Boswell Technologies and the Space Plasma Power and Propulsion group at the Research School of Physics at the Australian National University (ANU) have successfully conducted a series of in-orbit tests of the Bogong Thruster.
The Bogong thruster is a novel cold gas thruster that uses solid naphthalene as a
propellent. Naphthalene is a green propellant and is inherently safe as it does
not need to be pressurised and is non-toxic. Naphthalene is the simplest of
the Polycyclic Aromatic Hydrocarbons which have been estimated to contain 20% of all the carbon in the universe).
For thrust, when Naphthalene is heated to a temperature similar to that of hot water in a cup of tea it sublimates and becomes a vapour. When this vapour expands through a nozzle it creates thrust in space that pushes the satellite. Due to its small electrical power requirements, it is ideal for manoeuvring small satellites into precise orbits and attitudes.
In-orbit testing was successfully completed in November 2023 using one satellite in the Skyraft-3 constellation, launched in mid 2023. The expected level of performance was demonstrated in-obit when the thruster gas valve was opened following validation of nozzle heating and naphthalene flow. Using only a few watts of electrical power to heat the naphthalene to 30 degrees Celsius, a significant change in the attitude rate and pointing was achieved using an estimated thrust of only 0.1 milliNewtons!
This achievement marks more than one first:
• Australian first cold gas thruster, conceived, designed, fabricated and tested in Australia to be successfully tested operating as expected in orbit
• World First use of a clean green propellent, Naphthalene thruster in orbit
Why Bogong, you ask
Controlled variable thrust ranging from 0 to 2 milliNewtons measured in our large space simulation vacuum system WOMBAT using a calibrated thrust balance.
The solid propellent (naphthalene) allows a Total Impulse of around 400 Newtonseconds for a 2 U Cubesat sized package. This means that at maximum thrust of 2 milliNewtons, the thruster will operate for about 60 hours.
very low power requirements of only a few Watts including all the control and interface electronics, so no requirement for large solar panels that increase drag significantly and decrease lifetime in orbit
few moving parts means high reliability
a very attractive price for a complete package