AIS / Spire Sense
All large ocean-going vessels and passenger vessels are required by the International Maritime Organization to install an AIS transponder and broadcast information about their location and other particulars. Spire captures and decrypts the vessel transponder signal from its satellite constellation as well as land-based receivers. The data is cleaned, attached to specific vessel identifiers, and combined with other vessel-specific information to create a global database of ocean-going vessels that is updated on 15-minute intervals and enhanced through AI software.
ADS-B / Spire AirSafe
Commercial, military, business, and personal aircraft are facing new regulations that require the installation of ADS-B transponders by 2020. Most commercial and business jets are already equipped and regularly send information about their location and speed that Spire captures from its satellite constellation. Spire is at the forefront of space-based ADS-B collection and can track over the oceans, poles, and remote areas where ground-based receivers cannot be installed.
GNSS-RO / Spire Stratos
GNSS-RO is a technique that provides unique temperature, pressure, and moisture vertical soundings through the atmosphere, similar to the type of data collected by a weather balloon. Rather than data being available only twice per day from specific sites, GNSS-RO utilizes Spire's satellite constellation to collect soundings 24/7 on a global basis and over remote regions like the oceans and the poles. In addition to being an important input for weather forecasting, GNSS-RO is also a climate quality measurement.
GNSS-RO data is output using the BUFR format convention. BUFR files are a binary data format that include bending angle, refractivity, and dry temperature as a function of altitude during a radio occultation event. The three sets of profile information (bending angle, refractivity, and dry temperature) represent increasing levels of Spire processing of the excess phase measurements recorded by the CubeSat GNSS receiver. BUFR files are commonly used by the World Meteorological Organization (WMO) for ingestion into Numerical Weather Prediction (NWP) models for data assimilation, and radio occultation is one of several remote sensing datasets that can be converted into BUFR files to describe meteorological data. The BUFR files produced by Spire comply with the BUFR files produced by the COSMIC Data Analysis and Archive Center (CDAAC) for COSMIC radio occultation data products.
Total Electron Content
When the GNSS receiver on-board a Spire satellite is powered on, it continuously tracks multiple dual-frequency GNSS satellite signals simultaneously from the POD antenna. These signals are primarily used for the purpose of precise orbit determination, which is necessary for neutral atmospheric radio occultation inversion. However, the pseudorange and carrier phase measurements measured by the receiver are also used to derive an estimate of the ionospheric total electron content (TEC) along the line-of-sight to each GNSS satellite. During post-processing, the TEC is computed for each signal "arc" (i.e. the period when the Spire receiver is continuously tracking a particular GNSS satellite) by forming a linear combination of phase measurements from dual GNSS frequencies. The phase TEC measurements are then "leveled" to the analogous combination of the pseudorange measurements for a more accurate measurement. Receiver and transmitter differential code biases are removed when possible.
The computed TEC values are stored in standard NetCDF format along with ancillary information including the transmitter and receiver positions. These data sets are packed in a NetCDF format, following conventions derived from data products created by CDAAC.
Ionospheric Scintillation Indices
Scintillation indices are indicators for ionospheric turbulence and are subdivided into two classifications: amplitude scintillation (S4), and phase scintillation (σɸ). Both provide indicators for "space weather" in the upper atmosphere. For example, large S4 values from a GNSS link may indicate ionospheric "storms" consisting of electron density gradients (e.g., Equatorial Spread F). This could lead to loss-of-lock on GNSS receivers, jeopardizing a receiver's ability to provide robust and accurate Position, Navigation, and Timing (PNT). Continuous monitoring of scintillation indices is key for understanding GNSS link health, and is a first step toward predicting potential GNSS regional outages.
Spire's CubeSats feature an advanced scintillation monitoring capability and can measure both amplitude and phase scintillation (S4 and σɸ). Combined with both a large constellation (~100 CubeSats) and diverse orbital planes, Spire's constellation is prepared to contribute critical ionospheric data, particularly over Equatorial regions.
These data sets are packed in a NetCDF format, following conventions derived from data products created by CDAAC.
Magnetometer data is collected continuously on Spire spacecraft as part of our Attitude Control and Determination (ADCS) system. The sensor used is based on magneto-inductive technology to deliver high-performance resolution and repeatability with high gain, high sample rates, low hysteresis, and no need for temperature calibration.
Spire can provide the magnetic field vector (x, y, z + unix timestamp) Unit: nT. The time resolutions is 4 Hz or 0.1 Hz.