MAGNETO: Mapping the Earth’s Magnetic Field at 300 km using COTS Sensors

In the nearly two decades that CubeSats have been in significant use, over 800 have been launched, and many more are under construction. They have gained popularity in the industry and are often the choice for most first-time small-satellite missions. The University of Southern California’s (USC) Space Engineering Research Center (SERC) has developed a 1.5U student-built science mission called Magneto. Magneto is USC’s fourth CubeSat mission, and it has the goal of mapping the Earth’s magnetic field in Low-Earth Orbit (LEO) using Commercial Off-The-Shelf (COTS) hardware, to determine the viability of using COTS sensors to decrease the mission cost by a hundred-fold from similar missions using dedicated science instruments, while offering similar levels of precision. The spacecraft, built in partnership with Omega Engineering, will utilize COTS sensors provided by Omega to measure the Earth’s magnetosphere. These will be deployed on carbon-fiber booms to minimize the spacecraft’s effect on the magnetic field measurements throughout the mission. To collect accurate magnetosphere measurements without the use of GPS or a star tracker, the team at SERC developed a novel method to acquire attitude updates using a single sun sensor. This new GNC methodology is able to obtain the spacecraft’s attitude while operating under an unknown rotation rate. The spacecraft obtains its position from the USC ground-station by finding the time of closest approach using the Doppler effect. Combining this data over multiple passes and using statistical analysis, the space craft position can be determined to within a few kilometers. The Magneto spacecraft was scheduled on the manifest for the inaugural launch of the Firefly Alpha vehicle as part of Firefly’s DREAM program, a STEM outreach effort to offer University and High School students a free launch opportunity to LEO. Due to the Covid-19 delays Magento’s delivery was moved to alternative opportunities in Fall of 2020 or Spring of 2021. This paper will describe the design of the CubeSat, its unique mechanisms that enable compacts to wage and deployment of antennas and magnetometers, and the novel GNC approach used to determine attitude and position throughout the orbit