Harpoon characterisation, breadboarding and testing for Active Debris Removal

 A recently closed GSTP activity with Airbus Defence and Space has designed, manufactured and validated a projectile and deployer system capable of capture, detumble and deorbit a large, uncooperative debris object.

The models were then subjected to a rigorous test campaign validating key system functionalities, culminating in an End-to-End test campaign firing over a representative use-case distance at a target that represents a large debris object.

The activity built a chaser spacecraft that would release three deployers, each with its own projectile, fired using Nitrogen gas.

The first projectile would link the chaser with the target via a flexible tether that could be used to apply force to the target, stopping it from tumbling and then towing it to the re-entry trajectory. The second and third projectiles remain as back ups.

 The total projectile (seen above) mass is 2.20 kg, with a length of 950 mm and maximum diameter 115 mm. Following successful penetration of a target panel, force on the collar causes tear pins holding a sleeve over the barbs to fail. This ensures a spear-like profile to optimise penetration of targets, but allows deployable barbs to be included in the design with reduced probability of the projectile being pulled out of the target during detumbling.

An experimental test campaign was performed testing the functionality of the harpoon system by firing vertically at representative targets. The majority of these tests were performed within a vertical test rig over a range of 1.5 m or 2.5 m.  These tests characterised the accuracy of the projectile, finding it to be within acceptable limits for capturing large targets. The relationship between firing pressure and projectile velocity was investigated, and an optimum firing pressure of 12 bar was found, at which pressure the projectile deploys at 20-25 m/s. The functionality of the crushable zone within the head of the projectile was found to be capable of absorbing around 200 J of excess kinetic energy to prevent excess damage to the target or projectile. The barb deployment system was reliable and capable of capturing large satellite panels.

The test campaign concluded with a series of six full scale tests, which were conducted over 25 m. These tests required the projectile to be fired at significantly higher pressures than would be used in the use case, and this caused some issues, but the projectile was nonetheless validated to be capable of capturing a representatively sized panel at this distance.

 G61C-032MM closed in April 2019.