PERSILS - PERSIstent Leo connectivity Service

Status date
Activity Code

Communications between satellites and Earth are usually performed by establishing a direct communication link between the in-orbit satellite and a ground station (GS) located on Earth’s surface.

Given the curvature of the Earth and the altitude of LEO satellites, a communication link can be established every 90 minutes for a duration of approximately 10 minutes. The limited availability of GS is a bottleneck for most LEO operators (including Aerospacelab), which need higher responsiveness for last-minute tasking orders, prompt collision avoidance manoeuvres, or instant transfer of compressed payload data packs.

For LEO satellite operators needing persistent Telemetry and Telecommand connectivity with their satellites, Aerospacelab’s PERSILS is the right solution, affordably unlocking new potential for operators and their customers.



The main challenges lie in the design and implementation of a solution yielding substantial improvements on LEO assets connectivity, while being: 

  1. Technically feasible

  2. Affordable to LEO smallsats operators

  3. With limited regulatory and technical burdens from a customer standpoint  

  4. Quickly operational (short time-to-market)


Although a topic of interest due to the rise in number of LEO satellites in operation, there is a very limited number of operational inter-satellite link solutions dedicated to commercial LEO operators on the market. The few are often prohibitively expensive from a small satellite philosophy perspective, which constitutes the core of the LEO market.

Furthermore, the technical burdens in the implementation of the solution are often a showstopper for operators.

Aerospacelab’s Ku-band terminal leverages existing GEO assets. This allows a short time-to-market, and limits frequency coordination problems.

Furthermore, as a microsatellite manufacturer, Aerospacelab is perfectly positioned to commercialize PERSILS terminals with no technical integration hurdles for the customer. Indeed, Aerospacelab intends to commercialize the solution as an option to its microsatellite platform package.

The terminals are additionally sold as standalone products to be integrated to third-party satellite platforms.


The two main components of the product are: 

  • A Ku-band terminal capable of communicating with partner’s GEO satellites from LEO with limited mass and volume, and a limited impact on LEO satellites regular commercial operations 

  • A yearly subscription for data relay through partner’s infrastructure

Together, these features yield significant connectivity improvements for LEO operators. 

System Architecture

The architecture of the project relies on a Ku-band terminal to be developed by Aerospacelab, for integration to its microsatellite platforms, as well as third-party satellites.

This terminal is used to communicate with GEO partner’s assets for TC and TM, which use traditional GEO infrastructure to constantly communicate with the ground.


The project is currently under a 6-months Definition phase, which support the characterization of technical, business, and regulatory aspects of PERSILS. Mission Analysis and Link Budgets were defined, as well as first versions of Business and Regulatory assessments submitted.

The Definition phase is due to be concluded in June 2022. If successful, Technology and Product phases are expected, to support the implementation of the solution. In orbit validation of PERSILS is anticipated by the end of 2023.

Current status

Currently under a 6-months Definition phase, PERSILS reached the MTR. Mission Analysis and Link Budgets were defined, as well as first versions of Business and Regulatory assessments submitted.

Aerospacelab interacts with its partner operating satellites in GEO to pinpoint the most suitable architecture from technical and business standpoints. Aerospacelab gathers Letters of Interest from LEO operators susceptible of using the solution once operational.

Prime Contractor