NASA Space Laser to Make Radio Obsolete

R. Colin Johnson

Radio-based space communications could be made obsolete by a laser-based long-haul optical connection that runs 10 to 100 times faster.NASA will demonstrate a long-haul optical network by connecting California and Hawaii with a laser communication link that works similarly to fiber optics, sans the fiber. Called a free-space optical connection--as opposed to within a fiber--the first demonstration will show that long-haul lasers can communicate with pulses of light at 100M bps.
Today, space probes must transmit data back at 6M bps using radio waves, taking almost 90 minutes to receive a single 4GB high-resolution image. However, by encoding the bits on laser beams--like terrestrial long-haul fiber-optic networks--that same image would take only approximately five minutes to transmit. Similar to fiber-optic telecommunications--sans the fiber--NASA hopes to demonstrate its free-space optical transceivers between ground bases in California and Hawaii by bouncing their communications laser off a satellite. If the test is successful, NASA's Laser Communications Relay Demonstration Mission (LCRD) could also allow remote telepresence capabilities where astronauts would use remote-control robots to visit heavenly bodies virtually.

Laser Communications Relay Demonstration (LCRD) will act as a long-haul fiber-optic network--sans the fiber. (Source: NASA)

"Optical communication will enable a rapid return of the voluminous data associated with sending spacecraft and humans to new frontiers," said NASA Chief Technologist Bobby Braun at NASA headquarters in Washington during the announcement of the technology demonstration program for its laser-based communications. The $175 million NASA Technology Demonstration Mission program will support two other missions--one testing a new atomic clock for precise space navigation, and the other a solar-sail for propellant-free propulsion.
According to NASA, free-space laser communications not only provide significantly higher data rates, compared with radio-frequency communications, but lasers also decreased the mass, size and power consumption of the spacecraft using them. The project could also allow real-time data streaming from instruments that today must store-and-forward files, like hyper-spectral imagers and synthetic aperture radar (SAR). And for astronauts, laser-speeded communications will allow them to use telepresence to safely investigate nearby planets, moons and asteroids.
NASA Goddard Space Flight Center (Greenbelt, Maryland) will build the Laser Communications Relay Demonstration (LCRD) system with the Space Communications and Navigation (SCaN) office in the Human Exploration and Operations Mission Directorate and the NASA Office of the Chief Technologist. The mission, which is just one of three technology demonstration missions, will take four years to achieve and is slated to be finished in 2016. The other two technology demonstration missions--a deep-space atomic clock for precise space navigation and a propellant-free solar-sail propulsion system--will run in parallel, but will only take three years to achieve, and will be demonstrated in 2015