The DiskSat: A Two-Dimensional Containerized Satellite (2021)

A key factor in the remarkable expansion of the CubeSat class of spacecraft over the past two decades is launch containerization. The container protects the launch vehicle and primary payload from issues that might arise from the CubeSat (which is essential for rideshare), and the standardized and highly-simplified launch interface reduces integration cost for the launch provider and development cost for the CubeSat builder. The downside of containerization is that the size of the contained satellites is rigidly limited. While there are available designs for larger dispensers and CubeSats, very few CubeSats larger than 6U have flown, and none have been larger than 16U. Future space missions will benefit from more power and RF aperture, beyond what can be provided by conventional CubeSats, even with complex deployables. We propose here the DiskSat, a containerized, large-aperture, quasi-two-dimensional satellite bus architecture.\nA representative DiskSat structure is a composite flat panel, one meter in diameter and 2.5 cm thick, to which components are affixed in a flat pattern within the panel. The volume of the representative DiskSat is almost 20 liters, comparable to a hypothetical 20U CubeSat, while the structural mass can be less than 2.5 kg. The surface area of a single disk face is substantially larger than the total surface area of any conventional CubeSat, supporting over 200 W of peak solar power without the complexity of deployables, thereby improving mission assurance and reducing vehicle cost. Alternatively, a single fixed deployable panel can ensure that the vehicle has over 100 W orbit-average power while maintaining nadir pointing in any beta angle.\nFor launch, multiple DiskSats are stacked in a fully-enclosed container/dispenser using a simple mechanical interface, and are released individually once in orbit. Stacking of 20 or more DiskSats is possible in small launch vehicles, making it ideal for building large constellations of small satellites in multiple discrete orbital planes. The 1-m-diameter DiskSat was developed with the Rocket Lab Electron in mind; the concept can be extended to larger diameters (1.2 m for the Virgin LauncherOne, for example), or to other flat shapes (square for an ESPA port, for example), and to greater thicknesses if the mission requires it.\nThe DiskSat concept was developed as a cost-effective solution for a LEO constellation that required significant power and RF aperture. Since then we have explored the utility of the bus architecture for a broad range of missions including Earth observation and space science, among others. One particularly useful feature of the DiskSat is the high power-to-mass ratio, enabling high-delta-v electric propulsion missions, including deep-space applications. Another feature is the ability to fly in a low-drag orientation which, in combination with electric propulsion for drag makeup, enables flight at very low altitudes in LEO.\nThis paper will detail the design of the DiskSat and its dispenser, will explore the range of missions enabled by the DiskSat, and will describe current development activities in support of a DiskSat demonstration flight.