Ground-based lasers could accelerate spacecraft to other stars

The future of space exploration includes some rather ambitious plans to send missions farther from Earth than ever before. Beyond the current proposals for building infrastructure in cis-lunar space and sending regular crewed missions to the moon and Mars, there are also plans to send robotic missions to the outer solar system, to the focal length of our sun's gravitational lens, and even to the nearest stars to explore exoplanets. Accomplishing these goals requires next-generation propulsion th...