  The Hyperspectral Thermal Imager (HyTI) is a technology demonstration mission
that will obtain high spatial, spectral, and temporal resolution long-wave
infrared images of Earth's surface from a 6U cubesat. HyTI science requires
that the pointing accuracy of the optical axis shall not exceed 2.89 arcsec
over the 0.5 ms integration time due to microvibration effects (known as
jitter). Two sources of vibration are a cryocooler that is added to maintain
the detector at 68 K and three orthogonally placed reaction wheels that are a
part of the attitude control system. Both of these parts will introduce
vibrations that are propagated through to the satellite structure while
imaging. Typical methods of characterizing and measuring jitter involve complex
finite element methods and specialized equipment and setups. In this paper, we
describe a novel method of characterizing jitter for small satellite systems
that is low-cost and minimally modifies the subject's mass distribution. The
metrology instrument is comprised of a laser source, a small mirror mounted via
a 3D printed clamp to a jig, and a lateral effect position-sensing detector.
The position-sensing detector samples 1000 Hz and can measure displacements as
little as 0.15 arcsec at distances of one meter. This paper provides an
experimental procedure that incrementally analyzes vibratory sources to
establish causal relationships between sources and the vibratory modes they
create. We demonstrate the capabilities of this metrology system and testing
procedure on HyTI in the Hawaii Space Flight Lab's clean room. Results include
power spectral density plots that show fundamental and higher-order vibratory
modal frequencies. Results from metrology show that jitter from reaction wheels
meets HyTI system requirements within 3$\sigma$.
