Journal of The Astronautical Sciences 

About: Journal of The Astronautical Sciences is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Spacecraft & Computer science. It has an ISSN identifier of 0021-9142. Over the lifetime, 1111 publications have been published receiving 20246 citations.

Shuttle entry guidance

Abstract: This paper describes the design of the entry guidance for the Space Shuttle Orbiter. This guidance provides the steering commands for trajectory control from initial penetration of the earth's atmosphere until the terminal area guidance is activated at an earth-relative speed of 2500 fps. At this point, the Orbiter is at a distance of about 50 nmi from the runway threshold, and at an altitude of about 80,000 ft. The entry guidance design is based on an analytic solution of the equations of motion defining the drag acceleration profile that meets the terminal criteria of the entry flight while maintaining the flight within systems and operational constraints. Guidance commands, which are based on a control law that ensures damping of oscillatory type trajectory motion, are computed to steer the Orbiter to this drag acceleration profile.

Quaternion Attitude Estimation Using Vector Observations

Abstract: This paper contains a critical comparison of estimators minimizing Wahba’s loss function Some new results are presented for the QUaternion ESTimator (QUEST) and Estimators of the Optimal Quaternion (ESOQ and ESOQ2) to avoid the computational burden of sequential rotations in these algorithms None of these methods is as robust in principle as Davenport’s q method or the Singular Value Decomposition (SVD) method, which are significantly slower Robustness is only an issue for measurements with widely differing accuracies, so the fastest estimators, the modified ESOQ and ESOQ2, are well suited to sensors that track multiple stars with comparable accuracies More robust forms of ESOQ and ESOQ2 are developed that are intermediate in speed