Three axis stabilized solar sails use a structure that supports loads applied to the sail in 3 dimensions to prevent collapse of 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 2 dimensions that the sail surface approximates. Two common ideas for preventing collapse of the sail in the 3rd dimension, which is at right angles to the sail, are:

• Fix the booms firmly at the center so they cannot rotate.
• Place masts at the center of the sail oriented at right angles to the sail and interconnect the booms and masts with lightweight tension lines, or stays as sailors call them.

This first set of pictures depict square solar sails that use a combination of booms and tension lines to support the sail.

The first picture is a square solar sail in Earth orbit similar to a sail the Jet Propulsion Laboratory designed in the late 1970's to rendezvous with Halley's Comet during its last approach, but unfortunately was canceled. Low-thrust propulsion, like solar sails and ion engines, was the only feasible way to try to rendezvous with Halley's Comet in the short time available. The sail uses vanes at each corner of the sail which can be rotated to steer the spacecraft.

The second picture depicts another square sail making a rendezvous with a comet. This design has only two vanes at opposite corners, but can still provide full control of the sail.

The third picture shows a robotic Mars sample return mission carried by a square solar sail, while the fourth shows a human mission supported by solar sail. Using a sail similar to that designed for the Halley's Comet mission, a single solar sail could carry a large payload from Earth to Mars in 4 to 6 months every two years. Coming back from Mars, the sail passes through the inner asteroid belt before returning to Earth, where it can flyby a couple asteroids without losing any time returning to Earth. After a layover of about 3 months, the sail could leave for Mars and the asteroid belt again. This short short trip time makes solar sails a good option for carrying humans to Mars. This trajectory was developed by Jerome Wright.

These pictures were contributed by Jerome Wright, author of Space Sailing, and are courtesy of the Jet Propulsion Laboratory.

This was the original design by the Canadian Solar Sail Project for an effort to race to the moon in 1992 in honor of the 500 year anniversary of Columbus reaching the Americas. This sail has six sides and steers by tilting the segments of the sail like a venetian blind to change the direction sunlight pushes on the sail.

This picture is by Paul Fjeld, an artist/engineer who does a lot of PR illustration for the Canadian Space Agency, and was contributed by Christopher Neufeld.

These three pictures are of square solar sails modeled using Mops and rendered with the Blue Moon Rendering Tools. The first is a square solar sail that is supported by fixing the booms at the center to support bending and compression as sunlight pushes on the sail. It is very similar to the sail designed by the World Space Foundation for the Earth-Moon race. The second and third pictures are front and back views of the clipper sail designed by Jerome Wright as a refinement of the Halley Rendezvous sail designs shown above.

Here are the Mops and Rib files for these pictures:

• square.mop, square.rib
• clipper.mop, clipper.rib