Reaction Wheel Disturbance Model Extraction Software

Period of Performance: 01/01/2008 - 12/31/2008


Phase 2 SBIR

Recipient Firm

Nightsky Systems, Inc.
3916 Lauriston Road
Raleigh, NC 27616
Principal Investigator
Firm POC


Reaction wheel mechanical noise is one of the largest sources of disturbance forcing on space-based observatories. Such noise arises from mass imbalance, bearing imperfections, and other sources. It takes the form of a number of discrete harmonics of the wheel speed, often also with a broadband noise component. Jitter problems can arise when harmonics sweep across observatory modes, and can be exacerbated by gyroscopically coupled spin-rate-dependent wheel structural modes that dynamically amplify the tonal and broadband disturbances. For a well-balanced wheel, higher harmonic forces can be on the same order as the fundamental, therefore when there is a jitter problem it can occur at very low wheel speed. These higher harmonics are generally less well-characterized than the fundamental.