PAGE CONTENTS
Objectives
A comprehensive investigation has been undertaken to study the effects that hypervelocity impact of micrometeoroids may have on GEO solar generators, in particular, whether and under which conditions permanent short-circuits may be induced by impact-generated plasma at the impact location. Highly instrumented experiments have been performed using a light-gas gun at Fraunhofer EMI and a plasma-dynamic accelerator at Technische Universität München. Astrium GmbH built solar array samples were set-up under representative electrical conditions for test. Unique test data has been acquired and the team succeeded in identifying the threshold conditions for impact-induced arcing and interpreting the underlying failure mechanism.
The objective of this project is to study and test the susceptibility of modern solar array designs to micrometeoroid and space debris impact. This includes:
- Establishing understanding of failure mechanisms and influencing factors,
- Experimentally simulating hypervelocity impacts under various conditions on operated test samples representing state-of-the-art solar arrays for high-power telecommunication platforms,
- Determine threshold conditions above which impact induced permanent short circuits may occur,
- Define appropriate design approaches to mitigate the effects of micrometeoroid impacts.
Picture: Impact plasma and temporary sustained discharges at a solar panel sample perforated from its rear side by a 1.6 mm particle impacting with 7.3 km/s.
Challenges
The key issue of this project was to evaluate the characteristics and effects of the impact generated plasma on an operating solar array and to quantify the related failure onset conditions.
The main challenges of the project were to experimentally reproduce impact induced failures on solar arrays on ground on the one hand. This required considering all aspects relevant to the failure process as well as their interactions. On the other hand, it was demanding to gain an experimental insight into the failure mechanism due to the temporally and spatially limitation of impact plasma related processes.
Plan
The contract was concluded at the beginning of 2010, the test campaigns accomplished at the end of 2011 and the final deliveries completed and the final review held in September 2012.
Within that time period the following work packages and accompanied milestone meetings have been completed:
WP2000: Literature/technology review & assessment of failure mechanisms
WP3000: Sample design and test plan definition
- Test plan review
WP4000: Sample manufacturing & test apparatus preparation
- Test readiness review
WP5000: Test execution
- Test review board
WP6000: Test results evaluation
- Final review
Current Status
The project has ended. All study objectives have been successfully achieved:
- More than 60 hypervelocity impact experiments have been performed under representative conditions.
- Comprehensive diagnostic data on impact plasma and failure processes have been acquired and evaluated.
- An understanding of impact induced failure mechanism has been established.
- Threshold conditions above which permanent failures may occur have been determined.
- The criticality of impact effects on GEO solar generators has been identified and quantified.
- Mitigation measures against impact effects have been proposed.