Cutout CAD models of the DICE CubeSat
Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats that were launched into an eccentric low Earth orbit on Oct. 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science-grade magnetometer to measure in-situ DC and AC magnetic fields.
Dr. Geoff Crawley from Astra was the mission PI. The satellites were built at Space Dynamics Laboratory under the guidance of program manager Chad Fish and Deputy PI Dr. Charles Swenson. Dr. Barjatya from SAIL was the Instrument PI on the Langmuir probes.
Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a “sensorsat” capable of comprehensive ionospheric diagnostics. The use of two identical sensorsat at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies, including miniaturized mechanisms and high-speed downlink communications.
A comprehensive paper on DICE mission has been published iin Space Science Reviews.
DICE is primarily an exploratory Space Weather mission. Several important research questions regarding Storm Enhanced Density (SED) were the focus of the DICE mission, specifically the physical processes responsible for the two features of SEDs: SED plume and SED bulge. But beyond the ambitious science, the CubeSat technology innovation in DICE was also state-of-the-art. This included a high-data-rate S-band radio, a total of 10 complex deployable booms, the first dual-constellation of satellites trying to do science and so on.
DICE had two 1.3 cm diameter gold-plated spherical Langmuir probes that were deployed from the top and bottom of the CubeSats on scissor booms. To avoid adverse spacecraft charging events, the probes were biased in the ion saturation region at -7 volts. The Langmuir probes were typically sampled at 35Hz but also had the capability to be sampled at 70Hz in "science mode." Deploying the two probes 180 degrees apart guaranteed that at least one of them would be out of the wake. SAIL has published a paper on complicated wakes around CubeSats in Journal of Spacecraft and Rockets.
The figure below shows three orbits of the two DICE CubeSats (named Yahtzee and Farkle) overlaid on each other. Farkle was following Yahtzee for 26 minutes in the same orbital plane. The plot shows in-situ observed ion density at the same physical location, 26 minutes apart in time. Measurements like this show the power of doing CubeSat constellations wherein is possible to do spatial and temporal measurements of plasma parameters.
