Can a Laser Light Travel Through Earth's Atmosphere and into Outer Space?

The concept of space is often misunderstood, with it being commonly referred to as "outer space" in fiction. However, space is simply the vast expanse beyond Earth's atmosphere, where no such barrier exists. Lasers, particularly those used in astronomy, can indeed travel through the Earth's atmosphere and even reach the moon.

Lasers Shining Across Space

Astronomical sites often use powerful lasers to communicate with reflectors placed on the moon. For instance, lasers from Lick Observatory can measure the distance to the moon with centimeter-level accuracy. These lasers are much more powerful than the typical laser pointers used in presentations, with the ability to travel vast distances through space.

Energy Transmission via Laser Beams

The idea of using photovoltaic cells to convert sunlight into laser beams for power transmission is not only feasible but also highly promising. Blue laser-based remote power beaming systems can enable practical energy distribution for future explorers on the moon, which is just a shade over one second away in time, and to Mars, which is approximately 290 million miles away.

Theoretically, a giant laser array could be used to propel spacecraft to Mars in 45 days, a task that traditionally would take much longer due to conventional propulsion methods. This technology also holds potential for generating clean energy on Earth. Solar lasers could be used to generate power locally on space stations and to send power to satellites or even back to Earth.

The Role of Atmosphere in Laser Propagation

While the atmosphere does play a role in how laser light propagates, it is not an insurmountable barrier. At its core, the atmosphere is simply a thick layer of gases surrounding the Earth, and light of various frequencies can pass through it to varying degrees.

Atmospheric scattering is what allows us to see light sources even when they are not directly pointing at our eyes. However, the level of absorption and scattering varies with the strength of the laser. Laser pointers, for example, generate such a small amount of energy that only a tiny fraction of their light would reach the edges of the Earth's atmosphere, after which it would continue to propagate into space.

Stronger lasers, on the other hand, such as those used in experimental setups like the one at Lick Observatory, would have a much higher probability of making it past the atmosphere, especially if they operate at frequencies that are not easily absorbed by atmospheric gases.

In conclusion, while the atmosphere can absorb some of the laser light, it is not an insurmountable barrier to laser propagation into space. Technologies leveraging laser-based power beaming hold great promise for space exploration, clean energy generation, and more.