SUSTAINABILITY IN AN AGE OF SPACE TRASH: ADAPTING ION THRUSTERS FOR USE ON CUBESATS

With the advent of commercial space launches for satellites, orbital space near earth is increasingly crowded. An estimated half million objects are being tracked by ground-based sensors. These objects include both operational and defunct satellites, discarded rocket stages from previous launches, and debris from former spacecraft. Simultaneously, small satellites, e.g., cubesats, have the potential to make basic space infrastructure such as communications and weather tracking far more accessible to institutions worldwide. Cubesats are small satellites composed of one or more modular units. With the number of objects, including cubesats, in orbit increasing, some way to address satellites at end-of-life is needed. End-of-life for satellites can involve moving the object to a so-called graveyard orbit or to de-orbit down towards earth to be incinerated in the atmosphere upon re-entry. This paper compares two methods for providing propulsion of cubesats at end-of-life, direct current electron bombardment (DC) and radiofrequency (RF) ion thrusters. These two types of ion thrusters are compared for both impact on spacecraft lifespan and on Δv or change in velocity delivered to a spacecraft. A three unit cubesat was modeled using CAD software Solidworks and exit velocity of plasma generated was modeled using ANSYS Fluent 2019 software. A 12% increase in Δv was calculated for the modeled RF as compared to the DC electron bombardment ion thruster and most importantly the Δv exceeded orbital velocity. This finding implies that RF ion thrusters can effectively de-orbit small cubesats allowing incineration upon reentry to earth’s atmosphere as an end-of-life option.