Rocket fuel and chemical energy has always been a big hurdle in deep space exploration probes sent to the corners of the solar system. Scientists and researchers have been trying for long to overcome this obstacle in space exploration and have come up with the solar sails. Solar sails will harness the energy of sunlight to propel space crafts, just like early ships used to harness the energy of wind.
Sun is continuously emitting light or photons. Since photons have mass and are in motion, hence they have momentum and exert a force when reflected from a surface. The solar sails reflected surface transforms the continuous force of photons to propel the space craft through space. Hence solar-sail powered spacecrafts are, fuel and engine free, with the sunlight as its continuous source of power, acting as an engine.
On Earth, sunlight can produce 1.4Kw of power, which exert a pressure of about 9 newtons/ square mile, whereas a space shuttle engine can generate thrust of 1.67 million newtons of force on earth during lift off and 2.1 million newtons in space. The force by the solar sail is much smaller, but, since sun is continuously powering and accelerating the solar sails, it can reach speeds up to 1,55,000 miles/hr.
A single-quadrant, 10-meter solar sail system sits fully deployed in a 50-foot-diameter vacuum chamber at NASA's Langley Research Center in Hampton, Va.(Photo courtesy NASA)
Solar sails are made of materials as light as 10 gm/square meter. NASA has been working to manufacture materials with thickness of few microns and can still withstand the harsh environment of space.
Scientists believe that the development of solar sails will open new prospects of deep space explorations and interstellar space missions.
