A laser array on Earth could propel tiny space probes at very high speeds to their destination. (Image Credit: Nano Letters 2022, DOI: 10.1021/acs.nanolett.1c04188)
Traveling to faraway planets in the solar system takes many years, achieved through today’s spacecraft. For instance, NASA’s New Horizon probe embarked on a ten-year journey to reach Pluto. According to a new study, cell phone-sized spaceships featuring laser-driven sails could trek across the solar system, reaching faraway destinations at much faster speeds than spaceship-powered rockets.
Research conducted in the past revealed that “light sailing” might be a feasible solution for flying spacecraft to a distant star. While light applies minimal pressure, scientists believe that it could still play a significant role in propulsion. If a spacecraft is lightweight with a large sail, it could use sunlight to push forward.
The Breakthrough Starshot initiative plans on launching packs of microchip-sized spacecraft for a 20-year journey to Alpha Centauri, traveling at 20% the speed of light. The spacecraft, weighing 0.035 ounces, would feature ultra-thin, extremely reflective sails propelled by the world’s most powerful lasers. However, developing the lasers for this purpose presents a significant challenge. It requires a ground-based laser array, which would need to be as powerful as 100 gigawatts and cover 0.4 square miles.
The latest study reveals that a 3.3 to 33 feet wide and 100 kilowatts to 10 megawatts ground-based laser array could propel tiny space probes across the solar system. Even then, solar sails won’t need to be very lightweight. The scientists behind the study suggest the probes can weigh 3.5 ounces, similar to a cell phone. As a whole, all the required components, including particle detectors, cameras, accelerometers, spectrometers, and more, can easily fit inside a 3.5-ounce probe. These are essential for spacecraft to perform scientific missions.
A laser array could also transport a swarm of tiny probes carrying equipment to a specified region. In such cases, one may be a magnetometer probe. Meanwhile, the other would have a camera, while the third operates as a particle detector. The scientists envision using many small probes to perform scientific missions in different destinations.
So far, the U.S. military is developing 100-kilowatt laser arrays. In 2020, the U.S. Navy’s littoral combat ship USS Little Rock was equipped with a 150-kilowatt laser. Additionally, high-powered lasers are starting to become more affordable every year, with a 1-kilowatt laser costing under $10,000. That’s because optical telecommunications systems are in high demand.
Interplanetary travel wouldn’t need to rely on large sails that can withstand the light and the same powerful lasers used for Starshot. The researchers propose using 4-inch wide silicon nitride or boron nitride sails for flights within the solar system. They also calculated that a 0.0035-ounce spacecraft with a 4-inch sail traveling approximately 112,000 mph could reach Mars in just 20 days, Jupiter in 120 days, and Pluto in under three years. It could also reach 100 times the distance of Earth in just ten years.
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