The Ørsted Satellite Project

MAGNETIC FIELD DATA ANALYSIS OF 4 FREE-FLYER MAGNETOMETERS

Zheng, Y. (1), K.A. Lynch (1), M. Bohm (2)

1. Institute for the Study of Earth Oceans and Space, University of New Hampshire, Durham, NH03824, USA. Phone: 603 862 4368, Fax: 603 882 0311, E-mail: yzheng@hopper.unh.edu
2. Lockheed Martin Advanced Technology Center 3251 Hanover Street, Palo Alto, CA94304, USA.

Abstract. Four hockey-puck-sized free-flyer magnetometers were deployed as autonomous nanospacecraft from an auroral sounding rocket payload. Assuming that payloads had near-rigid body motion, the data analysis procedure was done for them using an in-flight calibration method. First, we use the method developed by P. Brauer and J. Merayo to orthogonalize the three sensor axes so that the coning and spining modulation in the total magnetic field are minimized. Second, we align the three sensor axes with the spin system axes by rotating through 3 Euler angles. Euler angles are found by minimizing the spin signatures in the spin-axis-component of the magnetic field and the transverse (relative to the spin axis) part of the magnetic field. Third, using the expression for the spin-axis-component from the model of rigid body motion, we fit coning parameters using linear regression. Then we fit the spin parameters from the two tranverse components. This was sun-sensor data constrained. The data can be then despun by using all the fitted parameters, and the three components in a B-L system are found. The data analysis results show approximately 50-100 nT oscillations in the data from the payloads, at the time when they entered the poleward edge of the auroral zone.