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

Euclid and the Geometry of the Dark Universe

Article written: 21 Jun , 2012
Updated: 23 Dec , 2015

Euclid, an exciting new mission to map the geometry, distribution and evolution of dark energy and dark matter has just been formally adopted by ESA as part of their Cosmic Vision 2015-2025 progamme. Named after Euclid of Alexandria, the “Father of Geometry”, it will accurately measure the accelerated expansion of the Universe, bringing together one of the largest collaborations of astronomers, engineers and scientists in an attempt to answer one of the most important questions in cosmology: why is the expansion of the Universe accelerating, instead of slowing down due to the gravitational attraction of all the matter it contains?

In 2007 the Hubble Space Telescope produced a 3D map of dark matter that covered just over 2 square degrees of sky, while in March this year the Baryon Oscillation Spectroscopic Survey (BOSS) measured the precise distance to just over a quarter of a million galaxies. Working in the visible and near-infrared wavelengths, Euclid will precisely measure around two billion galaxies and galaxy clusters in 3 dimensions in a wide extragalactic survey covering 15,000 square degrees (over a third of the sky) plus a deep survey out to redshifts of ~2, covering an area of 40 square degrees, the 3-D galaxy maps produced will trace dark energy’s influence over 10 billion years of cosmic history, covering the period when dark energy accelerated the expansion of the Universe.

The mission was selected last October but now that it has been formally adopted by ESA, invitations to tender will be released, with Astrium and Thales Alenia Space, Europe’s two main space companies expected to bid. Hoping to launch in 2020, Euclid will involve contributions from 11 European space agencies as well as NASA while nearly 1,000 scientists from 100 institutes form the Euclid Consortium building the instruments and participating in the scientific harvest of the mission. It is expected to cost around 800m euros ($1,000m £640m) to build, equip, launch and operate over its nominal 6 year mission lifetime, where it will orbit the second Sun-Earth Lagrange point (L2 in the image below) It will have a mass of around 2100 kg, and measure about 4.5 metres tall by 3.1 metres. It will carry a 1.2 m Korsch telescope, a near infrared camera/spectrometer and one of the largest optical digital cameras ever flown in space.

Sun Earth Lagrange Points Credit: Xander89 via Wikimedia Commons

Dark matter represents 20% of the universe and dark energy 76%. Euclid will use two techniques to map the dark matter and measure dark energy. Weak gravitational lensing measures the distortions of light from distant galaxies due to the mass of dark matter, this requires extremely high image quality to suppress or calibrate-out image distortions in order to measure the true distortions by gravity. Euclid’s camera will produce images 100 times larger than those produced by Hubble, minimizing the need to stitch images together. Baryonic acoustic oscillations, wiggle patterns, imprinted in the clustering of galaxies, will provide a standard ruler to measure dark energy and the expansion in the Universe. This involves the determination of the redshifts of galaxies to better than 0.1%. It is also hoped that later in the mission, supernovas may be used as markers to measure the expansion rate of the Universe.

Find out more about Euclid and other Cosmic Vision missions at ESA Science

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

Second image caption: Sun Earth Lagrange Points Credit: Xander89 via Wikimedia Commons

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18 Responses

  1. donjasjit says

    Where does ESA find the money for all those new missions when Greece, Spain and Italy are on the verge of financial meltdoen.

    • SJStar says

      Achtung. It is mostly the Germans financing these missions – among others.

    • I live in Greece, and these are my thoughts exactly! I’m a Big space advocate, and I’d like to see this project launch ASAP, yet this question remains. When everyone in nothern Europe and particularly in Germany (one of the biggest contributors to ESA) are screaming about the burden of the bailout packages to their economies, and these countries are now in danger of losing their AAA financial rating, how can they afford financing everything? I really hate conspiracy theories, but some times things doesn’t add up…

      • Lord Haw-Haw. says

        The funding for the Euclid mission is explained somewhat better here:

        Greece is not mentioned per se as a financial contributor, however it is feasible it is a participant via the European Consortium (EC) which has 100 scientific laboratories across Europe contributing to the mission.

      • Odd. Making a case for more social handouts instead of scientific progress.

      • lcrowell says

        What is not often talked about is the role of banks in all of this as the primary driver. I strongly suspect there is a world wide rumble of banks to determine which of them will have a controlling share in what might be emerging as a financial oligarchy that controls the world economy. Bond ratings are interesting, for the following seems to play itself out. Bank A wants to diminish the holdings of bank B, or demolish it altogether. Bank B hold bonds of some nation, call it Forgotonia. Now assume that Forgotonia has some structural vulnerabilities. Bank A may either dump its holding of Forgotonia bonds or leverage its power to down grade the bond rating of Forgotonia. This puts downward pressure on bank B, and this may throw Forgotonia into the economic tank.

        Greece had such vulnerabilities, though they were not caused by liberal policies. In fact the right wing held office for much of the preceding 10 years. The preceding administration was similar to what has been seen with the American Republicans; they talk big about financial and fiscal responsibility, but in reality they run up debt enormously. There are also problems with the inability to enforce revenues. The barracuda banks came in and had a feast at the expense of both Greece and a number of banks holding Greek bonds.

        The Merkel administration is pushing austerity, which is guaranteed to depress thing further, at least for a while. However, I think with this you could consider looking at who might be really pulling the strings. Is it Deutschland or is it really Deutsche Bank?

      • DrFlimmer says

        I have much to say about this, but I don’t want to start a flame war here (in this topic you have certainly as many opinions as participants), so only one thing:

        As much as I agree with you, I want to stress that Merkel’s austerity is certainly the way to go in the long run. It’s too bad that “long runs” are mostly not the option any more. Most politicians, bankers, and managers do not think longer than 3 month ahead.

      • Member
        IVAN3MAN_AT_LARGE says

        Murky Merkel strikes again!

      • lcrowell says

        It must be remembered that things like economies are complete artifacts. Money itself is utterly artificial and is really created out of thin air. It only has value because people believe it does. It is all rather related to religion, and it is what we have organized our world and lives around.

        There are two things that may have to be navigated against. One is to start creating more stimulus money than what can be realistically accounted for. The opposite is to hold tight to monetary policies to the point that you end up with serious levels of grief or to where dead bodies start stacking up around you.

        Money is created out of thin air by national banks to generate credit. It is not as if the money is taken from some vault. This can also mean creating money at the federal or treasury level. What is done is that by creating debts the debtor pays off the loans and in turn creates more in the way of business or wealth than the original seed money. This is the logic of stimulus packages. With the American market crash of 1929 the policies were to restrict credit. The effect was to implode the economy further into the depression. In 2008 the opposite was done, which prevented a complete depression. In fact GW Bush was the first to start this. The money is created out of thin air; after all money is something we define. The one problem is that the returns on debt have consistently narrowed in recent times. Further, if you create loads of credit or stimulus money you can create a crisis of confidence in money, which can lead to inflationary spirals.

        If you tighten up credit severely, you can end up with a deflationary situation. In that setting money starts to increase in value, which happens if there is less and less of it around. In that setting (which impacted the US in the 1930s) there is no incentive to invest money at all; it is better to just let it sit somewhere and increase in value on its own. This is all mass-psychology, but it has severe impacts on people’s lives. This is made complicated in the EuroUnion, for there are relative asymmetries between different national economies.

        So somewhere I think lies a middle path. Though I must confess I have some pretty grim prognostication for the entire world economy. I have rather grim suspicions that some sort of world collapse is coming, and the world is going to enter into another phase of mass-insanity. This happens about every 80 to 100 years, and we are about due for the next tango.


      • Member
        IVAN3MAN_AT_LARGE says

        Have you ever thought of running for president, Mr. Crowell?

      • lcrowell says


        Seriously the political structure of this nation, and I dare say largely of all Republics, parliamentary or representative systems in the world, have been reduced to a sort of theater. The political parties are really vassal estates to the corporate and financial powers which really run things. In the case of this country big money supports the Republicans most often which things are running well, and will support the Democrats or so called liberals when the system is in trouble. Obama got twice the campaign money that McCain got, largely because the Dems are more likely to throw the Keynesian levers and switches to adjust the economy to cover the butts of those who created the problem.

        Every President who is elected soon after inauguration has various meetings with corporate leaders who tell that President how ball is going to be played. It might be said that the velocity with which a Republican President’s knees hits the floor is a bit higher than the Democrat. If a President does not play ball properly, those with the money will demolish his chances with the next election.

        The liberals are every much the corporate party as the conservatives, it is just that the liberals think the left overs from the corporate banquet should be boxed up for some public use. The conservatives think not. Also if you ask me the Republicans have of late been raising up people who are either borderline personality disordered or who are simply sociopaths. Yet I have no illusions that somehow if the liberals really win the day that the economic clouds will part and the sunshine of prosperity shines forth. I use liberal vs conservatives, for this really plays out in every country, particularly the OECD nations in N. America, W. Europe, Japan and the other rising Asian countries that are ostensibly democracies. Clear evidence of that was the T. Blair “Labor” government, and now look at the Cameron Drowning Street (drowning used intentionally) administration. It is all largely a farce.

      • Member
        IVAN3MAN_AT_LARGE says

        Thank you for taking the time to reply, Mr. Crowell. Your political insights are always a pleasure to read!

      • DrFlimmer says


    • maybe they realize that spending money on cutting edge research in technology and science is actually an investment that has
      been shown to pay for itself over and over again, rather than clinging
      to the old conservative cliche that sending money into space is a waste.

    • Olaf2 says

      It creates jobs. Someone has to build these things. And someone has to clean the toilets and deliver the pizza’s.

      And as addition, you get new technology that can be used to help people. GPS is one such example, weather satellites another.

    • Martin_Silenus says

      Some thoughts :
      – Although the Euclid project has only now been announced to go into development phase, there has already much work been done on its study phase. The cosmic vision program and its budget was approved already a long time ago.
      – Total cost is estimated around 800 meuro. However, this has to be spread out over its total developing time, let’s say around 10 years. This is thus only 80 meuro per year.
      – What’s 800 meuro when the crisis is about 100 billion euro?
      – In fact, there’s a ministerial conference later this year, deciding over the new budgets for ESA. Everybody is looking anxiously to the outcome of this conference, nobody seems to know what to expect in these times of crisis and austerity.

  2. lcrowell says

    This is almost a type of cosmic geodetic map. This will likely prove to be very valuable in benchmarking ?CDM models.

  3. Torbjörn Larsson says

    Getting back from the dark economy of the Eclectic Overlords, whoever they may be…

    This is really interesting! Planck looks at CMB, and will improve standard cosmology from that end. Euclid will dig into the remainders. Maybe it will be “the exquisite standard cosmology” soon.

    And then off topic straight away: the L2s are getting crowded!

    The Sun-Earth L2 is the favorite waystation of deep space observatories.

    And the Earth-Moon L2 is a favorite for deep space exploration (if NASA’s ISS spin off Exploration Gateway will become reality), and for asteroid mining (to keep tugged asteroids safely away from Earth).

    Who own those pieces of property anyway? The future rent must be off this Earth,,,

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