They are the great, influential unknowns in space: dark matter and dark energy. The European space probe "Euclid" is now intended to take research into these two phenomena - about which almost nothing is known so far - take a big step forward.
The aircraft of the European Space Agency ESA took off on Saturday from the US spaceport Cape Canaveral on board a Falcon 9 rocket from the US company SpaceX. Less than an hour later, the probe sent a first signal from space. "Euclid is on his way to unveil the cosmic mystery of dark matter and dark energy," ESA wrote on Twitter. "The atmosphere is very, very good here," said ESA Director General Josef Aschbacher.
"Euclid" is supposed to bring light into the darkness
"Euclid" is a quantum leap in mankind's ability to study the origin and development of the universe, said Joseph Mohr from the Ludwig Maximilian University (LMU) in Munich after the launch of the probe, according to a statement.
Together, dark matter and dark energy form an extremely large part of the universe. All other known components - stars, planets, our Milky Way, other galaxies - make up only about five percent, as Giuseppe Racca, the ESA program manager for "Euclid", explained in the run-up to the launch. "Cosmology is in what could be called an embarrassment."
Dark matter and dark energy are determining factors in space. In the universe, astrophysicist David Elbaz explained, there is more gravity than would be assumed based on the visible parts. "The Sun is spinning around the center of the Milky Way at such a high speed that it should erupt from the galaxy. And if it doesn't erupt, that means it's being attracted to another mass that we don't see." That is the dark matter. Dark energy, on the other hand, describes a kind of anti-gravity that makes galaxies seem to repel each other. Both are extremely difficult to research.
A look into the past of the universe
"Euclid" should now bring some light into the darkness. "Making the invisible visible," is how astrophysicist Elbaz sums up the core of the mission. At the heart of the probe, which is around 4.7 meters long, 3.5 meters wide and weighs just under two tons, is a high-resolution telescope. This is equipped with two cameras - one for the visible wavelength range and one for the near-infrared range.
With the telescope, Esa wants to take a look at the past of the universe and explore its development over the last ten billion years. Also, aim to create a 3D map where time is the third dimension. In total, data on billions of galaxies is to be collected.
A 1.4 billion euro mission
Researchers hope that the mission will show how the universe has expanded and how individual structures came into being. From this they want to draw conclusions about dark matter and dark energy and also understand how dark matter and gravity are related. Jochen Weller from the Max Planck Institute for Extraterrestrial Physics was enthusiastic: "Euclid will allow us to test Einstein's theory of gravity at large distances and - who knows? - maybe we will have to extend his theory."
First of all, the approximately 1.4 billion euro mission, in which more than 20 countries are involved, is scheduled for six years. "Euclid" is to fly about 1.5 million kilometers into space. It should take about a month for the probe to get there. Some tests follow, the telescope is checked and the instruments are switched on. After a two-month test phase, during which only routine observations are made, the mission is scheduled to start its actual work in autumn and deliver the first images.
The information collected by "Euclid" could be a great asset for research. Racca, the program manager for "Euclid", expects more data on extragalactic astronomy in the first year of the mission than has previously been available from any other comparable mission. "I expect that 'Euclid' will flood the scientific community with an unprecedented, massive amount of data." Ralf Bender from the Max Planck Institute said that Europe could thus take a leading position in the research of dark matter and dark energy.
Astrophysicist Elbaz assumes that about a year and a half after the start of "Euclid" we could have a better understanding of dark matter for the first time. But what the mission will bring in the long term for findings is not foreseeable. "To know today what will be the impact of our better understanding of physics and of what 'Euclid' will tell us (...) is impossible."