'Euclid' will scan the cosmos to study dark matter
July 01, 2023, | SpaceX successfully launched the Falcon 9 v1.2 FT Block 5 rocket n° B1080.2 with the European Space Agency satellite, Euclid, into a Sun-Earth Lagrangian transfer orbit L2, also known as Sun-Earth Lagrange point 2. The 568-tonne rocket took off from Space Launch Complex 40 (SLC-40) at Cape Canaveral Space Force Station in Florida at 11:12 am ET (15:12 UTC). The 'core' of the B1080 first stage previously launched the Ax-2 manned mission to the International Space Station. After separation, the first stage successfully landed on the droneship "MARMAC 302" aka A Shortfall of Gravitas, stationed in the Atlantic Ocean 683km away from Cape. The head fairing shells will be recovered at sea by the support vessel Doug.
The Euclid Spacecraft deployed into the L2 transfer orbit, which will take nearly a month to reach the predetermined orbit
Thales Alenia Space was selected in June 2013 to build the spacecraft. EADS Astrium was selected to build the research module, including the telescope. The propulsion system was built by OHB of Sweden. The 2,100 kg spacecraft is about 4.5 meters high and 3.1 meters wide (with the appendages extended). The nominal duration of the mission will be six years. Euclid will map the geometry of the dark Universe and investigate the distance-redshift relationship and the evolution of cosmic structures by measuring galaxies and galaxy clusters down to deviations of about 2, or the equivalent of a backward time of 10 billion years. It will therefore cover the entire period during which dark energy played a significant role in accelerating the expansion.
The total cost of the device is around 600 million USD. Two cameras will be installed on board, one of which will make observations in the infrared range and the other in the optical range. Both cameras are linked to the 1.2-meter telescope. The spacecraft will use two techniques to study the dark universe, both involving precise measurements of galaxies billions of light-years away. The observations will offer the best measurements of how the universe's acceleration has changed over time, offering new clues about the evolution and fate of the cosmos. both involving precise measurements of galaxies billions of light years away. The observations will offer the best measurements of how the universe's acceleration has changed over time, offering new clues about the evolution and fate of the cosmos. both involving precise measurements of galaxies billions of light years away. The observations will offer the best measurements of how the universe's acceleration has changed over time, offering new clues about the evolution and fate of the cosmos.
A large-amplitude halo orbit (~1 × 106 km) around the second Lagrange point of the Sun-Earth system (L2) was selected because it offers ideal operating conditions: a benign radiation environment, necessary for the sensitive detectors and conditions very stable observation sites far enough away from the disturbing Earth-Moon system. The Lagrange point is a place where the gravitational attraction of two large masses, the Sun and the Earth in this case, is precisely equal to the force required for a small object, such as a spacecraft, to maintain a relatively stationary position behind the Earth, as seen from the sun. Furthermore, the amount of propellant needed is very favorable compared to alternative orbits.
The Euclid mission is Selected in October 2011 alongside Solar Orbiter as one of the first two medium-class missions in the Cosmic Vision 2015–25 plan, Euclid has received final approval from ESA's Science Program Committee to move into the full construction phase, leading to for its launch in 2020. The committee also formalized an agreement between the ESA and funding agencies in several of its Member States to develop the two scientific instruments, a visible wavelength camera, and a near-infrared camera/spectrometer, and the large distributed processing system needed to analyze the data they produce. The satellite is equipped with the most complex parallel computing system, which will process data from the cameras.
Studying redshift and dark matter and energy
The 'Mission Euclid' (“Euclid”, named after the Greek sage of Alexandria) is a spacecraft designed exclusively for the study of dark energy and dark matter. The spacecraft will use its instruments to analyze the motion of more than a billion galaxies. In the 1970s, astrophysicists discovered that the stars around many spiral galaxies were rotating very fast. To explain this discrepancy between the theoretical model and the observational data, the concept of hidden mass (not accessible to observation) was introduced. As it turned out, there is a lot of this mass - much more than visible. In turn, in the 90s of the last century, while studying class Ia supernovae, astrophysicists discovered that the Universe is expanding with acceleration. To explain this accelerated expansion, it took the concept of dark energy, which separates space. According to modern concepts, ordinary matter makes up 4% of all matter-energy in the Universe (the equivalence of matter and energy is determined by the well-known Einstein equation E=mc2), dark matter – 24%, and the remaining 72 is made of dark energy.
The ESA report says that more than a thousand scientists from more than a hundred scientific institutes will participate in the creation of devices. The British Space Agency, created only in 2010, participated in the creation of the device. NASA also got into the project – in particular, providing infrared detectors. Before it was about NASA being the main driving force of the project, but over time, the European Space Agency supplanted the American one.
"NASA is very proud to contribute to ESA's mission to understand one of the greatest scientific mysteries of our time," said John Grunsfeld, associate administrator of the Science Mission Directorate at the agency's headquarters in Washington. NASA contributed 16 state-of-the-art infrared detectors and four spare detectors to one of the two science instruments. "The Euclid mission is designed to investigate one of the most fundamental questions in modern cosmology, and we welcome NASA's contribution to this important endeavor, the latest in a long history of cooperation in space science between our two agencies," said Alvaro Giménez, Director of Research and Robotic Exploration at ESA. NASA's Euclid Project Office is based at NASA's Jet Propulsion Laboratory in Pasadena, California. JPL contributed the infrared flight detectors to the scientific instrument. NASA's Goddard Space Flight Center in Greenbelt, Maryland tested these detectors prior to delivery. Three US science teams will contribute to scientific planning and data analysis. JPL is managed for NASA by the California Institute of Technology in Pasadena.
In addition, the American agency appointed three scientific teams, totaling 40 new members for the Euclid Consortium. This was in addition to the 14 American scientists already supporting the mission. The Euclid Consortium is a 1,000-member international body that has overseen the development of the instruments, will manage science operations, and will analyze the data.