Euclid: Mission and Importance

Mike Lundy, Project/HR Managing Intern

4.5 minute read

Euclid Space Telescope

Launch Day: July 1, 2023

Launch Vehicle: SpaceX Falcon 9

Orbit: Lagrange Point L2

Mission Life: 6 years

Euclid mission launch aboard SpaceX Falcon 9, July 1, 2023

The launch of the Euclid Space Telescope this past July is yet another example of humanity’s ever-expanding abilities to explore our universe. Euclid has a unique and difficult mission ahead that will provide remarkable insights into some of the most burning questions in the science community. The telescope will seek to advance our knowledge in the realms of dark matter, dark energy, gravity, and the expansion of the universe, among others.

The European Space Agency (ESA) has sent the telescope out to:

“explore the composition and evolution of the dark Universe. The space telescope will create a great map of the large-scale structure of the Universe across space and time by observing billions of galaxies out to 10 billion light-years, across more than a third of the sky. Euclid will explore how the Universe has expanded and how its structure has formed over cosmic history, revealing more about the role of gravity and the nature of dark energy and dark matter.”

Euclid will orbit Lagrange Point L2 for the next six years to try to answer these questions and expand our views and understanding of the universe.

The importance of Euclid can not be understated, as the mission will spend its time solving essential universal mysteries. Using 3D mapping, Euclid will observe a third of the sky and billions of galaxies as far back as 10 billion light years. This process will observe the expansion of the universe and hopefully provide invaluable information in regard to the speed at which the universe is expanding and how it has changed over time. In the 1920s, astronomer Edwin Hubble discovered that the universe was expanding, and from the 1920s until the 1990s it was thought that the gravity of matter would slow the expansion of the universe. In 1998, using observations of a Type Ia supernova, two teams of scientists were able to determine that the expansion of the universe is in fact not slowing down, but speeding up! It has been theorized that the force behind the universe’s accelerated expansion is an as yet unknown form of energy, “dark energy,” the further understanding of which is one of the main scientific objectives of the telescope. Furthermore, Euclid's astronomical mapping will provide information on the history and structure of the Cosmic Web, which is the placement of galaxies and their interconnectedness through strands of gasses and dark matter that are not observable to the naked eye.

Illustration of Euclid Mapping a third of the sky

The observation of the “dark side” of the universe or that of dark matter and dark energy is perhaps the most challenging aspect of Euclid's mission. Considered “dark” because the matter does not interact with the electromagnetic force and therefore cannot be observed through its interactions with light, it will be crucial for Euclid to expand knowledge on this subject. As obvious as matter is, consisting of what we can see, such as planets, stars, people, etc., it only makes up between 1% to 10% of the universe. Scientists believe that dark matter, on the other hand, could make up anywhere from 30% to 99% of the universe. This is extraordinary when you sit back and think about it. All of what we can see may only be 1% of everything there is! The other aspect is the study of dark energy. This may be the key to understanding not only the expansion of the universe, but also the acceleration of that expansion. An understanding of our universe’s accelerated expansion may provide scientists needed information on what that expansion means. Is there an end to the expansion or will it go on forever, and what happens if it does not? Euclid's observations and data will provide insight for scientists and hopefully fill in some missing details and information about the theory of the Big Bang. During the course of Euclid’s six year mission it is the hope of the ESA and its partners that a great deal of information will be attained and that the discoveries and observances will bear fruit to a majority of these theories.

Perhaps some of the most important observations Euclid will assess are our theories of gravity. We all understand gravity in the simplest terms and in the way Newton explained them - as the force that holds our feet to the ground. Others, not me until recently, understand gravity as a more complex theory, which is that of Einstein's theory of General Relativity. Einstein theorized that gravity is more of a consequence of mass bending space-time rather than a force of attraction between objects.

As a simplified example, I think back to elementary school and the parachute game. My class and I would stand around a colorful parachute and throw balls and other objects into the pulled chute. The heavier more dense items would weigh down the fabric and the lighter less dense items would move toward the heavier ones. Of course, this would only last until we all started shaking the parachute as hard as we could to make the objects fly all over the place. Obviously, Einstein's theory of General Relativity is much more complex than the parachute game, but the example does lend a visualization to how gravity operates in his theory. In Einstein's theory, gravity is viewed as a dimension rather than a downward force that acts on matter. As General Relativity is generally accepted and has been confirmed time and time again, it will be of great interest to see how the theory holds up after Euclid scans and interprets massive distances and times in the universe. Will Euclid's explorations and data solidify Einstein's theory or will scientists have to return to the drawing board? More importantly, Euclid is providing researchers and scientists the opportunity to continue searching for knowledge and answers to some of the universe's greatest questions.

Beyond the listed aspects of Euclid's mission, the telescope will also provide scientists with abilities to study a wide range of other theories and questions ranging from supermassive black holes at the center of galaxies to the existence of primordial black holes. ESA’s Euclid mission is exciting for astrophysicists and astronomers and their respective fields, but it is also incredibly important for our understanding of the universe as a species. Gaining further knowledge about space aids the development of humanity, whether technologically or otherwise. Missions like this one and that of the James Webb Space Telescope or Gaia Space Observatory could provide insights that lead us to a future with interstellar travel and the expansion of humankind into the furthest reaches of our galaxy and beyond.

Recommended column to read next: Space Questions for the Everyday - Volume II