L2 Orbits of NASA's Webb Telescope & Europe's Euclid & Gaia Spacecraft

L2 Orbits of NASA's Webb Telescope & Europe's Euclid & Gaia Spacecraft

Nearly a month after its launch on July 1, 2023, the European Space Agency's Euclid spacecraft has travelled 1.5 million kilometers from Earth towards the Sun-Earth Lagrange point L2, meaning it has ‘arrived’ at its destination orbit. Euclid's mission is to explore the composition and evolution of the dark Universe. 

This animation showcases the orbits of Euclid (green), the James Webb Space Telescope (blue), and the Gaia mission (yellow) around this unique position in space. The positions of the spacecraft in this animation do not correspond to their current positions in space.

Located about 1.5 million kilometers from Earth in the opposite direction from the Sun, L2 is about four times further away than our Moon. Several other space missions like Webb and Gaia also orbit L2 as it offers the perfect vantage point to study the Universe.

At L2, the spacecraft can keep the Sun, Earth and Moon behind them at all times, so they do not interfere with observations, while at the same time getting a clear view of deep space and pointing an antenna back to Earth to remain in close communication.

Note: In celestial mechanics, the Lagrange points are points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies. Mathematically, this involves the solution of the restricted three-body problem.

Euclid and Webb’s halo orbit around L2 is big. In terms of distance, the ‘radius’ of Euclid’s orbit varies from about 400,000 kilometers at its closest to the center, and up to 800,000 kilometers at its furthest. By the time Euclid has completed one full revolution around L2, the Moon will have circled the Earth six times. Gaia orbits L2 in a Lissajous orbit, with a maximum distance of around 350,000 km from its center. Gaia's mission is to chart a three-dimensional map of our Galaxy, the Milky Way. 

Note: In orbital mechanics, a Lissajous orbit, named after Jules Antoine Lissajous, is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system with minimal propulsion.

The region around L2 is big and even though the orbits of these spacecraft seem to cross in the animation, in reality there is plenty of space and a collision can be easily avoided. For example, Webb and Gaia are between 400,000 and 1,100,000 km apart, depending on where they are in their respective orbits.

Video Credit: European Space Agency (ESA)/Gaia/DPAC; CC BY-SA 3.0 IGO

Duration: 2 minutes

Release Date: July 28, 2023

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