Propellantless Propulsion

CUA has developed multiple solar and drag sail technologies. A major advantage of a “propellantless” solar sail is that the need for a relatively massive and expensive propulsive device is avoided. Drag sail technologies can also take advantage of propellantless solar sail technology at higher altitude and then ultimately utilize aerodynamic forces to drag a spacecraft down to burn up in the Earth’s atmosphere.

Advantages of sail technology include:

  • Propellantless propulsion – solar photons provide thrust
  • Solar sails enable very high payload mass fractions > 50%
  • Drag sails utilize aerodynamic forces for deorbiting
  • Attitude control systems can “tack” sail(s) to provide trajectory change


CUA designed and built CubeSail, a system of 2x1.5U CubeSat satellites which is highly scalable. This project was selected to receive NASA CubeSat Launch Initiative support from NASA’s Human Exploration and Operations Mission Directorate. CubeSail mission goals are successful sail deployment, attitude control, and deorbit. CubeSail was launched in Dec. 2018, but communication was never established. While the specific cause is uncertain, our best assessment is that the radios failed once in orbit. For more detailed information about CubeSail and its mission check out the CubeSail website.


CUA’s I-Sail concept is a 38 kg UltraSail demonstrator spacecraft with 3,800 m^2. I-Sail represents the next stage of risk reduction for the UltraSail technology prior to full-scale interplanetary development. A down-scaled version of the Heliostorm warning mission is recommended for the I-Sail demonstrator.


This technology represents a next-generation high-risk, high-payoff solar sail system for the launch, deployment, stabilization and control of very large (km^2 class) solar sails, enabling very high payload mass fractions for interplanetary and deep space spacecraft. UltraSail is an innovative, non-traditional approach to propulsion technology achieved by combining microsatellite propulsion and control systems with an innovative solar sail architecture using reel storage to achieve controllable sail areas approaching 1 km^2, sail subsystem areal densities < 5 g/m^2, and thrust levels many times those of ion thrusters used for comparable deep space missions.

CubeSail-D (DragSail)

CUA designed a system of 6U CubeSat concept called CubeSail-D, based upon CubeSail concepts, but with a focus on Low Earth Orbit (LEO) for deorbit (drag) capabilities. A unique feature of the CubeSail-D design is its ability to control the solar sail blade pitch and therefore enable deorbiting thrust from solar photon pressure, not just aerodynamic drag. This capability of CubeSail-D becomes progressively more important at higher altitudes and critical above 1000 km.

Related Publications
A. Pukniel, V. Coverstone, R. Burton, and D. L. Carroll, “The dynamics and control of the CubeSail mission: A solar sailing demonstration” 30 Jul. 2011, Journal of Advanced Space Research, Vol. 48, No., pp. 1902-1910, DOI 10.1016/j.asr.2011.07.014, (2011)
R. L. Burton, V. Coverstone, J. Hargens-Rysanek, K. Ertmer, T. Botter, G. F. Benavides, B. Woo, D. L. Carroll, P. Gierow, G. Farmer, and J.M. Cardin, “UltraSail - Ultra-Lightweight Solar Sail Concept” 10 Jul. 2005, 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Tucson, Arizona, 10-13 July 2005, Tucson, Arizona, Jul 10-13, 2005, AIAA Paper 2005-4117, Vol., No., pp., DOI n/a, (2005)