Laser sails for interplanetary voyages, by contrast, do not have to be as lightweight. For instance, Starshot aims to send probes to another star within a human lifetime, so its spacecraft are designed to be extraordinarily lightweight - each just 0.035 ounces (1 gram) or so - to fly as fast as possible given the amount of energy they receive. Going interstellar on a reasonable timescale imposes more constraints than voyaging within the solar system. "We do not need to wait till a 100-gigawatt laser becomes available." "Such lasers can be built already today with a relatively small investment," study senior author Artur Davoyan, a materials scientist at the University of California, Los Angeles, told.
In the new study, the researchers suggest that a more humble ground-based laser array - one that's 3.3 to 33 feet (1 to 10 meters) wide and 100 kilowatts to 10 megawatts in power - could still prove useful by sending tiny probes across the solar system, propelling them to much faster speeds than rocket engines could. It calls for a ground-based laser array on the order of 0.4 square miles (1 square kilometer) and as powerful as 100 gigawatts, which would be by far the most powerful laser ever made on Earth. The plan has them flying at up to 20% the speed of light, reaching Alpha Centauri in about 20 years.Ī major challenge Starshot faces is building the lasers needed for propulsion. Indeed, the $100 million Breakthrough Starshot initiative, announced in 2016, plans to launch swarms of microchip-size spacecraft to Alpha Centauri, each of them sporting extraordinarily thin, incredibly reflective sails propelled by the most powerful lasers ever built. Indeed, numerous experiments have shown that " solar sails" can rely on sunlight for propulsion if the spacecraft is light enough and has a large enough sail. Although light does not exert much pressure, scientists have long suggested that what little pressure it does apply could have a major effect. Previous research has suggested that " light sailing" might be one of the only technically feasible ways to get a spacecraft to another star within a human lifetime.