Astrogate Labs Develops Indigenous Optical Link for India’s Future Satellite Constellations

Bengaluru-based Astrogate Labs is developing an indigenous Optical Inter-Satellite Link terminal that would allow satellites to exchange large volumes of data directly through laser beams instead of routing every transmission through ground stations.

The company unveiled its OISL capability at Bengaluru Space Expo 2026 on September 8 and is targeting flight readiness in 2027. Astrogate describes the programme as India’s first indigenous development of an optical inter-satellite terminal.

At the same exhibition, the company demonstrated AstroLink Micro, a 10 Gbps laser communication terminal developed for space-to-ground links. AstroLink Micro and the new OISL programme are related technologies, but they should not be confused: the 10 Gbps terminal displayed at Bengaluru is currently a satellite-to-ground system, while the new programme extends Astrogate’s technology towards satellite-to-satellite communication.

Astrogate says its existing space-to-ground laser communication terminals have reached Technology Readiness Level 8, meaning the system has progressed to a flight-qualified level. The company also says it has supplied an indigenously developed satellite-to-ground laser communication terminal to ISRO. That particular customer relationship has been stated by Astrogate; ISRO has not separately announced the transaction in a public release that I could locate.

The significance of the new development becomes clearer when viewed against ISRO’s own plans for optical communications.

In June 2026, ISRO’s Space Applications Centre issued an Expression of Interest exclusively to Indian industry for indigenous Optical Communication Terminals for Low Earth Orbit and Geostationary Earth Orbit satellites. The document states that ISRO’s current and future programmes will require multiple optical terminals capable of establishing high-speed links between LEO satellites, between LEO and GEO spacecraft, and between satellites and the ground.

ISRO’s requirement therefore goes well beyond a single experimental laser link. It points towards a future satellite architecture in which spacecraft exchange data with one another as part of a network.

Why satellites need to talk directly to each other

Most satellites traditionally send collected information to a ground station when they pass within its field of view. The ground network receives that information and routes it to its destination.

That arrangement works well for conventional missions, but it becomes increasingly cumbersome when dozens or hundreds of satellites operate as a constellation.

An Earth-observation satellite, for example, may photograph an area while it is thousands of kilometres from the nearest suitable Indian ground station. It may have to store the imagery onboard until its orbit brings it over a station that can receive the data.

An inter-satellite link changes that arrangement.

The spacecraft could instead transmit the information to another satellite. That satellite could pass it to another spacecraft, or potentially to a higher-orbiting relay satellite with a suitable connection to the ground.

The data can therefore travel through space rather than waiting for the original satellite to fly over a receiving station.

ISRO itself identifies this as one of the advantages of optical inter-satellite communications. Its June EOI notes that such links can reduce dependence on RF ground stations and improve continuity of service for future LEO constellations.

For Earth observation, weather monitoring, disaster management and other time-sensitive missions, reducing the delay between collecting information and delivering it to users can be as important as improving the resolution of the satellite itself.

Why use lasers instead of radio?

Satellite communications have traditionally relied heavily on radio-frequency links.

RF systems are mature and reliable, but available spectrum is limited and tightly regulated. The amount of information generated by modern satellites is also increasing rapidly as imaging sensors produce higher-resolution photographs, radar products and other large datasets.

Optical communication shifts much of that traffic to laser wavelengths.

ISRO says optical terminals can provide data rates in the gigabits-per-second range and identifies increasing RF spectrum congestion as one reason for developing free-space optical communication.

A laser beam is also extremely narrow compared with conventional radio transmissions. That permits high data rates without requiring the same type of RF spectrum allocation.

But laser communications create their own engineering problems.

The terminals must point at each other with extraordinary accuracy. Two satellites travelling at several kilometres per second must first locate one another, acquire the optical signal and then keep their laser beams aligned while both spacecraft continue moving.

This process is known as Pointing, Acquisition and Tracking, or PAT.

ISRO’s current industry requirements specifically identify ultra-stable pointing, spacecraft-platform stability, thermal stability and PAT performance among the issues that must be solved for future optical terminals.

That is one reason an inter-satellite terminal is considerably more demanding than simply placing a laser transmitter aboard a spacecraft.

Links across thousands of kilometres

The distances involved are substantial.

ISRO’s June EOI envisages optical links of up to 8,000 kilometres between LEO satellites and as much as 45,000 kilometres between LEO and GEO spacecraft. It also examines GEO-to-GEO links over much greater distances.

Maintaining an optical connection over such ranges requires precision optics, stable spacecraft pointing, sensitive receivers and sophisticated control software.

Unlike a terrestrial fibre-optic cable, there is no physical medium guiding the beam between the transmitter and receiver. The light travels through free space, and the receiving spacecraft must remain inside an extremely narrow optical path.

Astrogate’s move from space-to-ground communication to OISL is therefore an important technical step. The underlying laser communications knowledge carries over, but satellite-to-satellite operation introduces a different tracking and relative-motion problem.

The company plans to bring the OISL terminal to flight readiness in 2027. The next decisive milestone will be an in-orbit demonstration showing that two spacecraft can acquire and maintain an optical link under actual orbital conditions.

What this could mean for Indian constellations

The immediate market for such a terminal is likely to come from the expansion of LEO satellite constellations.

A constellation equipped with inter-satellite links can operate more like a network than a collection of independent spacecraft.

An imaging satellite that has just collected data could pass it through neighbouring spacecraft until it reaches a satellite with access to a ground station. Broadband satellites could similarly hand traffic between one another as they cross different regions.

This is especially useful over oceans, polar regions and other areas where maintaining dense networks of terrestrial ground stations is difficult.

ISRO’s current requirements explicitly envisage LEO-to-LEO and LEO-to-GEO optical links, demonstrating that this type of architecture is already being considered for Indian missions rather than remaining a distant research concept.

There are also strategic applications.

Military and government satellite constellations increasingly depend on rapid movement of imagery, surveillance data and other information between spacecraft and users. An indigenous optical communications capability would give India greater control over a subsystem that could become increasingly important in future distributed space architectures.

That does not make an optical link inherently immune to interception or disruption, but its narrow beam and lack of dependence on conventional RF spectrum give it different operating characteristics from traditional satellite radio links.

Building the technology in India

Astrogate’s programme comes at a useful point in the development of India’s private space industry.

ISRO is actively looking for Indian companies capable of designing, manufacturing, integrating, testing and qualifying optical communication terminals. Its June EOI states that the exercise is intended to identify domestic suppliers capable of supporting current and future LEO and GEO satellite programmes. It does not guarantee procurement, but successful companies could eventually move into subsequent requests for proposals.

Astrogate therefore is not developing the technology in isolation from an identifiable domestic requirement.

The company already has experience with smaller satellite-to-ground terminals and says its hardware has undergone cross-compatibility testing with the University of Western Australia’s TeraNet mobile optical ground station.

Moving from that work to an orbital inter-satellite terminal is the harder engineering problem.

The real importance is not the laser itself. It is what happens when satellites no longer have to operate as isolated spacecraft waiting for their next ground-station pass.

An indigenous inter-satellite optical link would allow data to move across a constellation while it is still in orbit. For future Indian Earth-observation, communication and strategic satellite networks, that could substantially change how quickly information moves from a spacecraft to the people who need it.

---