Advanced concepts for launch vehicle control

The objective of the advanced launch system (ALS) program is to develop a family of launch vehicles which provides a substantial improvement in reliability, operability, and economy over existing systems. This requires that autopilot design and verification procedures be of minimum sensitivity to recurring costs while providing adequate, but not necessarily optimal, vehicle performance. One approach to accomplishing this task, namely, the utilization of advanced control design and analysis techniques, is considered. It is shown that the techniques, which represent a cross-section of developments in control theory, attempt to solve the ALS control problem in one of two ways: given increased knowledge of the launch vehicle and its environment, through greater model fidelity and additional sensor data; and autopilot design in the presence of quantified model/disturbance uncertainties and less stringent sensing requirements. It is concluded that the methods are promising and cost effective     

A study of on-orbit spacecraft failures

Even though spacecraft are carefully designed and tested to meet their mission lifetime, many suffer unrecoverable on-orbit failures very early. Other spacecraft, despite severe failures, are able to exceed their expected lifetime when effective failure recovery procedures are applied. In 2005, a study of on-orbit spacecraft failures was undertaken which resulted in identifying 156 failures occurring from 1980 to 2005 on civil and military spacecraft. These failures were analyzed to compare different spacecraft subsystems and estimate their impact on the mission. Although there is no perfect system that could prevent any failure, the lessons learned from the past years show that adequate testing, redundancy and flexibility are the keys to a reliable spacecraft failure recovery system.