Synopsis
Here is a summary of the key points from the paper:
Overview
- Hypervelocity impacts from M/OD can lead to catastrophic failures of manned spacecraft through modes like gas leakage, cabin fracture, and spacecraft breakup.
- This paper develops methods to assess the risk of catastrophic failure modes using criteria like critical perforation diameter, critical crack length, and critical fragment size.
- Assessment modules were added to the Meteoroid and Orbital Debris Assessment and Optimization System Tools (MODAOST) software to enable efficient evaluation.
- The methods were demonstrated on a case study of a specific ultralarge manned spacecraft design.
Failure Modes and Criteria
- Astronaut Hypoxia: Gas leakage causes low pressure and oxygen, threatening astronaut survival. Critical perforation diameter is the size above which pressure drops below safe levels for emergency escape time.
- Cabin Fracture: Cracks can propagate and fracture the cabin. Critical crack length is when stress intensity exceeds material fracture toughness.
- Spacecraft Breakup: Total fragmentation of the vehicle. Critical fragment size model is used as the failure criterion.
Key Equations
- Perforation diameter and crack length equations for the stuffed Whipple shield were developed based on impact tests.
- Ballistic limit equations for the shield were also formulated.
- These feed into the failure criteria for the different modes.
Case Study
- Assessment methods were applied to an ultralarge manned spacecraft design with a 100 m3 cabin.
- Astronaut hypoxia was the most likely failure mode, with a probability of 0.159.
- The overall probability of no catastrophic failure was 0.9995, improved over previous PNP-based estimates.
- The new methods enable more accurate risk quantification to inform design and operations.
In summary, this paper presented an approach to assess catastrophic failure risks for manned spacecraft from M/OD impacts using physics-based criteria and efficient computational methods. The techniques were demonstrated on a case study spacecraft, identifying key failure likelihoods.
