SI-17 - Fail-safe Procedures

Implement the indicated fail-safe procedures when the indicated failures occur: [Assignment: organization-defined list of failure conditions and associated fail-safe procedures].


ID: SI-17
Enhancements: 

Space Segment Guidance

A fail-safe approach on a spacecraft means anticipating plausible fault modes—like partial loss of command link, radiation-induced memory corruption, or erroneous GPS updates—and predefining minimal, low-risk behaviors for each scenario. Many vehicles default to "safe mode," which shuts down non-essential subsystems and preserves only enough capability to re-establish ground communication or sustain life-critical functions (in manned settings). Some missions also implement "crippled mode," retaining a bit more functionality than safe mode, to isolate faulty modules while keeping some mission tasks alive. Designers must ensure these fallback states are carefully tested on the ground to avoid inadvertently worsening the situation—e.g., by resetting cryptographic keys at the wrong moment. Effective fail-safe logic confers a controlled, graceful degradation under duress, preserving the spacecraft's core viability so ground teams can attempt recovery or upload fresh directives.