To Alpha Centauri in 20 years: research into material for light sails begins
Tiny spaceships could be accelerated by lasers so that they reach the nearest star in 20 years. That's the theory. Now it's time to put it into practice.
(Image: Breakthrough Starshot)
Researchers at the California Institute of Technology have begun practical testing of a hypothetical propulsion concept for interstellar travel. The university has now made this public and explained that the experiments involve the concept of small nano-spaceships that are to be accelerated to relativistic speeds by lasers. According to the theory, this would enable them to reach other stars within a few decades. Research is now being carried out at Caltech into what material the wafer-thin membranes that make up the light sails could be made of.
From theory to practice
The research work is supported by the "Breakthrough Starshot" initiative, among others. It was launched nine years ago and, with the money of an Israeli billionaire, aims to show that we are able to build spaceships with existing technology that can reach up to 20 percent of the speed of light. To do this, the tiny devices, suspended from sails just a few meters in diameter, are to be accelerated by laser beams that target them from the Earth's surface. It would then take them just 20 years to travel to the Alpha Centauri star system four light years away, but they would have extremely little time to explore the system –. It is not possible for the spaceships to slow down.
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There are numerous challenges in developing a membrane that could be used to build such a light sail, explains Harry Atwater from Caltech: "It has to be heat-resistant, retain its shape even under pressure and move stably along the axis of the laser beam." Before you can start building such sails, you first have to understand how the material behaves under laser pressure. The aim is to investigate the behavior of a freely movable membrane in the future. However, they have now started with a miniature version that is attached to a larger membrane.
Using special equipment, the team has produced a membrane made of silicon nitride that is just 50 nanometers thick. Measuring just 40 micrometers by 40 micrometers, it looks like a microscopic trampoline. The structure is attached at the corners and illuminated by light from an argon laser. The pressure exerted by the light was then determined. The analysis was made more difficult by vibrations, which are mainly caused by the heat of the laser. However, they were able to measure the movement of the membrane with picometer precision. This provides the team with a platform for investigating other materials. The experiments are presented in detail in a research paper in the journal Nature Photonics.
(mho)
