Exactly How We Would Send our First Laser-Powered Probe to Alpha Centauri

"Both [laser and magnetic sails] have the benefit that no propellant needs to be transported in the spacecraft... The mission is based on technologies that are currently available or under development, but would need extensive improvements to actually build the required space infrastructure... With a multi-spacecraft mission baseline, the laser system is used over a reasonable period of time. Lessons learned and data gathered from the first spacecraft could be used to enhance the following ones."

"Regarding the deceleration with a magnetic field, that is actually not possible within the parameters assumed. It would take a magnetic sail weighing several hundred tons to do the job when the craft cruises at 5% of the speed of light and when it has to come to a stop within 20 years, as assumed in the present paper. To accelerate such a heavy craft, much stronger launch systems would be required."