Session
Technical Session I: Advanced Technologies I
Abstract
Existing and expected debris mitigation regulations require LEO spacecraft to deorbit within 25 years. Given typical spacecraft ballistic coefficients, this places an upper limit of perigee of around 600 km altitude for nanosatellites such as CubeSats. Also with operational nanosatellite constellations being deployed in the coming years there is an increased need to remove small spacecraft from LEO orbits much faster to ensure that defunct satellites can be replaced within the constellation with new satellites. Practical deployable drag systems being developed as products can lower the ballistic coefficient sufficiently to allow perigee up to 800 km altitude, however this still rules out many launches above that altitude for CubeSats and MicroSats that ride as secondary payloads. There is also the problem that a drag system does not reduce total intersected time-area product, thus debris impact probability is not reduced even if the lifetime requirement is met. This paper provides an overview of a recently developed deorbit system using a CubeSat sized solid rocket motor that was successfully tested in February 2013. The system is adopted from technology applied for European launch vehicle igniters, available at the development partners. It has sufficient propulsive capability to lower the perigee of a 3-unit CubeSat from a 1000 km altitude circular orbit to comply with the 25 year maximum orbit lifetime. Test results will be presented for the deorbit system, generating around 180 N thrust and 590 Ns total impulse at atmospheric pressure. Furthermore the challenges and solutions of implementing such a system inside a nanosatellite mission (both technical, programmatic and legal) will be addressed. All thrusters have an off-axis thrust component that causes the spacecraft attitude to be unstable when thrust is applied. Analysis will be presented showing that sufficient gyroscopic stiffness is achieved at reasonable spin rates to maintain stability of a 3-unit CubeSat in a long-axis spin. Attitude control algorithms were tested in simulation to demonstrate that the spin rate and pointing accuracy can be achieved using only traditional CubeSat magnetic sensors and actuators.
Presentation Slides
Nanosatellite Deorbit Motor
Existing and expected debris mitigation regulations require LEO spacecraft to deorbit within 25 years. Given typical spacecraft ballistic coefficients, this places an upper limit of perigee of around 600 km altitude for nanosatellites such as CubeSats. Also with operational nanosatellite constellations being deployed in the coming years there is an increased need to remove small spacecraft from LEO orbits much faster to ensure that defunct satellites can be replaced within the constellation with new satellites. Practical deployable drag systems being developed as products can lower the ballistic coefficient sufficiently to allow perigee up to 800 km altitude, however this still rules out many launches above that altitude for CubeSats and MicroSats that ride as secondary payloads. There is also the problem that a drag system does not reduce total intersected time-area product, thus debris impact probability is not reduced even if the lifetime requirement is met. This paper provides an overview of a recently developed deorbit system using a CubeSat sized solid rocket motor that was successfully tested in February 2013. The system is adopted from technology applied for European launch vehicle igniters, available at the development partners. It has sufficient propulsive capability to lower the perigee of a 3-unit CubeSat from a 1000 km altitude circular orbit to comply with the 25 year maximum orbit lifetime. Test results will be presented for the deorbit system, generating around 180 N thrust and 590 Ns total impulse at atmospheric pressure. Furthermore the challenges and solutions of implementing such a system inside a nanosatellite mission (both technical, programmatic and legal) will be addressed. All thrusters have an off-axis thrust component that causes the spacecraft attitude to be unstable when thrust is applied. Analysis will be presented showing that sufficient gyroscopic stiffness is achieved at reasonable spin rates to maintain stability of a 3-unit CubeSat in a long-axis spin. Attitude control algorithms were tested in simulation to demonstrate that the spin rate and pointing accuracy can be achieved using only traditional CubeSat magnetic sensors and actuators.
