ESA Vigil

The European Space Agency’s (ESA) Vigil mission, formerly known as Lagrange, is a planned solar weather mission. Under this mission, two spacecraft will be stationed at the Lagrangian points L1 and L5, respectively.


  • It’s the first of its kind mission, with the aim of monitoring the unpredictable and active Sun and help protect the Earth from its outbursts.
  • Solar flares, coronal mass ejections, geomagnetic storms, solar proton events, and other space weather incidences will be monitored by ESA Vigil.
  • Monitoring of the space incidences will help in predicting the timing of its arrival on Earth and any effect it might have on infrastructure.

The objective of this Mission

This mission plans to position two spacecraft in the L1 and L5 Lagrangian points, where gravitational forces interact to provide a stable region where propellant may be saved and observations can be made. Since L1 is located in the solar wind ‘upstream’ from Earth measurements at the L1 will provide information about the space weather approaching Earth. The L5 point, on the other hand, allows the tracking of coronal mass ejections (CMEs) from the side in order to assess their speed and direction.

At L1, the spacecraft will measure the density, speed, dynamic pressure, and temperature of the solar wind, as well as the charged particle environment and the strength and direction of the interplanetary magnetic field. At L1, the spacecraft would also observe the solar disk and corona and will measure solar energetic particles that could be linked to solar flares and the start of coronal mass ejections.

By providing a side-view of the propagation of plasma clouds released by the Sun toward Earth, the spacecraft at L5 would complement the measurements made from L1.

At L5, the spacecraft would conduct measurements of the interplanetary medium and monitor the solar disk and corona.

What are Lagrange Points?

The gravitational forces of a two-body system, such as the Sun and the Earth, produce enhanced regions of attraction and repulsion at Lagrange Points in space. Spacecrafts use these points to reduce the amount of fuel needed to remain in position. Lagrange points are named after Josephy-Louis Lagrange, an Italian-French mathematician.



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