Micro-particle impact detector experiment on MightySat I

The purpose of this report is to present the engineering design of a spaceborne Micro Particle Impact Detector (MPID) experiment. This experiment is manifested on a Phillips Laboratory spacecraft called MightySat I scheduled for launch in July 1998. A follow-on report will present the resulting particle impact data. The objective of this experiment is to measure direction and time of impact of spaceborne micron size particles with time of impact resolution of 0.1 seconds. The primary element in this experiment consists of two Metal-Oxide-Semiconductar (MOS) discharge capacitor detectors that discharge upon hypervelocity particle impact. The detectors were developed by Prof. J.J. Wortman from North Carolina State University. Each MOS particle detector is 3 in x 1-1/2 in and approximately 0.013 in thick. Each particle detector is bonded to a detector assembly that is in turn mechanically fastened to the external bottom plate of the MightySat 1 spacecraft. The detector assembly and associated electronics weigh less than 0.4 Ib and have a total impact detection area of 3.7 in(2). Each particle impact causes an impact event record to be stored in the spacecraft control unit for later downlink. Each impact event record will store time of impact and output from two coarse sun sensors. Data from the coarse sun sensors is used to help determine attitude of the spacecraft. The Phillips Laboratory MightySat I spacecraft, developed largely by CTA Space Systems in McLean, VA, designed for ejection from the Space Shuttle is a 6-sided composite structure, 20.5 in (height) by 19.0 in (diameter), 150 lb., and spin stabilized with 5 degree attitude knowledge. The MightySat I spacecraft is scheduled for orbit injection using a standard hitchhiker ejection system from space shuttle flight STS-88. (Ref. 1).