Simulation and Shuttle Hitchhiker validation of ...

JOURNAL OF SPACECRAFT AND ROCKETS Vol. 32, No. 5, September-October 1995

Simulation and Shuttle Hitchhiker Validation of Passive Satellite Aerostabilization

Downloaded by NASA LANGLEY RESEARCH CENTRE on September 6, 2017 | http://arc.aiaa.org | DOI: 10.2514/3.26688

Renjith R. Kumar,* Daniel D. Mazanek,* and Michael L. Heck* Analytical Mechanics Associates, Inc., Hampton, Virginia 23666 The Passive Aerodynamically Stabilized Magnetically Damped Satellite experiment will characterize and demonstrate passive aerodynamic stabilization and passive magnetic hysteresis damping of attitude rates. It is currently scheduled to be deployed on a Shuttle Hitchhiker flight. Although theoretically feasible, aerodynamically induced passive attitude stability represents a technology that has never been substantiated through actual flight experience. The two-week experiment will serve to validate overall performance predictions by the high-fidelity free-molecularflow simulation code developed at the Langley Research Center of NASA. The code can simulate with high fidelity the flight characteristics of a satellite in low Earth orbit. Aerostabilization, if proved, is highly desirable for future missions such as the Gravity and Magnetic Earth Surveyor. This paper describes the simulator, simulation results, and the Hitchhiker experiment in the context of the Gravity and Magnetic Earth Surveyor subsatellite aerostabilization requirements.

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Nomenclature = equatorial radius of Earth = induced flux density on permeable rod = saturation flux density of permeable rod = remanance of permeable rod = area of ith surface element = aerodynamic force vector on the ith surface element = elemental mass of incoming air molecules = solar force vector on the ith surface element = aerodynamic torque vector on the ith surface element = solar torque vector on the ith surface element = differential time element = empirically determined Gaussian coefficients = scalar magnetizing field along longitudinal axis of permeable rod = Earth's magnetic field vector at satellite location = coercive force of permeable rod = vector dipole moment induced on all rods = inward surface normal unit vector of ith surface element = Legendre functions (Schmidt-normalized) = solar pressure constant = scalar potential function of Earth's magnetic field = geocentric distance to satellite = position vector of center of area of ith surface element with respect to center of mass of satellite = unit vector along sun-satellite line of sight = magnetic damping torque vector = tangential unit vector of ith surface element = magnitude of velocity of incoming air molecules = velocity vector of incoming air molecules = unit velocity vector of incoming air molecules = mean velocity magnitude of diffusely reflected air molecules = velocity vector of diffused reflected components of air molecules = velocity vector of specularly reflected components of air molecules = angle between V and hf = cone angle of the satellite = coelevation of satellite

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