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Record Details

Record 47 of 45414
Estimation and Modeling of Enceladus Plume Jet Density Using Reaction Wheel Control Data
External Online Source: hdl:2014/45151
Author and Affiliation:
Lee, Allan Y.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Wang, Eric K.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Pilinski, Emily B.(Colorado Univ., Boulder, CO, United States)
Macala, Glenn A.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Feldman, Antonette(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Abstract: The Cassini spacecraft was launched on October 15, 1997 by a Titan 4B launch vehicle. After an interplanetary cruise of almost seven years, it arrived at Saturn on June 30, 2004. In 2005, Cassini completed three flybys of Enceladus, a small, icy satellite of Saturn. Observations made during these flybys confirmed the existence of a water vapor plume in the south polar region of Enceladus. Five additional low-altitude flybys of Enceladus were successfully executed in 2008-9 to better characterize these watery plumes. The first of these flybys was the 50-km Enceladus-3 (E3) flyby executed on March 12, 2008. During the E3 flyby, the spacecraft attitude was controlled by a set of three reaction wheels. During the flyby, multiple plume jets imparted disturbance torque on the spacecraft resulting in small but visible attitude control errors. Using the known and unique transfer function between the disturbance torque and the attitude control error, the collected attitude control error telemetry could be used to estimate the disturbance torque. The effectiveness of this methodology is confirmed using the E3 telemetry data. Given good estimates of spacecraft's projected area, center of pressure location, and spacecraft velocity, the time history of the Enceladus plume density is reconstructed accordingly. The 1-sigma uncertainty of the estimated density is 7.7%. Next, we modeled the density due to each plume jet as a function of both the radial and angular distances of the spacecraft from the plume source. We also conjecture that the total plume density experienced by the spacecraft is the sum of the component plume densities. By comparing the time history of the reconstructed E3 plume density with that predicted by the plume model, values of the plume model parameters are determined. Results obtained are compared with those determined by other Cassini science instruments.
Publication Date: Aug 02, 2010
Document ID:
20150008931
(Acquired May 29, 2015)
Subject Category: LUNAR AND PLANETARY SCIENCE AND EXPLORATION; MECHANICAL ENGINEERING; SPACE COMMUNICATIONS, SPACECRAFT COMMUNICATIONS, COMMAND AND TRACKING; ASTRODYNAMICS
Document Type: Conference Paper
Publication Information: (SEE 20150008903; 20150008904)
Meeting Information: AIAA Guidance, Navigation, and Control Conference 2010; 2-5 Aug. 2010; Toronto, ON; Canada
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
Organization Source: Jet Propulsion Lab., California Inst. of Tech.; Pasadena, CA, United States
Description: 30p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ESTIMATING; DYNAMIC MODELS; ENCELADUS; PLUMES; REACTION WHEELS; CONTROL DATA (COMPUTERS); PARTICLE DENSITY (CONCENTRATION); VAPOR JETS; CASSINI MISSION; TITAN 4B LAUNCH VEHICLE; SATURN (PLANET); FLYBY MISSIONS; ATTITUDE CONTROL; TELEMETRY; INTERPLANETARY FLIGHT; INTERPLANETARY NAVIGATION; GEYSERS; SPACECRAFT CONFIGURATIONS; SPACECRAFT DESIGN; ATTITUDE (INCLINATION); INSTRUMENT ERRORS; MATRICES (MATHEMATICS); ANGULAR MOMENTUM; SPACECRAFT TRAJECTORIES
Availability Source: Other Sources
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