Laser Sails: Pushing Spacecraft with Light

Laser sails use powerful beams of light to push spacecraft, like wind pushing a sail.
Instead of fuel, they rely on radiation pressure from lasers or sunlight.
A spacecraft with a laser sail could reach a significant fraction of light speed.
The sails must be ultra-thin and lightweight, often just microns thick.
The concept could allow probes to reach nearby stars within decades.
Breakthrough Starshot plans to use laser sails to send gram-sized probes to Alpha Centauri.
Without onboard fuel, laser sail spacecraft could be much cheaper and lighter.
Steering is achieved by slightly tilting or reshaping the sail.
Challenges include building massive ground-based lasers and protecting the sails from damage.
Laser sails may be the first realistic step toward interstellar travel.