Nanosatellites for earth environmental monitoring: The MicroMAS project

Abstract

The Micro-sized Microwave Atmospheric Satellite (MicroMAS) is a dual-spinning 3U CubeSat equipped with a passive microwave spectrometer that observes nine channels near the 118.75-GHz oxygen absorption line. The focus of this MicroMAS mission (hereafter, MicroMAS-1) is to observe convective thunderstorms, tropical cyclones, and hurricanes from a near-equatorial orbit. The MicroMAS-1 flight unit is currently being developed by MIT Lincoln Laboratory, the MIT Space Systems Laboratory, and the MIT Department of Earth and Planetary Sciences for a 2014 launch to be provided by the NASA CubeSat Launch Initiative program. As a low cost platform, MicroMAS offers the potential to deploy multiple satellites than can provide near-continuous views of severe weather. The existing architecture of few, high-cost platforms, infrequently view the same earth area which can miss rapid changes in the strength and direction of evolving storms thus degrading forecast accuracy. The 3U CubeSat has dimensions of 10 x 10 x 34.05 cm 3 and a mass of approximately 4 kg. The payload is housed in the "lower" 1U of the dualspinning 3U CubeSat, and is mechanically rotated approximately once per second as the spacecraft orbits the Earth. The resulting cross-track scanned beam has a FWHM beam width of 2.4º, and has an approximately 20-km diameter footprint at nadir incidence from a nominal altitude of 500 km. Radiometric calibration is carried out using observations of cold space, the Earth's limb, and an internal noise diode that is weakly coupled through the RF front-end electronics. In addition to the dual-spinning CubeSat, a key technology development is the ultra-compact intermediate frequency processor (IFP) module for channelization, detection, and analog-to-digital conversion. The payload antenna system and RF front-end electronics are highly integrated, miniaturized, and optimized for low-power operation. To support the spinning radiometer payload, the structures subsystem incorporates a brushless DC zerocogging motor, an optical encoder and disk, a slip ring, and a motor controller. The attitude determination and control system (ADCS) utilizes reaction wheels, magnetorquers, Earth horizon sensors, peak power tracking, a magnetometer, and a gyroscope. The communications system operates at S-band using the Open System of Agile Ground Stations (OSAGS) with a 2.025-2.120 GHz uplink and 2.200-2.300 GHz downlink at 230 kbps. MicroMAS-1 uses a Pumpkin CubeSat Motherboard with a Microchip PIC24 microcontroller as the flight computer running Pumpkin's Salvo Real Time Operating System. Thermal management includes monitoring with thermistors, heating, and passive cooling. Power is generated using four double-sided deployable 3U solar panels and one 2U bodymounted panel with UTJ cells and an electrical power system (EPS) with 30 W-hr lithium polymer batteries from Clyde Space. Tests with the MicroMAS-1 Engineering Design Model (EDM) have resulted in modifications to the spinning assembly, stack and ADCS system and have informed the developm...

Subsystem support feasibility for formation flight measuring Bi-directional Reflectance

“…To account for noise in the context of fo rmation ADCS, analogous work on precise pointing control with all the above environments in a hardware-in-the-Ioop (HWIL) simulation was studied. Analysis reviewed included the SPHERES Program and GNC system development via MicroMAS [38] and ExoplanetSAT [33]. The reaction wheel stage of ExoplanetSat, both in simulation and HWIL verification on MIT's spherical air bearing testbed, has shown pointing precision at LEO within 40 arcsec [33] or 0.011 0 where the air bearing was able to closely track the commanded angular orientation [39], verifying the existing HWIL control simulation.…”

A CubeSat catalog design tool for a multi-agent architecture development framework

“…The second payload is the NanoCam C1U, which is a slightly larger camera. The third payload is both the NanoCam C1U and a hyperspectral millimeter-wave atmospheric sounder, such as that of the MicroMAS mission [14]. Furthermore, each of these payloads were input to the tool at two different orbits: LEO-400-polar-NA and LEO-600-polar- NA.…”

Payload characterization for CubeSat demonstration of MEMS deformable mirrors

“…Figure 4 shows an isometric view of this design. The design of the supporting bus is based on the components from the Microsized Microwave Atmospheric Satellite (MicroMAS) 29 , a 3U CubeSat designed and built by the MIT Space Systems Laboratory and MIT Lincoln Laboratory for a mid-2014 launch. The structure is custom-designed to accommodate cutouts, the payload, and interfaces with bus components.…”