Crater and rock hazard modeling for Mars landing
This paper describes various models made of Mars' topography that were used to help understand the engineering design trades involved in designing a Mars lander.
Mars↗
Engineering topics
Bernard, D. E.
Publications and source records attributed to Bernard, D. E..
Attitude and articulation control for CRAF/Cassini
The Comet Rendezvous/Asteroid Flyby (CRAF) and Cassini planetary missions provide exciting pointing and control challenges. The mission and science objectives, and an attitude and articulation control concept designed to meet these challenges, are described. CRAF/Cassini mission characteristics which drive pointing and control include: close range flybys of asteroids and icy satellites; Huygens probe guidance and communication; Saturn orbit insertion; comet rendezvous and orbit insertion; closed loop target tracking from a comet orbit perturbed by gas and dust pressure; fine spacecraft pointing for Titan radar mapping and Earth communications; requirements for autonomous failure detection; isolation; recovery; and 13.5 year lifetime. The philosophy and approach chosen to meet these challenges and the overall control architecture are addressed, including operational and autonomous safe modes. Critical functions are highlighted, such as charge coupled device imaging of stars and extended bodies which provide references for inertial and target referenced pointing respectively. Tradeoffs and rationale for the selection and location of sensors and actuators are reviewed.
Bell, C. E.↗
Passive nutation damping using large appendages with application to Galileo
The use of large appendages for passive nutation damping is analyzed, and an analytical expression is developed to predict the nutation damping time constants for a large class of spacecraft including Galileo. It is shown that the use of large appendages for nutation damping can significantly degrade spacecraft stability margins and that the final design of the nutation damper must represent a tradeoff between the damping performance and the stability margin for sufficiently large appendages. The time constant derivation is outlined and the Galileo design is presented, including tradeoffs.
Bernard, D. E.↗
Thermic diode performance characteristics and design manual
Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.
Bernard, D. E.↗