 meters above Titan's surface, as well as a pyro-activated harpoon system that effectively collects over 1 gram of cryogenic ice. Additionally, a tethered harpoon system was developed to allow rapid collection of surface samples, which can then be reeled back to the remote platform for analysis.

The document highlights the novelty of the tethered pyro harpoon system, which addresses the limitations of previous sampling methods, such as robotic arms and mechanical drills, that are not suitable for quick sampling from balloon platforms. The design includes a tripod that stabilizes the harpoon during deployment, ensuring accurate penetration into the surface material.

Overall, the Tethered Pyrotechnic Apparatus represents a significant advancement in planetary exploration technology, enabling efficient and effective sample collection from challenging environments. The results of this research have implications for future missions, enhancing our ability to analyze extraterrestrial materials and expand our understanding of other planetary bodies. For further inquiries, the document provides contact information for the Jet Propulsion Laboratory's Innovative Technology Assets Management.