A top-on-down approach to the management of risk, cost, and time tradeoffs in aerospace systems

Numerous risk assessments of aerospace systems have been conducted to date, foremost of space transportation systems. Yet, despite all these assessments, major risk policy issues affecting core issues of the US space effort in the 1990s are neglected. Excessive emphasis is placed on risk reduction programs of specific systems (e.g., Space Shuttle) at exorbitant costs and schedule impacts, with insufficient planning for backup capabilities and their deployment. No planned allowance is made for "irreducible" risk; i.e., acceptance of risk factors in the prudent management of space systems capabilities. The issue is raised, whether due to the vast impact of single system failures, (e.g., Space Shuttle) US space transportation issues should allow for a substantial degree of "risk aversion." Such allowance should lead to the pursuit of mixed systems strategies, rather than reliance on single systems ("pure") strategies. These large scale impacts come about due to significant interdependencies of single failures in reusable launch systems, payloads, and missions.