A telescope that observes dark energy, is going to be launched soon

The universe is filled with planets, asteroids, black holes, and galaxies—each with their own set of mysteries. But one of the best concealed aspects of deep space lies in what scientists describe as dark universe. This is where dark energy and dark matter hide, interacting with the matter we can actually see. Scientists know very little about this dark side, other than that it is vast and it has shaped the evolution of our Universe—past, present, and future. And since we can’t see it directly, the hunt to understand dark energy and dark matter has taken decades. But ESA’s space telescope mission, named Euclid might just give us some answers. According to ESA, the universe is made of about 76% dark energy, about 20% dark matter, and 4% normal, or baryonic matter– which is the stuff that makes up you, me, and everything else we can see. When it comes to dark matter, we can infer its presence based on the gravitational effect on visible matter, and theories suggest that weak interacting massive particles, could lead to the answer. But as of right now, we just know that it exists.

“Dark energy” is another astronomical head scratcher. This term is used to explain the mysterious force that causes the rapid expansion of the universe. According to the theory of relativity, the gravitational attraction from all the matter in the universe should be slowing this expansion. But observations show that instead, it’s speeding up. In order to come to grips with this new realization, theorists have come up with other possible explanations for dark energy. Maybe the universe is filled with a strange energy-fluid, or it was the result of another version of Einstein's theory of general relativity that involves an equation that stops expansion altogether. Or parts of the theory of general relativity are wrong, and we need a new field that includes this acceleration. Which is why Euclid is so exciting.

This mission could piece together the puzzle that surrounds dark energy and dark matter, and ultimately help us understand how our universe works. ESA’s Euclid space telescope will map the geometry of the dark Universe and provide its cosmic history. Euclid will observe and analyze the shape and redshift of thousands of millions of galaxies spanning back 10 billion years. This will provide a large-scale 3D map that allows scientists to see how dark energy has played a significant role in the universe's expansion. And it will do this with a few key components. Other than the Silicon Carbide mirror that spans 1.2 meters in diameter, the telescope will be feeding two different instruments: a visible-wavelength camera and a near-infrared camera spectrometer.

These instruments will be pointed at more than one third of the entire sky Now you might be thinking, if Euclid can’t directly observe the dark universe, then what will its instruments be looking at? Well, the space telescope will be searching for a couple of cosmological ‘red’ flags. The first is weak gravitational lensing. In general, gravitational lensing is when the gravitational field of an object bends the light that passes by it. So, if we assume that dark matter is present, then astrophysicists can theorize that every galaxy we observe might be subject to a minute amount of gravitational lensing…approximately 1%.

This is the weak lensing and it’s what Euclid will be hunting for. Euclid is also going to be on the hunt for Baryonic Acoustic Oscillations or what ESA describes as “wiggle patterns” within galaxy clusters. These patterns provide a standard ruler method for measuring dark energy with the expansion rate of the universe. Euclid’s potential is overwhelming, but we’ve got a little wait on our hands before this space telescope starts beaming back any astronomical info. Euclid won’t be in the sky until 2022. It’s being assembled by Thales Alenia Space, Astrium Toulouse, and Airbus Defence and Space.

Not only is this equipment coming together for the assembly of Euclid, but researchers are already preparing for the massive onset of data that will be coming their way. Using a dark-matter particle simulation modeled with a supercomputer, researchers created the largest simulated galaxy catalogue ever made. These synthetic galaxies mimic the characteristics of real galaxies, including their shapes, colors, luminosities, spectra, and gravitational lensing distortions. This is a critical milestone in the Euclid project, and everything the researchers are preparing for will help set the foundational science for when the real data comes in. Euclid plans to station for six years and when it finally takes to the skies, we’ll all be waiting patiently for the confirmation about the parts of the dark Universe we already know, and all the parts we have yet to uncover.