A NEW SPACE probe that will launch early on Saturday has the potential to provide answers to some of the biggest mysteries in the cosmos. If everything goes according to plan, the Euclid telescope will survey countless galaxies while scouring the last 10 billion years of cosmic history. It will provide astronomers with the information they need to comprehend two enduring mysteries: dark matter and dark energy.
Euclid is a space telescope, but it is also more. At a press conference last week, René Laureijs, the mission's project scientist, declared that the device was actually a dark energy detector.
The European Space Agency, or ESA, is aiming to launch from Cape Canaveral, Florida, on July 1 at 11:11 Eastern time after more than ten years of arduous work. The trip to space will be provided by a SpaceX Falcon 9 rocket. (The agency is reserving Sunday as a backup launch date and will stream the event live here.)
Nearly all of the sky that can be recorded without aiming the telescope across the Milky Way disk will be covered by Euclid's survey of more than one-third of the sky. Such coverage will enable researchers to examine in great detail how the universe's expansion has quickened, most likely due to dark energy, an unobservable phenomena.
Astrophysicists only fully comprehend around 5% of the cosmos, the atoms that comprise everything from toasters to toasters to stars and planets. However, research using Planck, another ESA satellite telescope, suggests that dark matter, the invisible framework of the cosmos that controls where and how galaxies form, makes up approximately 25% of the universe. The rest is made up entirely of dark energy, a nebulous and speculative repulsion that controls the universe's evolution by tearing it apart. Dark energy took over as the universe's primary force a few billion years ago, ensuring not only that it would continue to grow but also that its rate of expansion would quicken.
The ratio of the dark energy pressure to its density, or w, is an important parameter that Laureijs and his associates seek to examine. Einstein proposed a "cosmological constant," or the idea that even though the universe is made up primarily of empty space, it has its own energy and interacts with gravity. According to this idea, the dark energy pressure should be equal to the energy density minus one. In other words, w should equal -1 if dark energy is the cosmological constant.
That seems to be the case so far, although investigations using older telescopes have significant measurement uncertainties. By making more precise measurements for w and seeing if it turns out to be anything other than -1, data from Euclid will reveal whether or not a cosmological constant is the proper explanation for the universe's acceleration. It will also demonstrate whether w has altered over the course of cosmic history.
According to Carole Mundell, the ESA's head of science, "we're looking at some of the most fundamental questions of cosmology." This mission will allow us to map out the cosmic structure and the history of the universe's expansion with remarkable precision.
Euclid will launch into space and go to Lagrange point 2, 1.5 million kilometers from Earth, where it will have a clear perspective of the universe, be able to communicate with scientists, and get continuous sunshine for its solar panels. The telescope has two instruments that can be used at once: a visible-wavelength camera with 36 sensitive detectors, known as charge coupled devices, for measuring the shapes of billions of galaxies, and a near-infrared spectrometer and photometer with 16 detectors that will offer the widest infrared field of view of any space telescope. Later this year, following a few months of testing and instrument calibration, Euclid will start its science mission.
It will be located next to NASA's James Webb Space Telescope in L2 orbit, but "it's kind of an anti-JWST. The entire purpose of Euclid is to broaden out and look over a big portion of the sky rather than focusing on a very limited area of it, according to Mark McCaughrean, senior adviser for science and exploration at ESA. Euclid won't be able to zoom in on particular objects like the JWST and Hubble do; instead, it will provide a wide-angle picture. "This mission is in statistics. The goal is to overwhelm oneself with data and galaxies so that you can begin to discern the subtle signals, according to McCaughrean.
The Euclid team's astronomers intend to perform two crucial observations that strongly rely on statistics. The first will include measuring weak gravitational lensing, which is when light from farther away galaxies are gently bent by the gravity of huge objects, primarily dark matter, altering the pictures of those galaxies. Only catalogs jam-packed with galaxies can be used to study it.
The same holds true when looking at baryon acoustic oscillations. Sound waves rolled over ordinary matter, a mixture of particles and radiation, in the early universe. As a result, galaxies developed with a quantifiable pattern in their density distribution. Scientists from Euclid will be able to comprehend the nature of dark energy and the expansion of the universe by examining the patterns that these oscillations leave behind at various points in cosmic time.
Euclid's equipment will gather vast amounts of data with image quality comparable to Hubble's but covering 15,000 square degrees of the sky in order to make progress on such statistics. According to Luca Valenziano, a cosmologist at Italy's National Institute for Astrophysics and member of the Euclid project, that would take millennia to complete using Hubble. "This is an incredible potential, and only Euclid can do that because it can explore the infrared sky, which is not accessible from the ground," he claims.
One significant way that Euclid will be distinct from ground-based surveying telescopes like the Dark Energy Survey, the Dark Energy Spectroscopic Instrument, and the planned Vera Rubin Observatory is through the utilization of infrared. Most infrared wavelengths are blocked by the atmosphere, making it impossible for telescopes on Earth to observe them. However, if they are maintained cold enough, space telescopes like JWST and Euclid can. Heat radiation is essentially what infrared light is. When analyzing galaxies, Euclid uses infrared instruments that allow him to see through dust clouds and conduct a more thorough investigation into the early cosmos.
The biggest question regarding the universe's expansion has recently been investigated by physicists like Mat Madhavacheril using the Atacama Cosmology Telescope: Why the measured expansion rate appears to be slightly different when using probes of the distant universe in comparison to when using nearby objects, like supernova explosions. He claims that Euclid, which will be their most potent instrument yet and be able to methodically map a large portion of the universe, may assist to finally answer the mystery. "Euclid offers a lot of benefits. We're enthusiastic about it, and when the Euclid data become available, we'll seize the opportunity," he says.