CubeSail (UltraSail)

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Mission typeTechnology: solar sail propulsion
OperatorNASA / University of Illinois
Spacecraft properties
Spacecraft type1.5 U CubeSat x2
ManufacturerUniversity of Illinois
Launch mass~ 3 kg
Start of mission
Launch date16 December 2018 [1]
Launch siteRocket Lab LC-1
ContractorRocket Lab
Orbital parameters
Reference systemGeocentric)
RegimeLow Earth

CubeSail mission is a low-cost spacecraft propulsion demonstration using two identical 1.5U CubeSat satellites to deploy a 260 m-long, 20 m2 solar sail ribbon between them. This mission is a first in a series of increasingly complex demonstrations leading up to a fullscale UltraSail heliogyro by the University of Illinois and CU Aerospace.


Solar sail types. A heliogyro could have dozens of blades

The University of Illinois together with CU Aerospace designed this mission to demonstrate deployment and to measure the thrust on a 7.7 cm × 250 m membrane (about 20 m2) made of aluminized mylar. The membrane was deployed between two 1.5U CubeSats that separated from each other in low Earth orbit. It is intended as a first step towards the development of a larger (1,600 kg[2]) solar sail concept called UltraSail intended for interplanetary and interstellar missions.[3] This last consists of multiple CubeSail-like structures that extend kilometers long film blades to ultimately form a heliogyro. Each sail blade would be as long as 5 kilometres (3.1 mi).[2] In the UltraSail version, the spacecraft spins around a central hub to flatten the blades by centrifugal force, supported by tip-CubeSats. For the kilometre long blades' stability, this requires a rotational period of 1 – 2 hours so they overcome the solar pressure force by 3 to 5 times. Each blade is a thin polyimide film coated with ripstop.[2] The blades provide propulsion by radiation pressure exerted by sunlight.

The second mission of this project is called I-Sail, proposed to be launched in 2022, and it consists of a 25 kg (55 lb) spacecraft with bilateral blades with a total sail area of 2,500 m2.[4] It will demonstrate thrust levels many times those of ion thrusters used for deep space missions and perform an Earth gravity escape.[4] Several science objectives are being assessed as secondary objectives.[4]


Artist's concept of UlraSail. Each blade has a width of 5 – 10 m and deployed to a blade length up to 5 km with a total 100,000 m2 of sail area.[5] Blade control is enabled with a satellite (tipsat) attached to each blade tip.

UltraSail is a proposed type of robotic spacecraft that uses solar radiation for propulsion. It builds upon the Heliogyro concept by Richard H. MacNeal, published in 1971,[6][7][5] and consists of multiple rotating blades attached to a central hub. Blade material -which is the solar sail- is mounted on multiple reels, each with a width of 5 – 10 m, and deployed to a blade length up to 5 km (3.1 mi) for a total 100,000 m2 of sail area.[5][8]

Although the Heliogyro design has no mass advantage over a square sail, it remains attractive because the method of deploying large sail blades is simpler than a strut-based design.[9] Blade stiffness is achieved by spinning the spacecraft (centrifugal force) with rotational axis generally pointing at the Sun.


The spacecraft's attitude (orientation), and therefore thrust direction, is controlled by changing the cyclic and collective blade pitch similar to a helicopter, but in this case blade control is initiated by small controllable mini-satellites (tipsat) at the tip of each blade.[2][10] The tipsat mass provides a stabilizing centrifugal force on the blade while in rotation. Each tipsat would be a 5-meter long carbon-fiber structure with a total mass of 50 kg, including avionics and 20 kg propellant (catalyzed nitrous oxide (N2O) and cold gas).[2] Alternatively, the tipsats could be propelled with electric microthrusters to control blade pitch.[11]

The maximum expected thrust force due to solar pressure is equivalent to 400 kW ion thruster systems used for comparable deep space missions.[11]


CubeSail was launched on an Electron launch vehicle on December 16, 2018 from New Zealand.[1][12] It was selected in 2012 by NASA to be launched as part of the ELaNa program.[13][14] Re-orientation of the CubeSats will cause the sail to undergo aerodynamic drag in the upper atmosphere for its disposal.

See also[edit]

Other solar sail spacecrat
  • IKAROS, a Japanese solar sail, launched in May 2010
  • LightSail, a controlled solar sail CubeSat to launch in 2019
  • NanoSail-D2, the successor to NanoSail-D, launched in November 2010
  • Near-Earth Asteroid Scout, a solar sail CubeSat planned to launch in 2019
  • Sunjammer, a solar sail that was cancelled before launch in 2014


  1. ^ a b Small Satellite Design and Testing Laboratory - CubeSail. University of Illinois. 2018.
  2. ^ a b c d e Initial development of the CubeSail UltraSail spacecraft. R. L. Burton, J. K. Laystrom-Woodard, G. F. Benavides, D. L. Carroll, V. L. Coverstone, G. R. Swenson, A. Pukniel, A. Ghosh, and A. D. Moctezuma. 27 August 2014.
  3. ^ NASA to Launch Two Small AE Satellites. Aerospace Illinois. 22 February 2012.
  4. ^ a b c I-Sail: 2500-Square-Meter Solar Sail Prototype Demonstrator. NASA SBIR 2017 Solicitation. 19 April 2017.
  5. ^ a b c Initial Development of the CubeSail/UltraSail Spacecraft. R. L. Burton, J. K. Laystrom-Woodard, G. F. Benavides, D. L. Carroll, V. L. Coverstone, G. R. Swenson, A. Pukniel, A. Ghosh, and A. D. Moctezuma. (2010)
  6. ^ MacNeal R. H., "Structural Dynamics of the Heliogyro", NASA-CR-1745A, 1971.
  7. ^ Burton, R. L., Coverstone, V. L., Hargens-Rysanek, J., Ertmer, K. M., and Botter, T., "Ultrasail-Ultra-Lightweight Solar Sail Concept," 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference&Exhibit, AIAA Paper 2005-4117, 2005.
  8. ^ CubeSail Homesite. CU Aerospace. Accessed on 30 December 2018.
  9. ^ "Design & Construction". NASA JPL. Archived from the original on 2005-03-11.
  10. ^ Design Concept for a Solar Sail with Individually Controllable Elements. (PDF) Tong Luo, Ming Xu, and Qingyu Qu. Journal of Spacecraft and Rockets. 2017. doi:10.2514/1.A33775
  11. ^ a b UltraSail. (PDF) R. Burton, and G. Benavides. 2003.
  12. ^ Pietrobon, Steven. "New Zealand Launch Record (2009 to present)". Retrieved 14 August 2017.
  13. ^ CubeSail]. Gunter's Space Page. 2017
  14. ^ CubeSat Launch Initiative. NASA. Upcoming ELaNa CubeSat Launches. 2018.