Infrared Laser Network Could Revolutionize Satellite Communications Amid Increasing Orbital Crowding

Infrared Laser Network Could Revolutionize Satellite Communications Amid Increasing Orbital Crowding
Image credit: IEEE Spectrum 

The Challenge of Growing Satellite Numbers

With approximately 5,000 satellites currently orbiting Earth and projections suggesting up to 100,000 could be in space by the end of the decade, low-Earth orbit is becoming increasingly congested. The limited radio and microwave frequency spectrum, ranging from 1 to 40 gigahertz, is facing a severe data bottleneck for satellite-to-Earth connections.

Introducing TeraNet: The Infrared Solution

Astronomers have proposed an innovative alternative. Researchers at the University of Western Australia’s (UWA) International Centre for Radio Astronomy Research in Perth are developing a network of infrared laser base stations—two ground stations and a mobile station—dubbed the TeraNet project. These stations use 200 THz waves, which offer significantly more data capacity than traditional radio waves. Last month, the team successfully captured signals from a German low-Earth orbit satellite, marking a critical step towards next-generation space communications.

Building TeraNet on a Budget

Sascha Schediwy, research group leader in astrophotonics at UWA’s International Centre, highlighted that TeraNet was built using off-the-shelf technology. "We’re validating that you can build these complex ground stations on a modest budget. You don’t need to be a national space agency like NASA to get into free-space optical communications," he said. Each ground station’s core component is a commercially sourced, larger version of an optical telescope typically used for stargazing.

A telescope mounted on the back of a jeep provides a mobile data station for a laser-based satellite communications system, called TeraNet
Image credit: IEEE Spectrum 

How TeraNet Works

When encoded with data, the infrared laser beam is transmitted through the telescope to a specific satellite as it passes over the ground station. Similarly, data sent from a satellite to the ground station is directed down to the ground station’s telescope, filtered, processed, and converted from an optical signal into digital data by the optical modem.

Overcoming Atmospheric Challenges

Laser data links between ground stations and satellites can be disrupted by overcast skies, rain, or adverse weather conditions. To mitigate this, researchers have geographically dispersed the ground stations so that a satellite can transmit data to another station under clear skies if one is clouded out.

Demonstrating the Infrared Downlink

The team demonstrated the technology using a ground station with a 70-centimeter telescope and a mobile station with a 43-centimeter scope, in data-receiving mode only. Schediwy explained, "The tricky part in moving outside of fiber into free space is that the turbulence in the atmosphere perturbs the signal and changes the waveform hundreds of times a second."

A prototype network of two telescopes—one mobile and one based at an observatory at the University of Western Australia in Perth—tests technologies being developed for laser-based satellite communications.
Image credit: IEEE Spectrum 

Mobile Station Innovation

The mobile station, built on a custom Jeep, uses compasses, GPS, and an inertial navigation unit to determine its position and orientation. The algorithm points the telescope at the expected direction of the satellite as it arrives over the horizon. Unlike other mobile ground stations, which can take hours or days to set up, TeraNet’s mobile station can be operational in about 15 minutes, day or night.

Future Upgrades and Network Expansion

The satellite data, transmitted on a 1,550-nanometer infrared laser, has so far delivered data throughput in megabits per second. "But with the technology proven," Schediwy said, "we will now upgrade the equipment and work towards our roadmap target of 1 terabit-[per]-second bandwidth by the end of 2026." Collaborations with the Australian National University in Canberra and other organizations aim to establish larger networks of ground stations in Australia and New Zealand.

Global Impact and Compatibility

Schediwy emphasized the importance of compatibility among ground stations worldwide. "If we can all make our ground stations compatible, then satellite operators can be assured that they will have secure download capabilities in Europe, in Australia, and elsewhere, as their satellites orbit the world."