Nasa is about to radically change the way it communicates between space and Earth. Historically the space agency has beamed data to Earth using radio-frequency communication but now it is working on a laser-based space communications system.
Officials at NASA say this new form of communication system is key to securing rapid and accurate transmission of information from spacecraft that is positioned around the solar system.
“With missions developing more highly detailed science and larger volumes of data, radio-based communication links can be overwhelmed by the sheer amount of data being pushed to the ground, providing a need for higher data rates that can only be achieved with optical communication,” NASA officials wrote in a description of the agency’s Laser Communications Relay Demonstration mission (LCRD), which is due to begin in December 2017.
NASA’s plan is for LCRD to launch into geosynchronus orbit as a hosted payload on a commercial communications satellite, which has been developed by Space Systems. Two optical modules will use lasers to beam information to two stations situated in California and New Mexico at rates of up to 1.25GB per second.
LCRD will run for at least two years, allowing enough time to show the long-term viability of space-based laser communication systems. It will be heavily based on the Lunar Laser Communications Demonstration (LLCD), which launched to the moon last month.
Bernard Edwards, chief communications systems engineer at NASA’s Goddard Space Flight Centre, says that the LLCD system is more efficient than using radio-frequency as it needs significantly less mass and power. “So we’re really excited about what this means for the future,” he said Oct. 23 during a presentation with NASA’s Future In-Space Operations working group.
Although there are many advantages with optical communication, the technology throws up some challenges too. For one, the costs are quite high.
“What we’re trying to do is to commercialize this to figure out how to drive the cost down,” he said. “We have a strategy that we’re currently executing that we think will make this affordable in the future.”
Another problem facing NASA is pointing accuracy because laser beams are very tightly focused. “As you go farther out into deep space, it becomes more problematic,” Edwards said.
To overcome this, laser systems that work beyond the Earth-moon system will need to be a lot larger and more powerful, with bigger receivers based on Earth. This is something NASA hopes to launch in the near future.
“That work is being undertaken by the Jet Propulsion Laboratory, on something called the Deep Space Optical Terminal,” Edwards said. “That’s currently in technology development, in concept development. We don’t have an actual flight project yet, with a committed funding source and a committed satellite. But we hope to fly something later on in the decade.”
[Image via NASA Goddard Space Flight Centre]