Three-Axis Stabilized

Many solar sail designs use a rigid structure, much like a kite, to hold the sail out to catch sunlight. This is called three axis stabilization, because the structure supports the sail in all three dimensions, or axes, without spinning. The three dimensions come from the two dimensions that lie within the surface of the sail, and the third dimension that is perpendicular to the sail.

Attaching the outer edges of the sail to stiff booms that meet at the center of the sail is a good way to prevent collapse in the plane of the sail. The next problem is to prevent these booms from collapsing in the third dimension, like an umbrella being folded. Two common ideas for achieving this are:


 * Booms
 * Booms, Masts, and Stays

Any other structure that prevents the sail from collapsing, like a stiff outer torus, could work as well.

Booms
If booms alone are to support a solar sail, they must act as columns and as beams. As columns, the booms prevent the sail from collapsing inward towards the center. As beams, the booms are stiff and fixed at the center, like a diving board, to prevent the sail from folding up like an umbrella. Here are some examples of solar sails that stabilized in this manner.

Booms, Masts, and Stays
Using a combination of booms, masts, and stays, a 3-axis stabilized solar sail can be made lighter, at the cost of the complexity. By supporting the booms with masts and stays, they only need to act as columns, and not as beams. The masts are set perpendicular to the booms and stays connect between the booms to each other and to the masts. The booms can be made much lighter because the stays and masts prevent the sail from folding up. This kind of structure is similar to a very tall radio antenna that is supported by cables. The following pictures give some example of solar sails with this kind of structure.