CubeSail, designed by CU Aerospace and the University of Illinois, is a low-cost flight experiment based on the UltraSail concept.


CubeSail, designed by CU Aerospace (Champaign-Urbana Aerospace) and the University of Illinois, is a low-cost flight experiment based on the UltraSail concept. This experiment uses two CubeSat satellites to deploy a 20 sq. meter solar sail, which can play the same role as propellant on a conventional spacecraft.

A major advantage of a “propellantless” solar sail is that the need for a relatively massive and expensive propulsive device is avoided. CubeSail mission goals are successful sail deployment, attitude control, and deorbit.


It is with great regret that we are officially calling an early end to the CubeSail mission, notably before we were ever able to deploy the solar sail. Satellite beacons at the correct frequency were observed post-launch once on 18 Dec. 2018, but not with sufficient signal to noise ratio to demodulate the call sign in the beacons. No further communications were received from CubeSail. After more than 2 years of continued efforts to establish full communication with CubeSail, we sadly believe that the satellites have irrevocably failed without the possibility of resurrection. While it is uncertain the specific cause, our best assessment is that the radios failed in orbit.

The mission was originally scheduled to have completed by now, but low solar activity leading to lower than predicted atmospheric density and drag have extended the orbital lifetime. Based upon the state vector initially provided by Rocket Lab after deployment, our best assessment is that CubeSail is Space-Track Object #43853 (“Object E”) which began with an average orbital altitude of 505 km and has only decayed to an average altitude of 485 km as of 5 April 2021. As originally planned, CubeSail would begin sail deployment when it reached an altitude of 350 km. At its present rate of decay with a much lower than anticipated atmospheric density, this altitude is not likely to occur until December of 2023, or 5 years after launch. The bus electronics were only designed for a 2-3 year lifetime, so the 5-year decay is well beyond CubeSail’s original design.

The CubeSail team consisted of roughly 100 engineers, students, and NASA advisors over the course of its lifetime from concept to launch.  Our humble thanks go out to all those involved over the years starting from its proposal in 2005.  While the CubeSail mission did not ultimately go as planned, we take away a great many lessons learned and the education of countless engineers in this exhilarating, albeit at many times frustrating, field of spaceflight!


The CubeSail mission is a first in a series of increasingly complex demonstrations leading up to a fullscale UltraSail mission.