YEAR IN SCIENCE

摘要

In january 2013, the Lunar Reconnaissance Orbiter received a historic transmission: an image of the Mona Lisa. It was the first time scientists used a laser to send data to the moon, a feat that promises to exponentially increase the flow of information to and from space. For the past 50 years, spacecraft have relied on radio waves to communicate with Earth. But radio has limitations. Airwaves are crowded. Signals degrade with distance, so transmissions require power-hungry generators and large antennas. Focused laser light operates in wavelengths 10,000 times shorter than radio, pumping out more waves-and more information-each second. Lasers maintain signal strength across large distances, so transmitters require less power. And spacecraft carrying smaller receivers would be cheaper to launch.