Euclid space telescope to study 'dark Universe' makes progress
Europe's space mission to uncover the secrets of the "dark Universe" has reached a key milestone.
The test model of the Euclid telescope has just emerged from a chamber where it was subjected to the kind of conditions experienced in orbit.
It was a critical moment for engineers because the successful trial confirms the observatory's design is on track.
Euclid, due for launch in 2022, will map the cosmos for clues to the nature of dark matter and dark energy.
These phenomena appear to control the shape and expansion of the Universe but virtually nothing is known about them.
The €800m venture, led by the European Space Agency (Esa), will be one of a group of new experiments to come online in the next few years.
Scientists are hopeful these next-generation technologies will provide the insights that have so far eluded them.
The Structural and Thermal Model (STM) of Euclid is a near-clone of the real thing, or "flight model" (FM).
To the lay person, it's actually hard to tell the difference. But the telescope mirrors inside this copy, for example, are unpolished spares, and its "scientific instruments" don't contain the full complement of components and electronics.
An STM is, nonetheless, a very good representation.
Its job is to run ahead of the FM in the assembly process to find and fix any issues that might arise in the use of materials and the integration of equipment.
"I've seen many Structural and Thermal Models in my career and I think this is the most beautiful because it's actually nearly all made from flight hardware," Giuseppe Racca, Esa Euclid project manager, told BBC News.
One of the most important stages for the test model is when it goes in a vacuum chamber and is confronted with the challenging temperatures - both hot and cold - that occur in space.
For the Euclid STM, this thermal-vac evaluation was conducted throughout August at a factory in Cannes, France, belonging to Thales Alenia Space (TAS).
TAS leads the industrial consortium that's building Euclid.
Engineers will now shake the model and blast it with noise to gain the additional assurance that the design can withstand a rocket ride to orbit.
"We should finish the campaign by the end of October and then we will take the lessons learned and apply those to the flight model," said TAS project manager Paolo Musi.
The observatory is currently running about a year-and-a-half behind schedule. Problems have arisen in a number of areas, but Esa now believes the path ahead looks robust.
TAS will spend most of next year assembling the flight model at its factory in Turin, Italy.
Sub-contractor Airbus is putting together the module that contains the mirrors and instruments. The company should deliver this no later than the beginning of 2021.
Another full round of environmental testing follows before the completed observatory is shipped to the launch pad.
Euclid is currently booked to ride a Russian Soyuz into space in 2022, but Esa is now looking closely at the possibility of using Europe's new Ariane-62 rocket - if it's available and deemed suitable.
Once in orbit, the observatory will have two major goals.
One is to map the distribution of dark matter, the matter that cannot be detected directly but which astronomers know to be there because of its gravitational effects on the matter we can see.
Galaxies, for example, could not hold their shape were it not for the presence of some additional "scaffolding". This is presumed to be dark matter - whatever that is.
Euclid will aim to plot its distribution - and discern something of its properties - by looking for the subtle way its mass distorts the light coming from distant galaxies.
Dark energy represents an altogether different problem, and is arguably one of the major outstanding issues facing 21st-Century science.
This mysterious "force" appears to be accelerating the expansion of the Universe. Recognition of its existence and effect earned the 2011 Physics Nobel.
Euclid will investigate dark energy by mapping the three-dimensional distribution of galaxies.
There are patterns in the great voids that exist between these objects that can be used as a kind of "yardstick" to measure the expansion through time.
Euclid is just one in a series of new experiments that will tackle the dark conundrum.
Russia and Germany have just launched the Spektr-RG space telescope which will do a similar job to Euclid but by studying X-ray light in the sky (Euclid will operate in the visible and the infrared).
And then there's the Large Synoptic Survey Telescope (LSST). Its full science observations should begin in 2022 also, using a range of methods, including mapping the positions of exploding stars to measure cosmic expansion.
Isobel Hook from Lancaster University, UK, worked in one of the Nobel-winning teams and is involved in both the Euclid and LSST projects.
"We need to be able to measure the effects of dark energy at different distances and at different times in the history of the Universe. That's what could reveal something really exciting," she told BBC News.
"It's the combination of all these experiments that will give us the maximum amount of information from the one sky that we've got."
Structural and thermal model of the Euclid satellite
The structural and thermal model of the Euclid satellite recently completed its thermal qualification tests at Thales Alenia Space’s premises in Cannes, France. Integrated in near-flight configuration, including the payload and service modules, the satellite model is ready to undergo mechanical vibration tests in coming weeks.
Euclid is a medium-class mission in ESA's Cosmic Vision programme to investigate the expansion of our Universe over the past ten billion years, probing cosmic epochs from before the expansion started to accelerate, all the way to the present. To this aim, the mission will survey galaxies at a variety of distances from Earth, using a 1.2 m diameter telescope with two instruments – the visual imager (VIS) and the near-infrared spectrometer and photometer (NISP) – and covering an area of the sky equivalent to more than 35 percent of the celestial sphere.
By making use of both weak gravitational lensing, which measures the distortion of distant galaxies caused by intervening matter, and baryonic acoustic oscillations, based on measurements of the clustering of galaxies, Euclid will capture a 3D picture of the evolving distribution of both dark and ordinary (or baryonic) matter in the cosmos. This will enable scientists to reconstruct the past few billion years of the Universe's expansion history, estimating the acceleration caused by the mysterious dark energy to percent-level accuracy, and possible variations in the acceleration to 10 percent accuracy.
The satellite model shown in this photo is not the so-called flight model – the one that will be eventually launched – but it contains flight-worthy spare parts. From a mechanical point of view, it is identical to the flight model, and it allows engineers to apply extreme thermal and mechanical stresses during testing, without having to subject the delicate flight hardware to same processes. These tests, which will soon involve vibrations using a large shaker to simulate launch conditions, are performed to determine whether the thermal and mechanical properties of the actual hardware correspond to the predictions.
In order to reach Euclid’s ambitious science goals, the main design drivers include the quality and stability of the integrated optical system; the speed and completeness of its sky survey capability; accurate and stable pointing; and the ability to reliably transmit to the ground the huge volumes of scientific data that the satellite will gather. The design proposed by Thales Alenia Space, the mission’s prime contractor, is based on the experience gained with ESA’s Herschel and Planck missions, which both demonstrated excellent performance in orbit and delivered extraordinary data to delve into the mysteries of our Universe.
In addition to that, a peculiarity of Euclid is that the satellite will maintain a very stable optical performance under the most extreme attitude changes that will occur during slew manoeuvres. The recent thermal vacuum tests have simulated and successfully proven the capability to maintain the thermal stability in these conditions. The next step will be to confirm that also the optical stability will be ensured, but this will only happen during the end-to-end test of the payload module flight model next year.
Meanwhile, integration and testing of the flight model of the Euclid telescope and service module have already started at the premises of Airbus in Toulouse, France and Thales Alenia Space in Turin, Italy, respectively. The two modules will be integrated in 2021, and the complete satellite will undergo final tests in preparation to launch, which is scheduled for 2022.
Credits: ESA–S. Corvaja
ESA selects Arianespace for Euclid dark universe probe launch
Arianespace will launch ESA's Euclid mission to explore the dark universe in mid-2022 on a Ariane 62 or Soyuz rocket.
HELSINKI – Arianespace and the European Space Agency announced the signing of a contract Tuesday for launch of the Euclid dark universe exploration mission.
Euclid will be compatible with both the Ariane 62 and Soyuz launchers with a timeframe for liftoff from Kourou spaceport, French Guiana, starting in mid-2022.
The 2,160-kilogram Euclid satellite will be sent to Sun-Earth Lagrange Point 2, which is on average 1.5 million kilometers beyond Earth’s orbit.
From here Euclid will study galaxies at various distances from Earth to study the evolution of the Universe over the past 10 billion years. It will also observe the distortion of images of galaxies, an effect called gravitational lensing, in order to infer the presence of dark matter.
It will operate in visible and near infrared wavelengths and target an area covering more than 35 percent of the celestial sphere.
“Euclid will scrutinize the very nature of our Universe, shedding light on its dark side – the mysterious dark matter and dark energy,” Günther Hasinger, ESA’s Director of Science and Exploration, was quoted as saying in an Arianespace press release.
Euclid is a medium-class astronomy and astrophysics space mission selected in 2011 as part of ESA’s Cosmic Vision 2015-2025 scientific program. A consortium of nearly 1,000 scientists was formed to take responsibility for the scientific instruments and data production.
Thales Alenia Space is the prime contractor for Euclid and is also responsible for construction of its service module. Airbus Defence and Space is providing the payload module, including the telescope.
Arianespace CEO Stéphane Israël said in a press release that Arianespace is “proud to start 2020 by announcing a new iconic scientific launch for the European Space Agency”.
“With the goal of better understanding our Universe, launching this mission aboard an Ariane 62 or Soyuz is further proof of Arianespace’s ability to offer independent access to space for Europe’s ambitions,” Israël added.
Six months ago ESA picked Arianespace to launch the JUpiter ICy moon Explorer (JUICE) aboard the Ariane 64, the inaugural flight of the Ariane 6 with four P120 solid rocket boosters.
Ariane 6 is to have its inaugural mission in 2020. The 3.6-billion-euro Ariane 6 program is planned to succeed the Ariane 5 heavy-lift rocket while costing around half as much to produce.
The Ariane 6 uses two or four P120 solid rocket boosters, depending on mission requirements.
Europe’s Euclid Space Telescope Will See Cosmos with Panoramic Vision
Launching in 2022, the wide-field observatory will be one of three next-generation facilities meant to lift the veil on dark energy, dark matter and other cosmic mysteries
A lot will be riding on the European Space Agency’s (ESA’S) Euclid spacecraft when it blasts off in a rocket from the Guiana Space Center in Kourou, French Guiana, in September 2022—far more than its 1.2-meter telescope and two sophisticated wide-field-imaging instruments.
Paired with complementary measurements from two other next-generation facilities—the Vera C. Rubin Observatory and NASA’s Nancy Grace Roman Space Telescope—the data Euclid gathers during its six-year mission in a heliocentric orbit some 1.5 million kilometers from Earth will help cosmologists learn fundamental truths about the universe. Namely, the spacecraft will seek to reveal the nature of dark energy—the mysterious force powering an acceleration in the universe’s expansion—as well as of dark matter—the invisible stuff that acts as gravitational glue for galaxies and other cosmic structures. Euclid’s studies will also constitute yet another stringent test of Einstein’s general theory of relativity at vast, intergalactic scales. The discovery of breakthrough new physics—potentially even of the fate of the universe itself—could lie in store.
“Euclid’s key objectives include measurements of galaxy clustering and producing an accurate 3-D survey of the evolution of dark matter and dark energy,” says Giuseppe Racca, the spacecraft’s project manager at the ESA. “This will help researchers to determine the rate of the accelerated expansion of the universe and find out if dark energy has a constant value or not.”
Euclid, which is currently in the final stages of integration at the Airbus facility in Toulouse, France, will measure the shapes of more than two billion galaxies and the distances of hundreds of millions of others with unprecedented fidelity via observations in both visible and near-infrared wavelengths. “In terms of quality, the images will be superior to anything else taken until now,” Racca says.
Euclid’s visible-wavelength instrument will also measure the visual distortion of distant galaxies produced by a phenomenon known as weak gravitational lensing. Somewhat akin to the way objects can appear magnified, shrunken or stretched when seen through glass or water, our views of galaxies can be distorted when their light passes through regions of warped spacetime surrounding stars, galaxies, black holes and clumps of dark matter on its way to Earth. By analyzing this distortion, researchers can calculate the mass of the intervening matter, visible or dark, responsible for the light deflection while also constraining the influence of dark energy.
“The theory of general relativity says something about how the universe should be expanding, depending on what’s in it. And it says something about how light rays should be gravitationally lensed by matter distribution,” says Rachel Mandelbaum, a physicist at Carnegie Mellon University. “Using the measurements from Euclid and other future missions, we can construct tests to see if the data obtained from the weak-lensing observations is consistent with general relativity.”
Probing general relativity is also one of the objectives of the Roman Space Telescope. Scheduled to launch in late 2025, the telescope’s wide-field instrument will gather light from a billion galaxies, gauge distances to supernovae, and more. (Most notably, Roman will also test new technologies for imaging planets around nearby stars.) Its measurements of galaxies and supernovae will allow researchers to better estimate the expansion rate of the universe, clarifying the role of dark energy and, with that information, further testing the validity of general relativity.
Similar to Euclid, Roman will also produce a three-dimensional map of the distribution of galaxies. But it will operate in just the infrared region. At 2.4 meters in diameter, its mirror is twice the size of Euclid’s, allowing Roman to peer deeper into the sky—and thus cosmic history—than its European counterpart.
These common science objectives and the likely temporal overlap in their operations makes NASA’s next-generation telescope complementary to the Euclid mission. “If Euclid sees something interesting, the Roman Space Telescope has the flexibility to optimize and modify its scientific program so that it’s maximally sensitive to that region,” says David Spergel, co-chair of Roman’s science team and director of the Center for Computational Astrophysics at the Flatiron Institute in New York City.
Another key player in the investigation of dark matter and dark energy is the Rubin Observatory, which will conduct the decade-long Legacy Survey of Space and Time (LSST) once it begins full operations on a remote peak in the Chilean Andes in late 2022. Information from the observatory could prove crucial for aiding the studies of its space-based counterparts.
“The Euclid observations are going to be supplemented with data from ground-based telescopes,” says Mandelbaum, who is also spokesperson for the Rubin Observatory’s Dark Energy Science Collaboration. “For example, the Rubin Observatory will be able to provide color measurements of galaxies in order to understand how far away they are.”
According to Mandelbaum, the two facilities’ complementary feature also extends to their design. “While Euclid is mostly going to look somewhere in the sky, take observations and then look somewhere else, [Rubin’s] telescope comes back to the same place in the sky after every few nights to monitor time-variant effects during its LSST survey,” she says.
Pooling and comparing the observations made by all three telescopes could prove extremely useful. “A powerful combination will be Rubin's first year of data with the Euclid data covering the same region of the sky,” Spergel says. “Similarly, in 10 years’ time, the combination of Rubin’s decade-long optical data set and Roman’s infrared measurements will be particularly powerful.”
The collective measurements over the next 10 years could also help solve one of the mysteries of physics. Analyzing the data on how galaxies and even larger cosmic structures grow may allow researchers to place stricter constraints on the masses of neutrinos, fundamental particles that possess no electrical charge and scarcely interact with ordinary matter. Trillions of these ghostly particles pass through your body each second with barely any effect whatsoever. But on intergalactic scales, their vast numbers can have important influences on the past and future evolution of cosmic structure.