The Euclid infrared telescope system has successfully launched into space, holding the hope of unraveling the mysteries of astrophysics. A new space exploration device has taken off, carrying the potential to address the most significant astronomical enigmas.
If all goes as planned, in the next six years, the Euclid Space Telescope will scan billions of galaxies meticulously, delving into what the last ten billion years of the universe might conceal. The data collected will underpin the process of deciphering two major mysteries, namely dark matter and dark energy.
“Euclid is not just an ordinary telescope. It’s a dark energy hunter,” said René Laureijs, a prominent scientist involved in the project, during a conversation with the media.
After more than a decade of effort, the European Space Agency (ESA) successfully constructed Euclid and launched it into space on July 1st. Carried into space atop SpaceX’s Falcon 9 rocket, Euclid embarked on its solitary journey into the frigid space, slowly moving towards its destination.
The Euclid space telescope.
Euclid will survey a vast expanse of space, enabling scientists to precisely calculate the rate of cosmic expansion. In theory, scientists believe that the universe’s expansion is driven by the effects of dark energy.
In reality, astronomers have only understood about 5% of the universe – these are the particles that make up ordinary matter, from stars to planets, from lowly organisms to high-ranking species. According to a study conducted by the ESA’s Planck satellite, roughly 25% of the universe is composed of dark matter, an intricate “scaffold” that determines the location and manner in which galaxies form.
The remainder of the universe is dark energy, a newly discovered force that exists only in theory, causing the universe to expand in all directions. Billions of years ago, dark energy was the dominant component of the universe, not only causing it to expand but also accelerating that expansion.
One of the significant parameters of interest to Mr. Laureijs and his colleagues is “w,” the ratio of the pressure of dark energy to the density of the universe. Einstein proposed a theory of a “cosmological constant,” or in other words, the notion that most of the universe is like a vast void, containing its own energy components and bound by gravity.
If this theory holds true, then the pressure of dark energy will be equal to the negative part of the energy density. In simpler terms, if dark energy is the primary mysterious cosmic constant, then w = -1.
The universe continues to expand in all directions at an increasing rate.
Once it reaches outer space, Euclid will travel to the second Lagrange point (L2), approximately 1.5 million kilometers from Earth. Here, the telescope will have a clear view of the distant universe while still maintaining easy communication with its home and enjoying abundant solar energy. The telescope has two parallel systems on board: a visible-wavelength camera with 36 sensors to measure the shapes of billions of galaxies, alongside a pair of near-infrared spectrometers with 16 sensors for capturing the infrared.
Following its arrival at L2 and fine-tuning over the course of several months, Euclid will become fully operational in the fourth quarter of this year.
Lagrange point 2 may sound familiar to astronomy enthusiasts. Indeed, Euclid will be positioned close to NASA’s James Webb Space Telescope (JWST), but the two instruments serve entirely different functions. Instead of focusing on a single celestial object like the JWST, Euclid will observe a vast expanse of the cosmos. Mark McCaughrean, a senior science adviser for ESA, notes that “This is a statistical mission. The goal is to gather flood data on galaxies and then pick out small signals.”
A group of astronomers working on the Euclid project is planning to undertake two crucial measurement tasks, both closely related to statistics. The first task will involve measuring the weak gravitational lensing effect, occurring when the massive objects – mostly dark matter – bend the light shining towards them. The light received may include numerous galaxies hidden behind these massive objects.
The other task involves studying baryon acoustic oscillations. In the early universe, acoustic waves moved through the combination of normal matter and radiation, generating a measurable pattern of galaxy density when they formed. By researching the patterns generated by baryon oscillations, scientists can gain a better understanding of the universe’s expansion and the nature of dark energy.
The Euclid telescope during assembly.
To lead such a large-scale statistical project, the instruments on the Euclid telescope will collect an immense amount of data from a vast portion of the sky, spanning up to 15,000 square degrees. According to Luca Valenziano, an astrophysicist at the Institute of Astrophysics in Italy and a member of the Euclid team, the Hubble telescope would take centuries to collect such data. “This is a tremendous potential, only Euclid can do it when it surveys the infrared sky, which cannot be observed from the ground,” he said.
Thanks to infrared technology, Euclid differs from other ground-based systems. Equipment on Earth cannot observe most infrared wavelengths due to atmospheric interference. However, when in space, instruments like JWST and Euclid can achieve the impossible. The infrared instruments on Euclid can help it see dust clouds and even look into the universe’s past.
In recent years, astronomers have been diligently searching for reasons behind the universe’s expansion discrepancies – the differences between vast measurements needed for meaningful data. Euclid could help scientists resolve this conundrum, being a robust system capable of observing an extensive cosmic realm.
With the rapid advancements in technology, humanity is gradually unlocking the most challenging questions in the history of science.