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Record Details

Record 49 of 45538
Enceladus Plume Density Modeling and Reconstruction for Cassini Attitude Control System
External Online Source: hdl:2014/45063
Author and Affiliation:
Sarani, Siamak(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Abstract: In 2005, Cassini detected jets composed mostly of water, spouting from a set of nearly parallel rifts in the crust of Enceladus, an icy moon of Saturn. During an Enceladus flyby, either reaction wheels or attitude control thrusters on the Cassini spacecraft are used to overcome the external torque imparted on Cassini due to Enceladus plume or jets, as well as to slew the spacecraft in order to meet the pointing needs of the on-board science instruments. If the estimated imparted torque is larger than it can be controlled by the reaction wheel control system, thrusters are used to control the spacecraft. Having an engineering model that can predict and simulate the external torque imparted on Cassini spacecraft due to the plume density during all projected low-altitude Enceladus flybys is important. Equally important is being able to reconstruct the plume density after each flyby in order to calibrate the model. This paper describes an engineering model of the Enceladus plume density, as a function of the flyby altitude, developed for the Cassini Attitude and Articulation Control Subsystem, and novel methodologies that use guidance, navigation, and control data to estimate the external torque imparted on the spacecraft due to the Enceladus plume and jets. The plume density is determined accordingly. The methodologies described have already been used to reconstruct the plume density for three low-altitude Enceladus flybys of Cassini in 2008 and will continue to be used on all remaining low-altitude Enceladus flybys in Cassini's extended missions.
Publication Date: Apr 25, 2010
Document ID:
20150008844
(Acquired May 28, 2015)
Subject Category: MECHANICAL ENGINEERING; SPACECRAFT DESIGN, TESTING AND PERFORMANCE
Document Type: Conference Paper
Meeting Information: SpaceOps 2010; 25-30 Apr. 2010; Huntsville, AL; United States
Meeting Sponsor: American Inst. of Aeronautics and Astronautics; Reston, VA, United States
Financial Sponsor: Jet Propulsion Lab., California Inst. of Tech.; Pasadena, CA, United States
Description: 29p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ENCELADUS; CASSINI MISSION; ATTITUDE CONTROL; FLYBY MISSIONS; PLUMES; TORQUE; REACTION WHEELS; SPACE PROBES; DENSITY (MASS/VOLUME); ICY SATELLITES; NAVIGATION; LOW ALTITUDE
Availability Source: Other Sources
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