Design and performance analysis of an inflatable film balloon for drag deorbiting

The quantity, total mass, and distribution region of space debris are constantly increasing, and simultaneously, over half of the low earth orbit satellite operators have no sustainable way to remove the failed satellites from space. Consequently, the growth rate of space debris after the end of a satellite's life considerably increases over time. Thus, the problem of removing space debris is very important.

Drag deorbiting is an efficient way to avoid space debris after micro-satellites fail. In this study, aiming at the deorbit problem using an inflatable film drag balloon, a design of omnidirectional drag after the inflated film balloon is presented. First, a hybrid folding method involving a closed 3D spherical shrinkage into a star-shaped compaction is proposed, which realizes a dense cube shape with zero-line width and variable thickness folding. Then, the air resistance effect in the low earth orbit is an important factor affecting the orbital height of satellite debris according to the atmospheric perturbation theory in drag balloon design, and NRLMSIE-00 model is used to predict the orbital atmospheric density. Based on the assumption of a small deformation spherical shell, the ultimate load regarding the spherical instability of the film drag balloon is analyzed, when the balloon is subjected the maximum air resistance at the height of 200 km. The ultimate loads of the film balloon at room (20℃) and high temperatures (80℃) are compared, and a test is validated in a vacuum chamber by a film balloon. Finally, the inflated balloon dragged by the space debris is considered as the perturbed deorbit motion caused by the air resistance effect. The relationship between the surface-to-mass ratio of various space debris and the balloon diameter with the deorbit time is analyzed, as well as the relationship of the deorbit time of the drag balloon with the orbit height.

Results showed that the polyimide film balloon can be used as a design for an omnidirectional drag deorbit for space debris. This hybrid folding method to a closed 3D inflatable sphere was used for the film balloon with a diameter of 1.8 m, which was reduced to 1/6 000 of its original volume after being folded into a dense cube shape. When the inflated film balloon with a deorbited micro-satellite, it was subjected to a small air resistance effect in the low-Earth orbit, the ultimate load of the polyimide film balloon with diameter of 1.8 m and thickness of 12.5 μm was within the safe range.

In brief, the ultimate load decreases exponentially with the increasement of balloon diameter; the larger the film thickness, the greater the ultimate load that the balloon can withstand. The ultimate load at room temperature is 0.400 0 Pa, while that at 80℃ is 0.330 0 Pa, thus, it is reduced by 17.5% with the increase in temperature. Under the same surface-to-mass ratio, the deorbit time increases with the increase of the deorbit height of the debris, however, under the same orbital height, the larger the surface-to-mass ratio of the space debris, the shorter the deorbit time.