Orbital Bias Determination for Accelerometers on Atmosphere Explorer Satellites.
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MASS
Pagination or Media Count:
An extensive amount of neutral density data has been obtained from the highly successful accelerometer experiments on the Atmosphere Explorer -C, -D, and -E satellites. The accelerometer is electrostatically suspended and force rebalanced. Ground calibration requires sufficient suspension force to operate in the earths 1g field. An important characteristic of the instrument is its null bias which is proportional to the suspension voltage. Null bias error is reduced when the instrument is in orbit by reducing the suspension force. For despun orbit data, accelerations due to bias must be separated from those due to drag for accurate density computation. In the elliptical orbit phase of the AE missions, bias values have been deduced from the sensor output obtained at altitudes where aerodynamic drag is negligible. Bias measurements obtained from all three satellites are summarized. A bias temperature coefficient is also calculated. Results in this report show that orbital values differ from a simple extrapolation of the ground calibration data. This difference must be known to obtain accurate density data above about 200 km. The orbital bias results are applied to improve the accuracy of despun orbit measurements made during both the elliptical and circular orbit phases of the AE mission. Methods of extending bias determination to circular orbit data are discussed. Author
- Test Facilities, Equipment and Methods
- Unmanned Spacecraft
- Spacecraft Trajectories and Reentry