Experimental cosmologist Philip Lubin recently presented interstellar space travel scenarios at the Optical Society’s Laser Congress in Boston, informed by his direction of the NASA Starlight and Breakthrough Starshot programs. Lubin, a professor of physics at the University of California, Santa Barbara, believes that by tapping into photonics-driven propulsion, researchers are well on their way to making laser-light-powered spacecraft that can deliver humans to Mars within one month. A major challenge in validating this photonics concept in relation to propulsion is the demonstration of the laser power required to accelerate the proposed/hypothetical spacecraft. Large directed energy systems are not built using a single gigantic laser, but instead rely on beam combining, which involves the use of many very modest power laser amplifiers. “Our system leverages an established typology called Master Oscillator Power Amplifier design,” Lubin said. “It’s a distributed system so each laser amplifier building block is between 10 and 1000 W. You can hold it in your hand. Instead of building a gigantic laser, you combine a lot of small little laser amplifiers that, when combined, form an extremely powerful and revolutionary system.” Lubin suggests an analogy with supercomputers, which are built using a large number of central processing units. “By coherently combining billions of low-power laser power amplifiers — similar to the same power of a typical modern household LED — you suddenly have this amazingly capable directed energy system,” he said. Directed energy systems may enable interstellar probes as part of human exploration, and they are at the heart of the Starlight and Breakthrough Starshot Initiative to enable humanity’s first interstellar missions. The same core technology has many other applications such as rapid interplanetary travel for high-mass missions, which include those carrying people; planetary defense; and the search for extraterrestrial intelligence.