Now, researchers determine in ACS Nano Letters that low-power lasers on Earth could introduce and steer small probes equipped with silicon or boron nitride sails, moving them to much faster speeds than rocket engines.
Instead of capturing wind, like the sails on boats, “laser sails” would catch laser beams and could, in concept, push spacecraft to almost the speed of light. The lasers might one day be able to adjust the orbit of satellites after launch or move tiny cruised probes on interplanetary or interstellar objectives, without needing big quantities of fuel.
The researchers performed calculations to reveal that even lasers with powers of about 100 kW and range sizes of about a meter could power a 1-gram probe at speeds far surpassing the existing record, with just minutes to hours of laser illumination.
Job Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be mankinds first interstellar voyage. Credit: breakthroughinitiatives.org
Space travel can be agonizingly slow: For example, the New Horizons probe took nearly 10 years to reach Pluto. Traveling to Proxima Centauri b, the closest habitable planet to Earth, would need countless years with even the greatest rockets. Now, scientists compute in ACS Nano Letters that low-power lasers on Earth could introduce and navigate small probes geared up with silicon or boron nitride sails, moving them to much faster speeds than rocket engines.
Instead of catching wind, like the sails on boats, “laser sails” would capture laser beams and could, in concept, push spacecraft to nearly the speed of light. Researchers have been dealing with this idea for a while. One privately moneyed project called the Breakthrough Starshot effort intends to send a small, cruised probe weighing about a gram to Proxima Centauri b with a flight taking only 20 years. It would be moved to 20% of light speed by a 100 GW, kilometer-square laser range. Ho-Ting Tung and Artur Davoyan wondered if much lower-power, smaller laser ranges might discover usage in applications where conventional electric and chemical rockets are now used. The lasers might someday have the ability to change the orbit of satellites after launch or propel small sailed probes on interplanetary or interstellar missions, without needing large amounts of fuel.
An artists conception of the Starshot Lightsail spacecraft throughout acceleration by a ground-based laser range. Previous conceptions of lightsails have actually envisioned them being passively pushed by light from the sun, but Starshots laser-based technique requires reassessing the sails shape and composition so it will not tear or melt throughout velocity. Credit: Masumi Shibata, courtesy of Breakthrough Initiatives
The scientists performed calculations to show that even lasers with powers of about 100 kW and array sizes of about a meter might power a 1-gram probe at velocities far surpassing the current record, with only minutes to hours of laser illumination. According to their estimations, the lasers could navigate little probes between different Earth orbits in only a day, which is not possible with existing electrical and chemical rockets. The team identified that the very best products for the laser sails, which permitted high reflectivity and quick cooling, were silicon nitride and boron nitride structured at the nanoscale.
The researchers calculated that these tiny laser-propelled probes might travel fast enough to leave the solar system, reaching 5 times higher velocities than the New Horizons probe. These prototype cruised spacecraft, driven by low-power lasers, might pave the wave for fast space expedition and future interstellar flight, the researchers state.
In this illustration, a low-power laser (red cone) in the world could be utilized to shift the orbit (red lines) of a little probe (grey circle), or move it at rapid speeds to Neptune and beyond. Credit: Adapted from Nano Letters 2022, DOI: 10.1021/ acs.nanolett.1 c04188.
Reference: “Low-Power Laser Sailing for Fast-Transit Space Flight” by Ho-Ting Tung and Artur R. Davoyan, 31 January 2022, Nano Letters.DOI: 10.1021/ acs.nanolett.1 c04188.
The authors acknowledge financing from NASA, the Air Force Office of Scientific Research, UCLA and the Hellman Society of Fellows.