Enabling RO-Based Sensing and Navigation on Metop-SG-A1

MetOp-SG-A1 overview

The MetOp-SG-A1 satellite was launched by an Ariane 6 rocket and hosts the Copernicus Sentinel-5 instrument. Comprising of A-type and B-type satellites, all equipped with advanced instruments, the MetOp-SG-A1 will deliver information for global weather forecasts, air quality and climate prediction for the next 20 years. The MetOp-SG-A1 is the first in a series of three pairs of satellites, the MetOp-SG-B1 will be launched next year. 

The MetOp-SG-A1 launch is an exciting milestone for meteorology, celebrating European engineering excellence and ESA's long-term strategic investment in enabling technologies. 

Enabling MetOp's navigation

One of the mission’s enabling technologies is the AGGA-4 Global Navigation Satellite System (GNSS) receiver chip – an Application-Specific Integrated Circuit (ASIC) chip. Developed for precise space applications, AGGA-4 enables continuous onboard availability of Position, Velocity, and Time (PVT) solutions for satellites, even in challenging environments.  

AGGA-4 also measures GNSS signal parameters that are used to determine the exact path the signals take through the atmosphere (from satellite to receiver). The sensor using AGGA-4 captures precise information about atmospheric temperature and humidity that influence the propagation path. 

Tech in-depth 

The AGGA-4 is a product of ESA innovation and the collaboration of industry, the ESA Earth Observation Envelope Programme (EOEP), Future Earth Observation Programme (FutureEO) and Technology Development Element programme (TDE), through the decades. 

A brief history: 

• The concept was started by ESA in the 1990s due to the inadequacy of existing European industry GNSS solutions. 
• The need to support precise orbit determination, radio occultation, and formation flying became the starting point for what was to come. 
• This led to the first prototype of a receiver and eventually to AGGA-0, a miniaturised digital GNSS processor. 
• To promptly deliver the processor as a space-qualified component, ESA took over chip development in-house, resulting in AGGA-2, which was widely used for missions like MetOp-GRAS, GOCE, Sentinels, and Radarsat-2. 
• AGGA-2’s success proved the value of mission-driven innovation and long-term investment through ESA programmes. 

AGGA-2 to AGGA-4

The evolution continued with AGGA-4. Developed under ESA's Earth Observation Envelope Programme (EOEP), now known as FutureEO, with the support of ESA’s General Support Technology Programme (GSTP), AGGA-4 was built on from AGGA-2 with major upgrades in performance, integration, and GNSS capability.  

The key focus for AGGA-4 was enhanced radio occultation (RO) and precise orbit determination (POD). The upgraded AGGA-4 also demonstrates technologies that enable faster processing and lower power consumption. Making the chip ideal forMetOp-SG’s GRAS-2 sensor, the Radio Occultation (RO) instrument, will deliver high-accuracy atmospheric profiles via GNSS radio occultation. This is critical for weather forecasting and climate monitoring. 

AGGA-4's s high sensitivity and multi-constellation support also improves the suitability for autonomous orbit raising of geostationary satellites – an increasingly important capability for future missions.  

The fundamental semiconductor technology for the AGGA-4 chip was developed within ESA’s Technology Development Element programme (TDE). 

ESA’s hands-on role

ESA’s technology experts were dedicated to the progressive development of AGGA-4 – working on the design's source code and CAD infrastructure for the Microelectronics Lab, contributing ESA-owned IP like the LEON2FT processor, and supporting industry solutions. 

The AGGA-4 is just one example of our ongoing investment in space-grade Application-Specific Integrated Circuit (ASIC) chips. ESA continues to empower this investment, now working on 7nm technologies under the Electrical, Electronic and Electro-mechanical EEE Space Component Sovereignty Initiative.