How fast does a solar sail go?
The speed of an interplanetary solar sail spacecraft will depend on how long it has been propelled by sunlight. The acceleration from sunlight is very small and depends on the size and weight of the sail and spacecraft. For our LightSail-1, the acceleration from the solar force will be approximately 0.06 mm per second per second. The real advantage of solar sailing is that, unlike a chemical rocket that applies a lot of thrust for a very short time, sunlight hitting the sail applies thrust continuously. In 100 days, a sail-propelled craft could reach 14,000 kilometers per hour. In just three years, a solar sail could reach over 150,000 miles per hour. At that speed, you could reach Pluto in less than five years.
