Goddard Wins Paradigm-Shifting LaserComm Mission
January 20, 2017
Scientists Call Mission Long Time Coming
Goddard technologists have won millions of dollars in NASA funding to demonstrate a space-based optical communications system that could make today’s radio-frequency systems look as passé as dial-up Internet and give scientists what they’ve long wanted: High-speed data rates and the potential streaming of high-definition video from distances beyond the Moon
“We always dreamed of having laser communications, which could increase data rates by anywhere from 10 to 100 times,” said Goddard Chief Scientist Jim Garvin, a long-time proponent of the technology, reacting to news of the Goddard win. “We’ve been waiting for more than a decade.”
This artist's rendition shows the mission concept of the Laser Communications Relay Demonstration project that NASA recently selected.
The Laser Communications Relay Demonstration (LCRD) will demonstrate this long-awaited capability. One of three projects selected by NASA’s Office of the Chief Technologist (OCT) for a trial run, the demonstration involves a hosted payload on a commercial communications satellite developed by Space Systems/Loral, of Palo Alto, Calif., and two specially equipped ground stations in California and Hawaii. The demonstration is expected to launch in 2016 and operate two to three years.
“We want to take NASA’s communications capabilities to the next level,” said LCRD Principal Investigator Dave Israel, who is leading the multi-organizational team that includes the Jet Propulsion Laboratory and Lincoln Laboratory at the Massachusetts Institute of Technology (MIT). Although NASA has developed data-compression technologies and other techniques to boost the amount of data that its current systems can handle, the Agency’s capabilities will not keep pace with the projected data needs of advanced instruments and future human exploration, Israel added.
“Just as the home Internet user hit the wall with dial-up, NASA is approaching the limit of what its existing communications network can handle,” he said, likening the emerging capability to land-based fiber-optic systems, such as Verizon’s FiOS network, which have allowed the high-speed delivery of telecommunications, data, and voice. “In a sense, we’re moving FiOS to space.”
No one expects laser communications to completely replace NASA’s radio-frequency network, which includes a fleet of tracking and data relay satellites and a network of ground stations. Furthermore, the transition to optical systems will take years to complete, but the eventual payback will be very large increases in the amount of data NASA can transmit.
“Right now, exploration beyond Earth is data-starved,” Garvin said. “We have to be so careful about every bit of data we collect because our current systems cannot accommodate increased data collection. This is a long-awaited step in the right direction.”
To demonstrate the new capability, the Goddard team will encode digital data and transmit the information via laser light from ground stations to an experimental payload hosted on the commercial communications satellite.
The payload will include telescopes, lasers, mirrors, detectors, a pointing-and-tracking system, control electronics, and two different types of modems. One modem is ideal for communicating with deep-space missions or tiny, low-power smallsats operating in low-Earth orbit. The other can handle much higher data rates, particularly from Earth-orbiting spacecraft, including the International Space Station. “With the higher-speed modem type, future systems could support data rates of tens of gigabits per second,” Israel said. Once the payload receives the data, it would then relay it back to the ground stations.
The multiple ground stations are important for demonstrating a fully operational system, Israel said. Cloud cover and turbulent atmospheric conditions impede laser communications, requiring a clear line of sight between the transmitter and receiver. If bad weather prevents a signal from being sent or received at one location, the network could transfer the responsibility to one of the other ground stations or store it for later retransmission.
Follow-On to LADEE Experiment
The project isn’t NASA’s first foray into laser communications. NASA hired the MIT-Lincoln Laboratory to develop a laser communications payload for NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE), which the Agency plans to launch in 2013. The main goal is proving fundamental concepts of laser-based communications and transferring data at a rate of 622 megabits per second, which is about five times the current state-of-the-art from lunar distances.
However, the LADEE payload is equipped with only one modem, the lower-speed model best suited for deep-space communications. In addition, LADEE is a short-duration mission. The experiment is expected to operate for only 16 days of the LADEE mission, not enough time to demonstrate a fully operational network, Israel said.
LCRD isn’t NASA’s first attempt at demonstrating an operational system, either. Before LADEE, NASA had begun developing the Mars Telecommunications Orbiter, but canceled the project in 2005 because of budget constraints. Had it launched in 2009, it would have exhibited high-speed data rates between Earth and several Mars landers and orbiters for as long as 10 years.
With the new NASA commitment to finally field a demonstration, scientists say they could not be more pleased. “This is really a potential paradigm shifter,” Garvin said. “It will lower risks, enable smarter spacecraft, and in short provide better value for the taxpayer. It means we have our foot in the door to provide a capability NASA has long needed.”