|Mission type||Space weather forecast|
|Start of mission|
|Launch date||2020s (if funded)|
|Rocket||L1: Vega C  |
L5: Ariane 6.2 
Lagrange is a 2018 concept study for a solar weather mission by the European Space Agency (ESA). This is a British-led concept that envisions two spacecraft to be positioned at Lagrangian points L1 and L5.
Monitoring space weather includes events such as solar flares, coronal mass ejections, geomagnetic storms, solar proton events, etc. Monitoring would help predict arrival times at the Earth and any potential effect on infrastructure. If funded, both Lagrange missions would launch in the 2020s.
To ensure an effective capability to monitor potentially dangerous solar events, ESA initiated a study of two potential future space weather satellites called Lagrange.. The Lagrange mission concept is overseen by the Space Situational Awareness Programme at ESA. On 2 February 2018, ESA signed technological contracts (Phase A) to be led by Airbus UK and OHB SE of Germany to design the spacecraft specifications and the instruments' integration process. UK's Rutherford Appleton Laboratory and Mullard Space Science Laboratory will assess the requirements of the science payload.
This mission concept proposes positioning two spacecraft in orbit at the L1 and L5 Lagrangian points, respectively, where gravitational forces interact to create a stable location to save propellant and from which to make observations. L1 is in the solar wind 'upstream' from Earth, so measurements at L1 provide information about the space weather coming toward Earth. In contrast, the L5 point provides a way to monitor coronal mass ejections (CMEs) from the 'side' in order to estimate their speed and direction.
The preliminary Lagrange mission objectives are: 
To achieve these objectives, the satellites at the L1 and L5 positions have to carry different types of remote-sensing and in-situ instruments. The suggested optical instruments take heritage from ESA and NASA science missions like SOHO, STEREO and Solar Orbiter, but the instruments would be optimized for operational space weather monitoring. The notional science payload may require: