ESA is offering access to Global Navigation Satellite System data in a new Announcement of Opportunity for Spire. 

The Spire Global constellation consists of almost 100 nanosatellites operating in Low Earth Orbit, which provide radio frequency monitoring for many applications, including maritime and aviation tracking, weather forecasting, and measurements of Earth’s atmosphere and ionosphere. New satellites are launched on an annual basis to maintain the constellation’s high revisit rate and global coverage.

Spire provides Global Navigation Satellite System (GNSS) data from the STRATOS instrument to ESA’s Third Party Missions programme. The Third Party Missions programme consists of more than 50 international missions, data from which are accessible free of cost for research and application development. 

STRATOS collects rising and setting radio occultation (RO) signals transmitted by GNSS satellites, such as GPS and Galileo. These radio occultations are used to determine temperature, pressure, and humidity profiles of Earth’s atmosphere, which provide valuable data for weather forecasting. 

The new Announcement of Opportunity for Spire focuses on encouraging innovative projects using GNSS data and Polarimetric Radio Occultations. Three datasets are available:

• Polarimetric Radio Occultations (PRO) – Consisting of PRO measurements from 15 May to 30 November 2023. PRO measurements observe the properties of GNSS signals as they pass through Earth’s atmosphere. The polarisation of the signals is recorded separately for horizontal and vertical polarisation to provide information on the anisotropy of hydrometeors along the signal’s propagation path. These measurements add sensitivity to ice and precipitation content, along with traditional RO measurements of atmospheric temperature, pressure, and water vapour.
• Near-Nadir GNSS Reflectometry (GNSS-R) – Consisting of Near-Nadir GNSS-R measurements from 25 January to 24 July 2024. Near-Nadir GNSS-R measurements track surface reflections observed by the near-nadir pointing GNSS-R antennas onboard the satellites. Using Delay Doppler Maps, these surface reflections can be used to measure ocean surface winds and characterise land surfaces for many applications, including soil moisture, freeze/thaw monitoring, flood detection, inland water body delineation, and sea ice classification.
• Grazing angle GNSS Reflectometry – Consisting of grazing angle GNSS-R measurements from 25 January to 24 July 2024. Grazing angle GNSS-R measurements track surface reflections using the limb-facing RO antennas onboard the satellites. The grazing angle data can be used to characterise land surfaces for many applications, including sea ice classification, freeze/thaw monitoring, inland water body detection and delineation. The data also measure relative altimetry with decimetre-level precision for inland water bodies, river slopes, sea ice freeboard, and water vapour characterisation from tropospheric delays.

Access to the data requires submission of a Project Proposal, which will be evaluated by ESA and Spire.

The opportunity is open until 31 March 2025 

Go to the Announcement of Opportunity page to learn more and submit your proposal.