High Gain Antenna Gimbal (HGAG) for the rover Perseverance of the Mars 2020 mission
Proba-3 is ESA’s first precision formation flying space mission. The objective is to demonstrate how small satellites, in combination with formation flying technology, can achieve relevant scientific goals and perform scientific measurements not possible otherwise.
This technology—a combination of small independent platforms—is easier to launch and can replace bulky structures, such as telescopes, and work as a single entity while achieving high performance. The application of formation flying technology would be of great interest in a wide range of missions, including X-ray astronomy and optical or IR interferometry missions.
The two Proba-3 satellites will demonstrate the readiness of such technology by performing in orbit a set of typical formation flying operations: station-keeping at different relative distances (from 25 m up to 250 m); approaching and separating in precise formation without losing millimetre precision; repointing the formation as a virtual rigid body away from the Sun and the combination of station-keeping, resizing, and re-targeting manoeuvres.
Proba-3 is not only a technology demonstration mission. It will also perform scientific observations, taking images of the Sun’s corona through a coronagraph instrument placed in one of the spacecraft. Formation flying technology entails placing one of the two Proba-3 satellites in front of the instrument’s lens, thus blocking out the Sun’s disk and creating an artificial eclipse in flight. Doing this in space, at a distance of 150 m, will achieve unprecedented performance in coronagraphy and, therefore, will bring highly valuable scientific outcomes.
Most of the operations in Proba-3 will be done fully autonomously, with no intervention from the ground to actively control the formation. The Proba-3 satellites will be able to coordinate their own operations based on a pre-defined timeline defining activities for the next days. They also must be able to take autonomous decisions in case of failures happening during such operations, breaking the formation and putting the satellites in a safe configuration until ground is able to further investigate the issues.
Proba-3 space segment is made of two satellites. The first one, called Coronagraph Spacecraft (CSC), contains the main instrument (coronagraph). The second satellite, called Occulter Spacecraft (OSC), carries an occulting disk that cover the Sun’s disk as seen from the other satellite. The OSC, as leading entity for the formation flying system, also integrates the main metrologies units used for formation flying, in particular a laser metrology system and a set of cameras part of a visual-based system. The two satellites are launched in stack configuration, the OSC mounted upon the CSC, with the solar array of the CSC stowed.
Proba-3 is part of ESA’s General Support Technology Programme (GSTP), with Spain and Belgium as main country contributors to the project.
Sener is leading as System Prime the Proba-3 mission, in close collaboration with a Core team consisting of Redwire Space, Airbus Defence and Space in Spain, GMV Space and Defence and SPACEBEL, each one bringing to the programme their expertise in their dedicated technical discipline. The whole industrial consortium, including sub-contractors, is made of more than 29 companies from 17 different countries.
As System Prime, Sener is responsible for the overall system design (covering the two Proba-3 satellites, the ground segment as well as the overall mission design) and coordinates the activities of the Core team. Sener is also in charge of the procurement of the metrologies used by the Formation Flying System.
Sener is also responsible for the design, manufacturing, and testing of the high-stability Optical Bench Assemblies (OBA) for the two spacecrafts. These benches ensure that the pointing of the different optical instruments and payloads of the satellites is controlled and very stable during the observation periods of the mission.
Finally, Sener has developed the mechanism used for the deployment of the solar panel of the Coronograph Spacecraft after launch, and has provided the S-band Low Gain Antenna used by Proba-3 Telemetry, Tracking, and Commanding subsystem.
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