This is a short term (less than one-year) effort to develop and implement an accurate operational attitude determination algorithm for the NSF Dynamic Ionosphere CubeSat Experiment (DICE) space weather mission. It will support the development of required software modules as well as continued operation of the two DICE satellites. Completion of the software modules will result in corrected calibrated electron density and temperature data from the Langmuir Probes onboard the satellites. More importantly, it will also enable an operational capability to retrieve the satellite attitude information so that both satellites can be reliably steered into the appropriate orientation for the E-field booms to be successfully deployed. This, in turn, will enable E-field measurements to be obtained, and the full science mission to be completed.
The tasks will be carried out as a collaborative effort between scientists and engineers at Utah State University (USU), Atmospheric & Space Tech Research Associates, and Embry-Riddle Aeronautical University (ERAU). The project will promote education and learning by involving students at USU and ERAU in both the satellite operations and data analysis tasks.
The Dynamic Ionosphere Cubesat Experiment (DICE) is one of the first NSF Cubesat missions to be selected and flown. The DICE project consists of two CubeSats, weighing less than 2.2 kg each, which were launched into a highly eccentric low Earth orbit on October 28, 2011. Together the DICE CubeSats measure gradients of electric fields and electron densities in the ionosphere. The main science goal of the DICE project is to study the causes of storm enhanced densities (SED), which is a major space weather disturbance and concern.
The "Dynamic Ionosphere CubeSat Experiment" or "DICE" mission led by Atmospheric & Space Technology Research Associates (ASTRA) and Utah State University’s Space Dynamics Laboratory (USU/SDL) is one of several missions that have been flown or are currently in development under NSF’s CubeSat-based Science Mission for Space Weather and Atmospheric Research program. DICE consists of two identical "CubeSats " launched on October 27, 2011 as secondary payloads from a Delta II rocket with the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) as the prime payload. After NPP was placed into its sun synchronous polar orbit the upper stage of the Delta II was restarted and DICE spacecraft were released into an 809 to 457 km at 102° inclination with one satellite chasing the other. Both satellites are expected to remain on orbit for about 15 years and the functional life of the spacecraft is expected to be limited by the cycle life of the batteries, ~3 years. The scientific purpose of the mission is to study the formation and evolution of geomagnetic storm enhanced density features that occur in the Earth’s Ionosphere. Each CubeSat has three science instruments, a Langmuir Probe (DCP) to measure in-situ ionospheric plasma densities, an Electric Field Probe (EFP) to measure DC and AC electric fields and a Three Axis Magnetometer (TAM). Figure 1 illustrates the DICE spacecraft and instrumentation configuration. Each of the two DICE spacecraft is identical in design and function, and both conform to a 1.5U CubeSat form factor (10x10x15 cm). The four EFP booms each extend 5 m from the spacecraft with spheres on the ends of the booms. The four shorter booms on the bottom-side of the spacecraft comprise the UHF communications turnstile antenna and are 0.2 m in length. The UHF booms also provide balance for the controlled spin of the spacecraft. The DCP sensor spheres are supported on the top and bottom of the spacecraft by extending scissor booms that extend 8 cm away from the spacecraft. The electronics for the EFP and DCP are housed in the spacecraft on the science board. Through this award the operations of the DICE spacecraft were extended allowing the mission to collect additional scientific data. A coordinated observational campaign was conducted in conjunction with ground-based radar at Millstone Hill. During this campaign a strong geomagnetic storm fortuitously occurred on March 17, 2013 allowing the mission to complete one of its primary scientific objectives. The spacecraft were able to observe geomagnetic storm enhanced density features in the Earth’s Ionosphere. The recorded telemetry signals from the entire DICE mission was able to be reprocessed under this award resulting in a more than doubling of the recovered data from the spacecraft. Significant progress has been made on correcting the time stamping of scientific data in the archive database due to spacecraft resets and upsets. Progress has been made in processing the Langmuir probe and magnetometer data. Unfortunately the electric field probes on the DICE spacecraft could not be deployed due to problems controlling the attitude and the deterioration of the spacecraft due to on orbit age.
