Spire Global, Inc., Virginia, United States
Keywords: Cube-Sat, LEO, RF, MDA, WeatherSpire Global, Inc designs, builds, owns, and operates a low earth orbit constellation of more than 60 3U CubeSats, as well as a global network of 29 ground stations with a real-time acquisition and processing system, and a cloud based data distribution service. The 3U satellite form-factor maximizes launch opportunities and supports a very rapid tech-refresh cycle. Spire’s satellites carry AIS, ADS-B, and GNSS-RO payloads. In addition to temperature, pressure, and water vapor profiles of the neutral atmosphere, the GNSS-RO payload also measures TEC; the line-of-sight integration of electron density from the Spire CubeSat to a GNSS satellite. Each Spire GNSS receiver (known as STRATOS) tracks GNSS signals through two antennas for radio occultation (RO) atmospheric retrieval. Using an open loop tracking technique, the receiver utilizes the limb-pointing RO antenna to track the GNSS signal phase during each occultation event as it is delayed (bent) by the atmosphere. The excess phase files then serve as the primary input to RO retrieval algorithms for estimates of atmospheric bending angle, refractivity and temperature. The observations are then used in numeric weather models to improve terrestrial and space weather forecasts.