Candlewax Rockets: A Green Alternative for In-Space Propulsion

Space Exploration Initiative

Wax-based hybrid rocket propellants, including paraffin (common candlewax) and beeswax show promise as high-performing hybrid rocket propellants for chemical propulsion systems. Inherent safety and simplicity advantages and low cost (less than $4/kg) make waxes well-suited for widespread adoption for launch and in-space applications. Their benign nature compared to the toxicity and carcinogenicity which characterize currently-used propellants, such as hydrazine and nitrogen tetroxide, make paraffin an especially strong candidate for new entrants to the propulsion community.

The Space Enabled Research Group is focused on the use of paraffin and beeswax for small satellite missions. Specifically, we are investigating the centrifugal casting of waxes into annular geometries on Earth as well as in microgravity. The research group envisions the repurposing of wax thermal insulation at end of life for deorbit maneuvers. However, such a mission would require centrifugal casting of wax in orbit — a task which has never been done before. The microgravity environment is expected to reduce rotation rate demands for uniform casting, and the overall experimental investigation aims to quantify the differences between 1-g and microgravity centrifugal casting.

To date, two parabolic aircraft flights have been conducted, with one more upcoming.  Furthermore, three suborbital spaceflights are scheduled for 2021/22 alongside an ISS flight in order to test casting techniques in longer-term microgravity.  Image analysis of centrifugal casting tests have been employed to automate post-processing of solidification.