Space Lasers | Imaging with Light

Our internet has gone from non-existent, to modems the size of VCRs playing horrible noises, to minuscule devices that can download and transmit huge amounts of information in a heartbeat (literally). The internet tools, as we know them, allow us to send school photos to Grandma, email entire PhD thesis, and store images from Hubble. 

On Earth, we have made huge leaps to improving the speed and reliability of data transmission. Space, however, is a different story. 

There are a lot of things that challenge our ability to transmit data in space. For example, you can’t transmit data through sound because sound waves can’t travel in space. That is because sound waves are called compression waves. When you yell it compresses the air right in front of your mouth in a specific way, and that then compresses air molecules further out, which then compress the molecules even further out, like ripples in a pond the sound ripples through the air. 

But space has nothing to ripple. No water, and no air. Space is a vacuum, so there is no medium (no, not even Ether) for the sound to transmit to. 

We got around this issue by transmitting our information with a different type of wave, an electromagnetic wave. Electromagnetic waves are the type of waves you see, not hear. 

We often know electromagnetic waves as light, different wavelengths of this wave create different colors of light. Some wavelengths, like radio waves, can’t be detected by our eyes because the wavelength is so long. 

But we have used radio waves to transmit data, I’ll let you guess how. Hint: they are named after something in your car! 

Radio waves can travel very long distances. Distances that span say, Pluto, to Earth. In fact, radio waves are how we have gotten every single one of our images from space, whether it is Pluto’s frozen heart, the footprints on the moon, or distant galaxies.

Downloading data with radio waves, however, has its limitations. For example, if you want to broadcast a message to Earth, you have to broadcast towards Earth. To the transmitter has to be directed properly. Since radio waves travel in a straight line, you also have to have your receiver in just the right spot to pick up the transmission.

There is also the problem that radio waves spread out as they move through space. The further you travel the more they spread out.

This means it takes longer to pick up data from more distant objects. Even within our solar system, it takes 1500 times longer to download the same image from Pluto than from Mars.

How could we transmit the data faster? Lasers. 

Lasers don’t spread out as quickly, and have a much shorter wavelength allowing you to transmit data much faster. 

In fact, we have already tried transmitting an image using lasers from the moon! The Mona Lisa in raw format, and after it has had some computer algorithms applied shows just how much better this form of talking in space could be!

Scientists are also working on a system of relays and satellites that can help capture the data. Right now there are basically three telephone lines from space to Earth, in the form of three massive radio dishes that receive our space data. Using lasers and satellite relays we can have a ton more phone lines, allowing more space agencies to learn, experiment, and discover interesting facts about our universe.

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