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Space exploration missions, completed using space probes take several years to complete. A space probe is a spacecraft with no astronauts that travels through space to collect information. It sends back data to Earth that scientists can study to better understand our universe.
The speed of these probes decreases in space due to a lack of gravity. For instance, a space probe named New Horizon, sent to Pluto took ten years to reach its destination, the dwarf planet in July 2015. Similarly, traveling to Proxima Centauri B, the star closest to our Sun will take thousands of years, even for big and advanced rockets.
To increase the speed of these probes and reduce their travel time, researchers at the University of California, Los Angeles suggested that low-power lasers on Earth can launch and move probes at a faster speed as compared to rocket engines. All they need to have is a boron or silicon nitride sail for propulsion.
Just as a sail catches the wind to move a boat, these space probe sails would catch laser beams to move the spacecraft at a high velocity. Researchers have been working on this concept for a while. On the other hand, a privately funded project known as the Breakthrough Starshot initiative is aiming to launch a sail probe on Proxima Centauri b soon. The probe weighs around one gram and is expected to take 20 years to reach the destination. It would be propelled by a 100GW power square laser to take up 20% of the speed of light, which is about 100 million miles per hour.
Ho-Ting Tung and Artur Davoyan wondered if low-power lasers can replace the chemical and electric power used in rocket thrusters. They expect that lasers might be able to adjust the satellites’ orbits after launch. These lasers might also propel tiny space probes on interplanetary or interstellar (missions beyond the solar system) missions thereby decreasing the probe’s dependence on fuel.
The researchers performed calculations to show that even low power lasers of 100KW with array or beam sizes of one meter can propel a probe weighing one gram to a high velocity exceeding their current record after providing illumination for minutes to hours. As per their calculations, the lasers were able to propel sailed probes between different orbits of the Earth in a single day. Currently, the motion of the probes in several Earth orbits is not possible with electric and chemical rockets due to a lack of fuel carrying capacity.
The researchers discovered that the best materials which allowed probes to move, increased their reflectivity and enabled rapid cooling were boron nitride and silicon nitride structured at the nanoscale level. Boron nitride maintained the thermal stability within the probes and silicon nitride provided thrust (energy) for motion.
Further, the researchers found that the probes could travel fast to escape the solar system. They acquired five times higher velocity than the New Horizon Probe. These prototype sailed probes driven by low-power lasers could speed up space exploration missions and future interstellar flight, the researchers concluded.
The detailed study has been published in the journal Nano Letters.
Contributed by: Simran Dolwani
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