Solar Sails Hit Drag at 75%
Researchers discover relativistic speeds create unexpected drag, threatening to slow down interstellar travel by decades
Interstellar solar sails have hit a strange problem at 75% of light speed due to relativity, where scattered photons create drag, adding an obstacle to interstellar travel. Researchers from the Harbin Institute of Technology found that the same light used to propel the sail could eventually produce a drag effect.
The forces produced by photons striking a solar sail can be separated into three categories: incident light, specular reflection, and diffuse scattering. At relatively low speeds, these effects all contribute to pushing the sail forward. However, as the sail reaches relativistic velocities, the situation becomes more complicated.
The Doppler Effect weakens the push of the solar sail as it reaches high speeds. Additionally, relativistic light aberration becomes important at around 75% of the speed of light, causing diffusely scattered light to be directed forward, which creates drag.
Researchers Chao Shen and Jiaze Li of the Harbin Institute of Technology published a paper on arXiv about the problem, discussing the effects of relativity on solar sails and the creation of drag at high speeds. Their findings highlight a new challenge for interstellar travel, which requires reaching significant fractions of the speed of light to achieve in a practical amount of time.
## Why it matters Reaching another star within a practical amount of time will require a propulsion system far more capable than chemical rockets. Solar sails pushed by powerful lasers are a leading idea, but the newly discovered drag effect adds to the challenges of interstellar travel. As scientists continue to explore ways to overcome this obstacle, the development of interstellar travel remains a complex and ongoing challenge.
## What happens next The discovery of the drag effect at 75% of light speed will likely lead to further research into the effects of relativity on solar sails. Scientists will need to find ways to mitigate or overcome this obstacle in order to achieve the high speeds required for interstellar travel. As research continues, new technologies and strategies may emerge to address this challenge and bring humanity closer to reaching other stars.
