Recent Results from the MicroMAS Global Environmental MonitoringNanosatellite Mission

Abstract:

The Micro-sized Microwave Atmospheric Satellite (MicroMAS) is a dual-spinning 3U CubeSat equipped with a
passive microwave radiometer that observes in nine channels near the 118.75-GHz oxygen absorption line.
MicroMAS is designed to observe convective thunderstorms, tropical cyclones, and hurricanes from a midinclination
orbit. The MicroMAS flight unit was developed by MIT Lincoln Laboratory and the MIT Space Systems
Laboratory and was launched to the International Space Station on July 13, 2014, and scheduled for an early
September deployment for a ~90-day mission. The payload is housed in the “lower” 1U of the dual-spinning 3U
CubeSat and mechanically rotated approximately once per second as the spacecraft orbits the Earth, resulting in a
cross-track scanned beam with a full-width half-max (FWHM) beamwidth of 2.4 degrees and an approximately 17-
km diameter footprint at nadir incidence from a nominal altitude of 400 km. The relatively low cost of MicroMAS
enables the deployment of a constellation of sensors, spaced equally around several orbit planes. A small fleet of
MicroMAS systems could yield high-resolution global temperature and water vapor profiles, as well as cloud
microphysical and precipitation parameters.
Significant advancements were made in the Assembly, Integration, and Test phase of the project development
lifecycle. The flight software and communications architecture was refined and tested in relevant lab facilities. The
power subsystem was modified to include additional required inhibits for the ISS launch. Hardware in the loop tests
as well as simulations of the attitude determination and control system (ADCS) were performed to validate the
unique dual-spinning, local vertical, local horizontal (LVLH) stabilized flight design. ADCS algorithms were tested
on a 3-axis air bearing and custom rig inside a 3-axis programmable Helmholtz cage. Finally, the integrated
spacecraft underwent a series of environmental tests in order to verify the results of thermal modeling analyses,
prove the performance of critical design components in relevant environmental conditions, and validate the software
and concept-of-operations developed for flight. We present these advancements, lessons-learned in developing a
science-oriented CubeSat system, and any available launch/on-orbit updates.