Vigil Space Weather Mission - Space Segment

The ESA Vigil Mission, formerly known as Lagrange, will launch by end of 2029 (planned date at the time of preparation of this abstract) Spacecraft towards the 5th Sun-Earth Lagrangian point (SEL5) to perform continuous observations of the Sun and the space between the Earth and the Sun, to provide measurement data for space weather nowcasting and forecasting and for event-based warnings and alerts when solar events take place. The observations from SEL5 will enable more accurate space weather impact predictions and early warnings of potentially hazardous solar weather conditions emerging. Vigil mission will provide space weather observations for operational applications, the Space segment is required to carry out observations at all times including severe space weather events.

The field of view from SEL5 allows monitoring of the onset of Coronal Mass Ejections (CMEs) from a different angle than coronagraphy from the Sun-Earth line. Vigil mission will also monitor the entire space between Sun and Earth for mid-course tracking of solar wind features, including CMEs as they travel towards Earth. Vigil will provide fresh solar magnetic field data for numerical solar wind models used in CME propagation estimation and enable more precise predictions of the CME arrival times on Earth. Magnetograph data are also expected to improve the solar flare and CME onset forecasting accuracy. In-situ measurements in SEL5 will allow monitoring of high-speed solar wind streams several days in advance before they rotate towards the Earth.

The Vigil Space Segment under Airbus Stevenage Prime is largely based on Airbus Astrobus products for the key platform elements and carries a Payload Suite comprising of three remote instruments:

• the Compact Coronagraph (CCOR) from Naval Research Laboratory (USA)
• the Heliographic Imager (HI) from Leonardo SpA
• the Photo-Magnetospheric field Imager (PMI) from Max Planck Institute in Gottingen

Two in-situ instruments:

• the Plasma Analyser (PLA) from Mullard Space Science Laboratory in London
• the Magnetometer (MAG) from Imperial College London

In the frame of the inter-agency cooperation between ESA and NASA, Vigil will offer the possibility to accommodate an additional instrument NASA instrument of opportunity (NIO), still under selection at the time of presentation of this abstract.

The Space Segment is designed for 7.5 years life-time (with a possible extension by 5 years) and high availability (98.5%). The on-board latency is instrument dependant and ranges from 2 (MAG/PLA) to 65min (HI-2). This performance is achieved through a permanent and real-time X-band communications sub-system.

The Space Segment is compatible with Ariane 6 and Falcon 9 launcher. After launch, the transfer to SEL5 is achieved within 46 months. Operations are starting 27 month after launch, once Earth separation is above 30°, to maximise the operational return of the mission.