LLCD: Laser demo reveals bright future for space communication

Compared to the days of dial-up, today's web-sites load at lightning speed. 

Just like you need your web-pages load quickly and securely, NASA scientists and engineers want the same quick connectivity with their data-gathering spacecraft. 

To meet these demands NASA is moving away from their form of dial-up (radio frequency-based communication), to their own version of high-speed Internet; using laser communications. 

Credit: NASA

The completion of the 30-day Lunar Laser Communication Demonstration (LLCD) mission has revealed that the possibility of expanding broadband capabilities in space using laser communications is as bright as expected.

Hosted aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE), for its ride to lunar orbit, the LLCD was designed to confirm laser communication capabilities from a distance of almost a quarter-of-a-million miles.

In addition to demonstrating record-breaking data download and upload speeds to the moon at 622 megabits per second (Mbps) and 20 Mbps, respectively, LLCD also showed that it could operate as well as any NASA radio system.

"Throughout our testing we did not see anything that would prevent the operational use of this technology in the immediate future," said Don Cornwell, LLCD mission manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

For example, LLCD demonstrated error-free communications during broad daylight, including operating when the moon was to within three degrees of the sun as seen from Earth.

LLCD also demonstrated error-free communications when the moon was low on the horizon, less than 4 degrees, as seen from the ground station, which also demonstrated that wind and atmospheric turbulence did not significantly impact the system. LLCD was even able to communicate through thin clouds, an unexpected bonus.

Operationally, LLCD demonstrated the ability to download data from the LADEE spacecraft itself. "We were able to download LADEE's entire stored science and spacecraft data [1 gigabyte] in less than five minutes, which was only limited to our 40 Mbps connection to that data within LADEE" said Cornwell.

Using LADEE's onboard radio system would take several days to complete a download of the same stored data.

Additionally, LLCD was to prove the integrity of laser technology to send not only error-free data but also uncorrupted commands and telemetry or monitoring messages to and from the spacecraft over the laser link.

NASA Administrator Charles Bolden congratulates the LLCD team on their successful demonstration of laser communications in a video that was relayed via laser to and from the moon. 

Credit: NASA's Goddard Space Flight Center

LLCD also demonstrated the ability to "hand-off" the laser connection from one ground station to another, just as a cellphone does a hand-off from one cell tower to another.

An additional achievement was the ability to operate LLCD without using LADEE's radio at all.

"We were able to program LADEE to awaken the LLCD space terminal and have it automatically point and communicate to the ground station at a specific time without radio commands. This demonstrates that this technology could serve as the primary communications system for future NASA missions," said Cornwell.

NASA laser communication system sets record - Data transmissions to and from Moon

NASA's Lunar Laser Communication Demonstration (LLCD) has made history using a pulsed laser beam to transmit data over the 239,000 miles between the moon and Earth at a record-breaking download rate of 622 megabits per second (Mbps).

LLCD is NASA's first system for two-way communication using a laser instead of radio waves.

It also has demonstrated an error-free data upload rate of 20 Mbps transmitted from the primary ground station in New Mexico to the spacecraft currently orbiting the moon.

"LLCD is the first step on our roadmap toward building the next generation of space communication capability," said Badri Younes, NASA's deputy associate administrator for space communications and navigation (SCaN) in Washington.

"We are encouraged by the results of the demonstration to this point, and we are confident we are on the right path to introduce this new capability into operational service soon."

Since NASA first ventured into space, it has relied on radio frequency (RF) communication.

However, RF is reaching its limit as demand for more data capacity continues to increase.

The development and deployment of laser communications will enable NASA to extend communication capabilities such as increased image resolution and 3-D video transmission from deep space.

"The goal of LLCD is to validate and build confidence in this technology so that future missions will consider using it," said Don Cornwell, LLCD manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

"This unique ability developed by the Massachusetts Institute of Technology's Lincoln Laboratory has incredible application possibilities."

LLCD is a short-duration experiment and the precursor to NASA's long-duration demonstration, the Laser Communications Relay Demonstration (LCRD).

LCRD is a part of the agency's Technology Demonstration Missions Program, which is working to develop crosscutting technology capable of operating in the rigors of space. It is scheduled to launch in 2017.

LLCD is hosted aboard NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), launched in September from NASA's Wallops Flight Facility on Wallops Island, Va. LADEE is a 100-day robotic mission operated by the agency's Ames Research Center at Moffett Field, Calif. LADEE's mission is to provide data that will help NASA determine whether dust caused the mysterious glow astronauts observed on the lunar horizon during several Apollo missions.

It also will explore the moon's atmosphere. Ames designed, developed, built, integrated and tested LADEE, and manages overall operations of the spacecraft.

The LLCD system, flight terminal and primary ground terminal at NASA's White Sands Test Facility in Las Cruces, N.M., were developed by the Lincoln Laboratory at MIT.

The Table Mountain Optical Communications Technology Laboratory operated by NASA's Jet Propulsion Laboratory in Pasadena, Calif., is participating in the demonstration.

A third ground station operated by the European Space Agency on Tenerife in the Canary Islands also will be participating in the demonstration.

More information: esc.gsfc.nasa.gov/267/271.html