Determining Atmospheric-Density Profile of Titan
- Sarani, Siamak
- September 2010.
- Physical Description:
- 1 electronic document
- Restrictions on Access:
- Unclassified, Unlimited, Publicly available.
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- A method was developed for measuring the atmospheric density of Titan, the largest moon of Saturn, to create an accurate density profile as a function of altitude. This will allow mission planners to select safe flyby altitudes, and for navigation engineers to accurately predict the delta-v associated with those flybys. The spacecraft angular rate vector profile as a function of time is collected via telemetry from the onboard attitude estimator once every 2 seconds. The telemetry for thruster times, as a function of time, for eight Reaction Control System (RCS) thrusters is gathered, once a second, from the Propulsion Manager algorithm of the Cassini onboard attitude-control flight software. Using these data, the ground software computes the angular momentum vector profile and the per-axis external torque as a function of time imparted from the spacecraft only due to the atmospheric drag. The software can then determine the Titan atmospheric density profile as a function of time and altitude with the known values of spacecraft center of mass, the Titan-relative range and velocity data, the projected area, and the aerocenter, along with the estimated drag coefficient in a free molecular flow field.
- Other Subject(s):
- NASA Technical Reports Server (NTRS) Collection.
- Document ID: 20100033554.
NASA Tech Briefs, September 2010; 29.
- Copyright, Distribution under U.S. Government purpose rights.
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