On September 25th, we announced that NASA would be launching the LLCD mission to conduct a communication test from the moon to Earth using lasers. On October 10th, we announced the fact that the LADEE spacecraft had just entered orbit around the Moon, and was beginning its series of experiments. Finally, on October 18th, NASA’s Lunar Laser Communication Demonstration (LLCD) successfully transmitted data from the Moon to the Earth at 622 Megabits-per-second (Mbps).
The ability to download data at rates that are 6 times faster than radio-frequency (RF) transmisions is a significant advancement in space communications, and could dramatically reduce data transmissions for other missions like those being conducted on Mars.
LADEE was a spacecraft created at NASA’s Ames Research Center and sent to the moon to investigate the unusual atmosphere there. Much is known about the surface of the moon, but there are still mysteries that remain about its atmosphere. However, as part of that mission, scientists also loaded up the LLCD to conduct the Moon-to-Earth laser communications tests that would forever transform the future of space communications. The successful tests on October 18th confirm the legitimacy of using lasers to communicate data over long-distances in space.
The Laser Communication Tests
After launching from Wallops Island, VA on September 6th, LADEE took 30 days to gradually reach lunar orbit. Once in orbit, the LLCD successfully demonstrated sending data to and from Earth over an astonishing distance of 239,000 miles. Communications took place between LADEE and NASA’s White Sands Complex in Las Cruces, NM.
Not only is the communication six times faster than RF communications, but the terminal used in space as part of the technology is only half the weight of modern radio-units, and the laser terminal uses 25 percent less power as well.
The communications tests involved sending high-definition video streams from the Moon to the Earth, and then in the other direction as well. The tests also included transmitting information between the LLCD and other locations as well, such as NASA’s Jet Propulsion Laboratory in California, and the European Space Agency (ESA) in Tenerife, Spain. The tests also included using the LLCD laser system to measure the position of the spacecraft from the Earth with a remarkable accuracy of under half an inch.
The Future of Laser-Based Communications
The idea of testing LLCD in a mission like that of the LADEE spacecraft is to demonstrate how the technology could be used for future space missions. This is the ultimate goal of the team – to create interest in the technology within other NASA teams. Dorn Cornwell, the LLCD manager told reporters:
“We hope this demonstration validates the capabilities and builds confidence in laser communication technology for consideration on future missions.”
Cornwell went on to describe his vision of how the technology could be used in the future:
“These first results have far exceeded our expectation. Just imagine the ability to transmit huge amounts of data that would take days in a matter of minutes. We believe laser-based communications is the next paradigm shift in future space communications.”
The technology is essentially similar to modern optical communications technologies like fiber-optics, however, the darkness of space provides for the ability to transmit data with a simple beam of light without the need to encapsulate it inside of a carrier device. With that said, the team plans to test the system in “optically stressed conditions” when the side of the Earth transmitting or receiving data does so during the daytime (as opposed to the nighttime, which is when all current tests were conducted).
The October demonstration of this technology also broke records – it was the longest-distance two-way laser communication ever conducted in history – only one of what is sure to become a series of record-breaking accomplishments through the use of this technology.
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