Nanosatellites: Using CubeSats as a platform for technology demonstrations for Earth observing and astronomical instrumentation. Focus areas include nanosatellite and ground communication systems and evolution from single CubeSats into clusters and constellations. Currently, Prof. Cahoy is leading the bus and subsystem development of the Microsized Microwave Atmospheric Satellite (MicroMAS), a 3U dual-spinning CubeSat. The 2U bus will support a scanning 1U microwave radiometer payload built by MIT Lincoln Laboratory. Integration and test is expected to be complete by Summer 2013. MicroMAS has been selected for a NASA Educational Launch of Nanosatellites launch opportunity and is awaiting manifest.
Prof. Cahoy supported the MIT student team entry in the University Nanosatellite Program Competition 7 from 2011-2013, sponsored by the Air Force Office of Sponsored Research. The goal of the team’s ESPA-class student microsatellite, the Trapped Energetic Radiation Satellite (TERSat) is to use very low frequency (VLF) electromagnetic radiation in LEO to interact with the charged particles trapped by Earth’s magnetic field in the Van Allen Radiation Belts. The 5-meter TERSat VLF antenna consists of two 2.5 meter deployable antennas. Characterization of one of the 2.5 m antennas during deployment in microgravity was selected for a 2013 NASA parabolic flight opportunity.
In addition, Prof. Cahoy is collaborating with Aurora Flight Sciences on the development of a cluster of CubeSats for distributed radio remote sensing. Prof. Cahoy is also developing a CubeSat wavefront control technology demonstration payload called the Deformable Mirror Demonstration in collaboration with several others in the astronomy community.
Wavefront Control Systems: Developing high-actuator count MEMS deformable mirror systems for high contrast and high dynamic range imaging for both defense and scientific applications in the Wavefront Control Laboratory. Using high-actuator count MEMS deformable mirrors on space telescopes equipped with coronagraphs will enable future direct imaging of Earth-like exoplanets. Direct imaging of Earth-like exoplanets yield spectra that contain information about the composition and abundances of gases in the exoplanet atmospheres. These spectra can be used to infer whether or not there is life on Earth-like exoplanets. We develop and test wavefront sensing, control, and reconstruction algorithms as well as design, build, and test the performance of these optical systems. Related interests include use of deformable mirrors and other spatial light modulators for free space optical communication.
Space Environment: Understanding how both spacecraft and planetary atmospheres are affected by the variable influx of highly energetic particles from the Sun and from galactic sources. In addition to the everyday hazards of energetic particles trapped by Earth’s magnetic field in the Van Allen Radiation belts, solar storms and the effects of weapons at orbital altitudes produce increased radiation fluxes that disrupt and damage valuable commercial, defense, and scientific satellites. Gaining access to commercial, defense, and scientific spacecraft telemetry and anomaly databases and correlating these data with space weather sensor observations provides insight on how to predict and prepare for severe space weather. These data also provide an opportunity to investigate the sensitivity of different standard spacecraft components (such as power amplifiers, solar arrays, and photodetectors) to energetic particle fluxes, and how observations of space weather events made with standard components can augment observations made with dedicated space weather instruments. Spacecraft radio systems can also be used to measure atmospheric and ionospheric profiles using a technique called radio occultation. Ionospheric profiles can measure the effect of solar activity on the charged particles in planetary upper atmospheres. Atmospheric profiles are of temperature and pressure, and contribute to studies of planetary climate and weather. Developing multi-frequency radio occultation systems that can provide high vertical resolution profiles of humidity and concentrations of other atmospheric species would make valuable contributions to weather and climate models. Prof. Cahoy’s work on using geostationary communications satellites as space weather sensors was selected by the Air Force Office of Sponsored Research for a 2013 Young Investigator grant.