Development of commercial drag-augmentation systems for small satellites

Abstract

In the framework of the ESA CleanSat programme Cranfield University is developing a family of drag augmentation system (DAS) modules to enable small satellites in Low Earth Orbit (LEO) to comply with space debris mitigation requirements. There are currently two mature Cranfield DAS designs based on deployable Kapton sails using stored energy for deployment. One concept is Icarus and it is currently on-board the UK’s TechDemoSat-1 (launched 8 July 2014) and Carbonite-1 spacecraft (launched 10 July 2015). The second concept is the de-orbit mechanism (DOM) module, which is due to fly as technological demonstrator on the upcoming ESA ESEO mission. The key drivers used during the design process were: low cost, low mass, easy testability, safety, reliability, and avoidance of additional debris production. These drivers matched with top-level requirements, from a potential customers perspective (e.g.: satellite integrators), which were defined during the CleanSat study. Other relevant requirements for the DAS included demisability, performance (in terms of orbital decay), area-to-mass ratio, functionality, lifetime, and environment compatibility. This paper discusses the compliance of the Cranfield DAS designs with the identified requirements, and illustrates the scalability via application to several case study missions (500 kg and 200 kg LEO satellites). The two most challenging aspects to assess were compliance with the lifetime required for storage on ground and pre-deployment on orbit, and the effect of the orbital environment (radiation, ATOX, debris) on the sail. The study has provided useful input to explore new concepts based on the heritage designs; these concepts are evolutions of the DOM unit and hybrid designs. The hybrid design combines aspects of the Icarus and the DOM concepts to reduce the limitations of the respective individual devices and improve scalability, adaptability and manufacturability. In addition, this work is helping to achieve commercial readiness for the technology. This will enable development of a commercial DAS offering that will be an attractive solution for small satellite integrators, allowing them to meet debris mitigation requirements.