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When you hear the term ‘space laser,’ your mind likely leaps to weapons technology. Indeed, lasers can be used as lasers, and a giant laser gun in space would be a huge threat. Fortunately, China’s new space laser isn’t made to attack, but rather to locate other satellites and prove out the possibility of using lasers for communication during the day.
The researchers set out to find the Tiandu-1 satellite, which was about 130,000 kilometers (81,000 miles) away from Earth, orbiting the moon. To do this, they sent a laser from their Earth station, bounced it off a retroreflector device that was placed on the Tiandu-1 satellite, and had it return to Earth, all in less than a second. The returning laser was seen by a 1.2-meter telescope located at the Chinese Academy of Sciences Yunnan Observatories.
This is a pretty remarkable achievement given the distances and the fact that it happened during a time when the objects were exposed to the sun’s light. Lasers are great for many things, but can be disrupted by the bright sun.
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Lasers are often used in space for things like measuring distance, communicating, determining location, and more. NASA, for example, has used lasers to locate two separate craft on the moon’s surface. The laser was shot by the Lunar Reconnaissance Orbiter (LRO) and detected both India’s Vikram lander and the Smart Lander for Investigating Moon (SLIM) from Japan.
What makes this particularly remarkable is that the LRO wasn’t designed for this type of use. Xiaoli Sun led the team that built the SLIM’s retroreflector at NASA’s Goddard Space Flight Center. He put out a statement, saying:
“LRO’s altimeter wasn’t built for this type of application, so the chances of pinpointing a tiny retroreflector on the Moon’s surface are already low.”
This type of test shows that lasers can indeed be used even in the bright sun. This may be important if bases are ever set up on Mars, where it takes around 8 minutes for light to travel between there and Earth.
Using lasers for communication would be much more efficient than radio waves, since it would be possible to encode much greater amounts of data.
If you thought that was interesting, you might like to read about a quantum computer simulation that has “reversed time” and physics may never be the same.