This artist’s representation depicts the journey of Euclid, departing Earth and heading towards the Sun-Earth Lagrange point L2. This point of equilibrium in the Sun-Earth system lies 1.5 million kilometers away from Earth, opposite the Sun. As Earth orbits the Sun, so does L2. During Euclid’s orbit around L2, its sunshield constantly blocks light from the Sun, Earth, and Moon while its telescope is aimed at the deep space, maintaining high instrument stability. Credit: ESA
Contrary to the notion that an orbit can only be maintained around a physical entity with significant mass, such as a star or a planet, it’s indeed possible to orbit around an infinitesimal, invisible point— a force oasis. The ESA’s Euclid mission was launched on July 1, 2023, tasked with unravelling the mysteries of the dark universe, with its target being the frequently chosen astronomical mission site, Lagrange point 2.
The subsequent animation, developed via “Gaia Sky,” illustrates Euclid’s trajectory from Earth to this distinctive and beneficial space position. The second Lagrange point (or Libration point), situated about 1.5 million kilometers away from Earth, opposite the Sun, is roughly four times more distant than our Moon.
Euclid took about a month to reach ‘L2’, where it recently arrived and will stay for an estimated six years in orbit. From L2, it will probe the enigmatic nature of dark matter and dark energy that constitute 95% of our Universe, yet remain largely unexplored.
What are Lagrange points?
Lagrange point 2 is one of the five Lagrange points, in fixed positions around the Sun and Earth. These points are infinitesimal and invisible, created where the gravitational force of two large bodies produces a ‘centripetal force’ that enables an object to rotate alongside them at these locations.
The balance between the ‘push’ and ‘pull’ forces results in five gravitational oases near any two massive moving bodies. Therefore, satellites orbiting around Lagrange points require less effort and fuel to maintain their position.
In a perfect world, spacecraft would perpetually stay in orbit here without any assistance. However, real-world factors, such as our Sun’s ‘breathing’ — the Solar Radiation Pressure — can cause spacecraft to drift. To maintain Euclid’s orbit, ground controllers at ESA’s mission control center in Germany will command a minor maneuver every four weeks.
Why ‘L2’?
The second Lagrange point is perfect for astronomical missions as it allows them to keep the Sun, Earth, and Moon at their back, preventing observational interference while providing a clear view of the deep space and ensuring communication with Earth.
At L2, Euclid joins ESA’s Gaia mission and the ESA/NASA/CSA James Webb Space Telescope, each following distinct trajectories. This location’s continuous sunlight on Euclid keeps the telescope thermally stable, allowing the instrument to achieve the high stability required for long exposure observations.
Euclid’s orbit around Lagrange point 2 is significant, larger than the Moon’s orbit around Earth. The ‘radius’ of Euclid’s orbit ranges from about 400,000 kilometers at its closest to the center, to up to 800,000 kilometers at its furthest. This large orbit requires minimal fuel to reach and maintain, making it more efficient.
How will Euclid’s mission end?
Despite being far from Earth, the second Lagrange point is still considered an Earth orbit, thus subject to international regulations regarding space sustainability.
Aligned with its Zero Debris commitment, ESA has planned a disposal maneuver for Euclid at the end of its mission, directing it into a heliocentric orbit – the same as Earth’s around the Sun. For at least 100 years, Euclid’s chance of re-entering the Earth-Moon system will be extremely slim. By then, its valuable metals may be repurposed in space!
Euclid is ESA’s fifth mission at Lagrange point 2, joining the Gaia observatory, and NASA/ESA James Webb Space Telescope, while following Herschel and Planck’s orbits, all aimed at illuminating the enigmas of our Universe.
Gaia Sky is an astronomy visualization software, capable of producing real-time, 3D visuals. It’s compatible with Windows, Linux, and macOS, and was developed as part of ESA’s Gaia mission, which aims to map around 1 billion stars of our Galaxy. The Gaia group of the Astronomisches Rechen-Institut (ZAH, Universität Heidelberg) developed it.
Table of Contents
Frequently Asked Questions (FAQs) about Euclid mission
What is the Euclid mission?
The Euclid mission is an initiative by the European Space Agency (ESA) that was launched on July 1, 2023. It was designed to study the mysterious nature of dark matter and dark energy that make up 95% of our Universe. Euclid is currently orbiting the Sun-Earth Lagrange point L2, a point of equilibrium in the Sun-Earth system.
What are Lagrange points?
Lagrange points are locations in space where the gravitational forces of two large bodies, such as the Earth and the Sun, balance out the centrifugal force felt by a smaller object, such as a satellite. This balance allows the satellite to essentially ‘hover’ in place relative to the larger bodies. The Sun-Earth system has five such points, labelled L1 to L5.
Why is Euclid orbiting the second Lagrange point (L2)?
L2 is an ideal point for astronomy missions. It allows spacecraft to keep the Sun, Earth, and Moon behind them at all times, preventing observational interference. This position also provides a clear view of deep space and maintains a direct line of communication with Earth.
How will the Euclid mission end?
At the end of the mission, in compliance with international regulations and ESA’s Zero Debris commitment, Euclid will be directed into a heliocentric orbit, essentially orbiting the Sun in the same path as Earth. This will minimize the likelihood of Euclid re-entering the Earth-Moon system for at least 100 years.
What other missions have orbited Lagrange point 2?
Euclid is ESA’s fifth mission at Lagrange point 2. Other missions include the Gaia observatory, NASA/ESA James Webb Space Telescope, and the orbits of Herschel and Planck. These missions are all part of ongoing efforts to explore the mysteries of the universe.
More about Euclid mission
- European Space Agency (ESA)
- ESA’s Euclid Mission
- Lagrange Points: Parking Places in Space
- Understanding Dark Matter and Dark Energy
- Gaia mission
- James Webb Space Telescope
6 comments
Just fascinating… We humans are tiny, but look at what we can do in space. Makes you think…
man, dark matter and dark energy are such mysteries. Hope Euclid can give us some answers.
Are they seriously already planning how to dump the thing when it’s done? Talk about forward thinking!
i always wondered how these crafts stayed in place up there… so its all bout balance, huh? Who’da thought.
So cool to think we’re orbiting around a point, not a planet or a star! Euclid mission rocks!
Cant believe euclids made it all the way to l2. Science, you never cease to amaze!