Small-scale Experiments and Simulations of Centrifugal Membrane Deployment of Solar Sail Craft 'IKAROS'

ecently, a variety of solar sail spacecrafts using thin large membranes have been developed in US, Europe and Japan. In Japan, centrifugally deployed solar sails have been mainly investigated 1 . A solar power sail demonstration spacecraft “IKAROS” was developed by Japan Aerospace Exploration Agency and was launched on May 21th, 2010 by H-IIA launch vehicle. 2,3 Figure 1 shows an overview of “IKAROS” in space. The square solar sail with 20 meters in diagonal and 7.5 micrometers in thickness was successfully deployed by centrifugal force using no extendable booms. The sail consists of four trapezoidal petals which were folded up into strips and rolled up around the spacecraft in stowed configuration. The deployment of the membrane consists of two stages. In the first stage, the strips are quasistatically reeled out. In the second stage, the strips are dynamically unfurled. Since on-ground dynamic deployment experiments of the large membrane are impossible, small-scale experiments and numerical simulations are necessary to predict the deployment dynamics. In this paper, a deployment experiment of a smallscale square membrane similar to “IKAROS” is conducted in a vacuum chamber and corresponding numerical simulations are performed by employing a spring-mass system model. The deployment behavior is discussed and the results of the experiment and simulations are compared to examine the validity of the simulations.