focuscn is a member of GMV's focussuite and brings to satellite operators a solution to the domain of flight dynamics operation of constellations. focuscn is a completely integrated application that provides full life cycle support of a satellite constellation through an unsurpassed collection of mission independent and mission specific functionality that brings to satellite operators a perfect combination of professional off-the-shelf solutions with the flexibility and customer focus of a world leading supplier of flight dynamics custom solutions. Computational layer is based on the extensive reuse of existing operational flight dynamics systems and mission analysis tools devoted to constellation design, optimization and control. It inherits GMV’s vast experience with constellations flight dynamics software packages. It supports currently the Galileo, Globalstar and O3B constellations. Most of the routine tasks and operations are automated through the use of autofocus component. focusCN is able to support different constellations sharing data between them.
Flight Dynamics Functions Supported by focuscn computational Layer
Mission Specific Functions
Providing full lifecycle support of the corresponding satellite platform with a degree of accuracy 100% compatible with native systems focusCN supports all mission specific needs, such as:
- Maneuver Implementation
- Fuel Mass Evolution
- Station Keeping Maneuver Preparation
- De-orbiting maneuvers computation
- AOCS support functions
- Contingency support functions
- Attitude Determination and Propagation
Mission Independent Functions
- Ingestion of Solar Flux Data and Earth Observation
Modules in charge of ingesting in the system the Solar flux data, Earth Orientation parameters and leap seconds information generated by External Agencies.
- Pre-Processing of Tracking Data
This module ingests and pre-process input tracking data. It ingests the raw tracking data, soothes, reduces it, and applies calibration. It supports currently the ingestion of GPS data, range, Doppler, azimuth and elevation.
- Orbit Determination and Maneuver Estimation
This module provides estimations of the spacecraft orbit that are more accurate than the predictions generated from previous orbit reconstructions.
The resulting orbit is uniquely defined by:
- An initial state vector
- An initial epoch
- The list of force models applied
- Parameters associated with these models (extended state vector)
It is able to estimate all arc-dependent parameters required including:
- Scale factors for S/C maneuvers
- Aerodynamic force coefficients for each S/C and per arc
- Radiation pressure coefficients (solar radiation) for each S/C and per arc
- Bias per different altimeter on the altimetry measurements
- Station biases per arc and per pass
- Tracking station positions
- Station parameters per pass or per time interval
- Pass and arc parameters for the same station in the same run
The Orbit Determination component is also responsible of calibrating the maneuvers from the tracking data. For several revolutions after the maneuver(s) have been performed, a calibration run is executed. This activity will continue until sufficient measurement data have been accumulated before and after the maneuver to provide accurate estimations of both the spacecraft motion and the maneuver calibration factors.
The Orbit Determination component shall take advantage of the Orbit Propagation component to propagate the orbit within the orbit reconstruction period. This ensures that the orbit modeling is consistent between reconstruction and prediction.
- Orbit Propagation
This module computes the evolution of an orbit forward and backward in time. It supports the propagation of impulsive and long maneuvers. The force model used by this module is fully configurable by the operator. The algorithms and models have been implemented to make the system compliant with the latest recommendations of the International Earth Rotation Service (IERS) standards.
- Events Generation: This module generates the geometrical events:
- Ascending and descending node crossing times.
- Apogee and Perigee crossing times.
- Umbra and penumbra crossing times of Earth and Moon eclipses.
- Sun and Moon AOS/LOS for a Sun sensor
- Sun and Moon AOS/LOS for an Earth sensor
- Sun-Satellite-Earth Colinearity
- Sun-Satellite-Station Colinearity
- Station visibilities.
- Satellite local time
- Constellation Control: It incorporates a set of software modules implementing the following:
- Station keeping: it implements relative and absolute station keeping control techniques. It is in charge of defining maneuver sequences that minimize the fuel consumption considering the applicable constraints.
- Satellite relocation.
- Satellite disposal.
- Replacement strategy
- End of Life estimation functions
- Antenna Pointing Elements: A set of modules are available to generate antenna pointing elements in different formats
- Two Line Elements (TLE) Management: A set of modules are available providing the following functionalities:
- Ingestion of NORAD TLE database and generation of internal orbit file for the requested satellite.
- Generation of satellite TLE set
Databases supported by focusCN
- Central Body: It contains the definition of different geophysical models used by the system, i.e. nutation model, Gravity Field Model, Dynamic Solid Tide Model,…
- Tracking Stations and Tracking Sites: It contains data related to ground-stations used for tracking purposes and corresponding sites
- Constellations: It contains the definition of a constellation of satellites, in terms of number of satellites, number of orbital planes, reference orbital elements, reference position of the satellite in the plane,…
- Satellites: It contains satellite-specific data, such as its identifiers, mass and radiation and aerodynamical coefficients
- Transponders: It contains data relative to on-board tracking instruments and transponders
- Thrusters: It contains the data relative to the thruster equipment of the satellites, including, among others, thruster alignment, specific impulse and characteristic durations
- Instruments: It contains basically the location and data that define the different parameters of the sensors modeled by the FDS (generic sensors with pyramidal and conical field of view), wheels, gyroscopes.