Satellite firm Spire has successfully demonstrated optical laser communications between two of its satellites.

The space-to-cloud data and analytics developer Spire Global this week announced it has achieved its first two-way laser communication between satellites in orbit with optical inter-satellite link (OISL) technology.

The demonstrator satellites were launched in June 2023 and are capable of almost instantaneous transmission of data via laser transmission from a distance of 5000 kilometers.

“Precisely pointing two satellites, across distances equivalent to New York to London, and establishing an inter-satellite optical link is a significant milestone for Spire,” said John E. Ward, senior director of research & development at Spire Global.

Spire claims to have compartmentalized a system the size of a microwave down to the size of a tissue box, a SWaP advantage that will support their goals of serving weather forecasting, remote sensing for navigation and environmental monitoring, and other global communications services.

“Our OISL payload is the smallest on the market, allowing us to deploy this technology on our small satellites while delivering performance previously achievable only with much larger systems,” said Thomas Carroll, team lead of the applied optics team at Spire Global.

Spire’s OISL technology was supported by funding from the UK Space Agency as well as a European Space Agency (ESA) Advanced Research in Telecommunications Services (ARTES) pioneer partnership project inside ESA’s connectivity and secure communications directorate.

Spire plans to launch four additional Low Earth Multi-Use Receiver (LEMUR) satellites to replenish its constellation no later than March 2025, and following this successful optical demonstration, another three LEMUR satellites with OISL technology later in 2025, two of which with Exolaunch on the Transporter-13 rideshare mission with SpaceX.

Founded in 2012 as NanoSatisfi Inc., the NYSE-listed company also operates a fleet of more than 110 CubeSats, which provide data services such as positioning and weather information. It operates a network of more than 30 ground stations globally.

Inter-satellite optical history

The company isn’t unique in its interest in optical inter-satellite communications, with landmark and wide-scale development being prevalent in the 2010s.

The European Space Agency demonstrated the world’s first laser inter-satellite link in November 2001 between their satellite Artemis and the French space agency’s SPOT 4.

Groups like Mynaric, OneWeb, and Kepler have invested similarly in the technology, with comparable milestones over recent years, and SpaceX started launching laser-equipped Starlink satellites as of September 2021. Optical crosslinks between the satellites of a LEO constellation reduce reliance on the networks of ground stations, adding to the resilience of its connectivity.

In 2023, Northern Sky Research’s senior analyst Prachi Kawade predicted the revenue generated from laser communication terminal (LCT) sales between the years of 2022 and 2032 would equal $2.6 billion, growing at a compound annual growth rate of 67.3 percent.

The optical advantage

Optical inter-satellite communications offer an advantage against radio frequency connections due to higher throughput at multiple gigabits per second, higher security with lower risk of interception, freedom from the congestion of radio bands and regulatory licensing, and greater cost efficiency due to better data rates making for lower cost per bit.

A downside is that since optical alternatives are newer, there is less technological standardization, meaning it’s less likely inter-satellite links can communicate with satellites of other operators or be backward-compatible with older optical systems. This is a problem that the US Defense Advanced Research Projects Agency (DARPA) has attempted to address with its Space-BACN program since 2022.