Micrometeoroid and Orbital Debris impact Damage Recording System

Damage from Micrometeoroid and Orbital Debris (MMOD) impacts poses a substantial risk for the loss of crew for the currently planned CEV missions to the International Space Station (ISS). The Columbia Space Shuttle accident in 2003 spurred an investigation that led to the requirement of an active impact monitoring system on the Shuttle Orbiter. The MMOD impact Damage Recording System (DRS) presents a reliable, mass- and power-efficient Thermal Protection System (TPS) impact detection system that can be readily integrated with manned and robotic spacecraft. Thus, the Crew Exploration Vehicle (CEV) is considering inclusion of active MMOD detection systems for monitoring damage to the backshell TPS. MMOD impact detection systems have been developed and flown on satellites and probes dating back to the 1960s. These technologies were designed primarily to understand and characterize the MMOD environment found in low earth orbit (LEO). The only impact monitoring system qualified for use on manned spacecraft is the wing leading edge impact detection system (WLE IDS). During Shuttle ascent, the WLE IDS monitors impacts due to insulating foam shed from the external fuel tank onto the WLE. The WLE is particularly vulnerable due to the high heating environment experienced during reentry. Ever-increasing accumulation of man-made debris is magnifying this threat to shuttle and other spacecrafts operating in LEO. Therefore, the development of on-orbit impact monitoring systems that aid in the mitigation of the threat to manned spacecraft is needed. This paper describes the development and testing of the DRS, a massand power-efficient wireless MMOD impact detection system designed for potential incorporation into the backshell of the CEV. The DRS utilizes wireless data acquisition via custom designed wireless nodes. The DRS wireless nodes determine MMOD impact damage by employing an Embedded Damage Recorder (EDR) sensor. A variety of EDR sensor designs were considered based upon different damage detection and TPS integration requirements. The DRS system design was recently tested at the University of Dayton Research Institute's hypervelocity impact range. During this test series, seven hypervelocity impacts were conducted using aluminum and nylon projectiles to simulate MMOD impacts to representative models of the CEV backshell TPS. The TPS models were fabricated in a flight-like configuration integrating the EDR sensor at the bondline. The DRS accurately indicated damage to the TPS models on all seven hypervelocity impact tests. These results have confirmed the feasibility of the DRS employing the EDR sensor as a viable MMOD impact sensing solution. Vehicle integration and further space environment testing remain critical steps in maturing this technology to flight qualification.