ESA Euclid mission will study Dark Energy

An artist's concept of the ESA's Euclid misssion to study dark energy.

Credit: ESA/C. Carreau

Euclid is an ESA mission to map the geometry of the dark Universe.

The Euclid mission will investigate the distance-redshift relationship and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, or equivalently to a look-back time of 10 billion years.

To accomplish the Euclid mission ESA has selected Thales Alenia Space (see also the ESA press release) for the construction of the satellite and its Service Module and Airbus Defence and Space (EADS ex-Astrium) for the Payload Module.

Euclid will be equipped with a 1.2 m diameter Silicon Carbide (SiC) mirror telescope made by EADS feeding 2 instruments, VIS and NISP, built by the Euclid Consortium :

• a high quality panoramic visible imager (VIS), 
• a near infrared 3-filter (Y, J and H) photometer (NISP-P) and 
• a slitless spectrograph (NISP-S). 

With these instruments physicists will probe the expansion history of the Universe and the evolution of cosmic structures by measuring the modification of shapes of galaxies induced by gravitational lensing effects of dark matter and the 3-dimension distribution of structures from spectroscopic red­shifts of galaxies and clusters of galaxies.

The satellite will be launched by a Soyuz ST-2.1B rocket and then travel to the L2 Sun-Earth Lagrangian point for a 6 years mission.

Members of the Euclid Consortium at the Euclid Meeting in Leiden.

Credit: ESA

In this way, Euclid will cover the entire period over which dark energy played a significant role in accelerating the expansion.

NASA will also participate in the ESA's Euclid mission in conjunction with it's own WFIRST-AFTA mission, searching for Dark Energy.

Last year, NASA nominated 40 American scientists to join the 14 American scientists already part of the international Euclid Consortium, the team responsible for the science, data production and instruments for the mission. NASA will also provide 16 infrared detectors for the telescope.

Euclid's goal is to understand the nature of dark energy and its role in the expansion of the universe. To do so, it plans to use two complimentary probes to study the phenomenon. The first probe will study weak gravitational lensing, while the second will examine BAOs.

Orbiting at the second Lagrangian point, Euclid will use two instruments to study a wide region of the sky free from the contaminating light from the solar system and the galaxy. It will also observe two "Euclid Deep Fields" of the early universe.

Of the approximately 10 billion sources Euclid intends to observe, more than 1 billion will be studied for weak lensing, while tens of millions of galaxies will be measured for clustering caused by BAOs.

"WFIRST-AFTA and Euclid will make complimentary observations, with WFIRST-AFTA observing fainter galaxies and Euclid observing more sky," Nasa project manager Gehrels said.

"The combined data set will be much larger and more accurate than any other BAO measurement."

When combined with ground-based observations over a variety of wavelengths, the new observations that WFIRST-AFTA and Euclid provide, should bring significant insights into dark energy and the expansion of the universe.

"The best constraints on dark energy in the 2020s will come from a combination of Euclid, WFIRST and ground-based data," WFIRST project manager Rhodes said.

ESA: Thales Alenia Space kicks off Euclid construction

Artist’s impression of Euclid. Credit: ESA - C. Carreau

The construction of ESA's Euclid space mission to explore the 'dark Universe' will be led by Italy's Thales Alenia Space as prime contractor, beginning the full industrial phase of the project.

The announcement follows that of last month when EADS Astrium Toulouse was confirmed to build the payload module – the telescope and optical bench carrying the science instruments.

Euclid will be launched in 2020 to explore the roles played by dark energy and dark matter in the evolution of the Universe since the Big Bang and, in particular, in its present accelerating expansion.

Dark matter is invisible to normal telescopes, but acts through gravity to play a vital part in forming galaxies and slowing the expansion of the Universe.

Dark energy, on the other hand, causes a force that overcomes gravity and that is accelerating the expansion seen around us today.

Together, they are thought to comprise 95% of the total amount of mass and energy in the Universe, with 'normal' matter – from which stars, planets and we humans are made – making up the remaining small fraction. But their nature remains a profound mystery.

Alvaro Giménez Cañete

"We are pleased to confirm the prime contractor for this exciting mission. With the support of European space industry, we are a step closer to revealing the darkest secrets of the Universe," says Professor Alvaro Giménez Cañete, ESA's Director of Science and Robotic Exploration.

"This is a long-awaited milestone after the mission concept was first proposed to ESA in 2007, and we are delighted to see that the spacecraft construction can now begin," says Yannick Mellier, who leads the Euclid consortium, comprising scientists from 13 European countries and the US.

The consortium will provide Euclid's two state-of-the art scientific instruments: a visible-light camera and a near-infrared camera/spectrometer.

Together, they will map the 3D distribution of up to two billion galaxies spread over more than a third of the whole sky.

Light from the most distant galaxies streaming towards Earth is slightly bent by gravity as it interacts with matter along the way.

This is dominated by dark matter, whether associated with galaxies and galaxy clusters, or in isolation. Thus, by measuring distortions in the shapes of those background galaxies, astronomers can construct a 3D map of the dark matter in the Universe.

Furthermore, by assessing how the distribution of galaxies and galaxy clusters has changed over cosmic time, scientists can infer the role and evolution of dark energy from the dawn of the Universe until today.

The results will help to answer one of the most important questions in modern cosmology: why is the Universe expanding at an accelerating rate today, rather than slowing down due to the gravitational attraction of all the matter in it?

ESA Euclid to probe dark Universe with Astrium science module

Euclid. Credit: ESA

The module carrying the telescope and scientific instruments of ESA's Euclid 'dark Universe' mission is now being developed by Astrium in Toulouse, France.

Euclid will be launched in 2020 to explore dark energy and dark matter in order to understand the evolution of the Universe since the Big Bang and, in particular, its present accelerating expansion.

Dark matter is invisible to our normal telescopes but acts through gravity to play a vital role in forming galaxies and slowing the expansion of the Universe.

Dark energy, however, causes a force that is overcoming gravity and accelerating the expansion seen around us today.

Together, these two components are thought to comprise 95% of the mass and energy of the Universe, with 'normal' matter, from which stars, planets and we humans are made, making up the remaining small fraction. Their nature remains a profound mystery.

"Euclid will address the cosmology-themed questions of ESA's Cosmic Vision 2015–25 programme with advanced payload technologies, enabling Europe to become a world leader in this field of research," says Thomas Passvogel, Head of the Project Department in ESA's Directorate of Science and Robotic Exploration.

Astrium will deliver a fully integrated payload module incorporating a 1.2 m-diameter telescope feeding the mission's two science instruments, which are being developed by the Euclid Consortium.

The two state-of-the art, wide-field instruments – a visible-light camera and a near-infrared camera/spectrometer – will map the 3D distribution of up to two billion galaxies and the associated dark matter and dark energy, spread over more than a third of the whole sky.

By surveying galaxies stretched across ten billion light-years, the mission will plot the evolution of the very fabric of the Universe and the structures within it over three-quarters of its history.

In particular, Euclid will address one of the most important questions in modern cosmology: why is the Universe expanding at an accelerating rate today, rather than slowing down due to the gravitational attraction of all the matter in it?

The discovery of this cosmic acceleration in 1998 was rewarded with the Nobel Prize for Physics in 2011 and yet there is no accepted explanation for it.

By using Euclid to study its effects on the galaxies and clusters of galaxies across the Universe, astronomers hope to come much closer to understanding the true nature and influence of this mysterious dark energy.

"We are excited that Euclid has reached this important milestone, allowing us to progress towards launch in 2020, and bringing us ever closer to uncovering some of the Universe's darkest secrets," says Giuseppe Racca, ESA's Euclid Project Manager.

Euclid is an ESA survey mission to investigate the nature of dark matter and dark energy. It was selected as the second Medium-class mission in ESA's Cosmic Vision programme in October 2011 and formally adopted in June 2012.

The mission will be launched in 2020 and will orbit around the Sun–Earth L2 point located 1.5 million km from Earth. Science and spacecraft operations will be conducted by ESA.