Space-Based Solar Sails Perform Under Pressure

Here’s a different side to solar energy. It’s space-based but not photovoltaic, and it doesn’t harness solar heat nor collect solar radiation. Instead, solar sailing utilizes the pressure of sunlight to move a ship or satellite through outer space.

The concept of a solar sail (a large kite made of reflective materials with satellite attached) has been studied in several countries for many years but to very limited success. Two launch attempts failed, preventing the sails from ever reaching orbit.

Solar sails work because photons of light have momentum. Should that momentum be interrupted by a giant, reflective sail floating in space, then it would transfer a portion of that energy onto the sail, propelling the satellite in a direction regulated by the positioning of the sail in relation to the sun or light source. Got all that? Granted, this transfer of energy is minute, but in the vacuum of space, little propulsion is needed and speeds from solar sailing increase over time.

Even more groundbreaking may be the solar sail’s uncanny ability to remain motionless in orbit for an extended period of time – longer than any fuel-propelled spacecraft could manage. Scientists hope to position a sail above the earth’s poles to give extended views of the effects of climate change on those poles and the planet. They plan to accomplish this hovering effect by positioning the solar sail at a point where the propulsion received from solar photons exactly matches the gravitational pull of the earth. Scientists can then study effects of global warming in a way that is yet impossible.

Photo Credit: PhysOrg

Posted on September 17th in Solar Information by Dan.